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Louro, Patrícia Isabel Ramos. "Avaliação e caracterização da ação inibitória de iminociclitóis na atividade alfa-glucosidase de células de mamífero." Master's thesis, Universidade de Évora, 2014. http://hdl.handle.net/10174/10890.
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Os inibidores das α-glucosidases, entre os quais se enquadram os iminociclitóis, são agentes de elevado interesse terapêutico uma vez que podem contribuir para a diminuição da absorção intestinal de glucose e, consequentemente, para um desagravamento da hiperglicemia em condições patológicas como a diabetes.
Neste trabalho procurou-se estudar a ação de alguns compostos novos da família iminociclitol na atividade α-glucosidase de enterócitos de mamífero.
Dos quatro compostos estudados (S,S) e (R,R) (3,4)-1-benzilpirrolidina-3,4-diol e (3R,4R)-pirrolidina-3,4-diol provocaram uma diminuição significativa da atividade enzimática α-glucosidase, sendo os IC50 inferiores a 5,8 mM. Os resultados apontam ainda para um mecanismo de inibição do tipo misto com valores e KI inferior a 1,2 mM. Os compostos estudados revelaram ser pouco tóxicos.
Os resultados sugerem que estes compostos não constituem fármacos promissores enquanto inibidores de α-glucosidases, de mamífero. Contudo, dada a sua baixa toxicidade não são de excluir outras aplicações nomeadamente, agroindustriais; ### Abstract:
“Evaluation and characterization of inhibitory action of iminociclitols on alpha-glucosidase activity in mammal’s cells.”
Iminocyclitols as α-glucosidases inhibitors, are agents with high therapeutical interest since they contribute to diminish intestinal glucose absorption and consequently, to ameliorate hyperglycimia in pathological conditions such as diabetes.
The aim of this work was to study the inhibitory effect of several iminocyclitol compounds on the α-glucosidase activity from enterocytes.
Among the compounds studied, three, (S,S) and (R,R) (3,4)-1-benzilpyrrolidine-3,4-diol and (3R,4R)-pyrrolidine-3,4-diol had significant inhibitory action over α-glucosidase enzymatic activity with IC50 under 5,8 mM. It also show that the KI under 1,2 mM. Moreover, the compounds presented negligible toxicity effects.
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Bothon, Fifa. "Phytochimie et propriétés biologiques d'extraits de plantes antidiabétiques utilisées au Bénin." Thesis, Clermont-Ferrand 1, 2012. http://www.theses.fr/2012CLF1PP05.
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Le présent travail rend compte des études phytochimiques et biologiques d'extraits non volatils de quatre plantes utilisées au Bénin dans le traitement du diabète. La première partie passe en revue la bibliographie sur les plantes sujettes à notre étude. Dans cette partie, la systématique, l'importance en pharmacopée ainsi que les travaux déjà effectués sur ces plantes ont été présentés. La deuxième partie présente le mode d'extraction et les études chimiques des extraits et les résultats obtenus. La spectrophotométrie a permis de déterminer quelques grandes familles de composés présents dans les extraits : les polyphénols totaux, les flavonoïdes et les tanins tandis que la GC/MS et la LC/MS ont servi à mettre en exergue la présence de composés volatils et non volatils. La troisième partie décrit les tests biologiques in vitro et ex vitro effectués sur les extraits. Les extraits ont montré de manière générale des activités : inhibitrice de l' α-glucosidase, antioxydantes (DPPH, FRAP, ORAC), antimicrobiennes et l'une (Bridelia ferruginea) une activité cytotoxique sur les cellules cancéreuses (PA1, MCF7, PC3, DU-145), avec une efficacité variable d'une plante à une autre. La quatrième partie discute de manière générale des résultats issus des études phytochimiques et des tests biologiques. Parmi les quatre échantillons de plantes sélectionnées pour notre étude, seul l'extrait semi-éthanolique des racines de Ceiba pentandra a une faible teneur en familles de composés dosés et présente des activités biologiques (ci-dessus citées) faibles comparativement aux extraits de Bridelia ferruginea, de Pseudocedrela kotschyi et de Polygonum senegalensis. L'ensemble des résultats tant sur le plan chimique que biologique met en évidence les potentialités des extraits de plantes étudiées, pour une exploitation à des fins thérapeutiquesfuturesThe present work had reported on the phytochemical and biological studies of non-volatile extracts of four plants used in Benin for diabetes treatment. The first part reviewed the bibliography of investigated plants in our study. In this part, the systematic, the importance in the pharmacopoeia and the previous works done on these plants were presented. The second part has presented the extraction method and chemical studies of the extracts and results obtained. The spectrophotometry has permitted to identify some important families of compounds in the extracts: the total polyphenols, flavonoids and tannins whereas the GC / MS and LC/MS were used to highlight the presence of volatile and non-volatile compounds. The third part described the biological tests in vitro and ex vitro carried out on the extracts. The extracts showed in general activities: α-glucosidase inhibition, antioxidant (DPPH, FRAP, ORAC), antimicrobial, and one of them (Bridelia ferruginea) were cytotoxic on cancer cells (PA1, MCF7, PC3, DU-145), with a variable efficiency from one plant to another. The fourth part had discussed in general about the results obtained from phytochemical studies and biological tests. Among the four plants samples selected for our study, only the semi-alcoholic extract of Ceiba pentandra roots had a low-dosed compounds families and presented of this biological activities (cited below) low comparatively to Bridelia ferruginea, Pseudocedrela kotschyi and Polygonum senegalensis extracts. Both of the chemical and biological results highlight the potential of certain species for future exploitation of their non-volatile extract for therapeutic purposes
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Shai, LJ, JN Eloff, N. Boaduo, AM Mogale, SR Magano, MP Mokgotho, and P. Masoko. "Yeast alpha glucosidase inhibitory and antioxidant activities of six medicinal plants collected in Phalaborwa, South Africa." Elsevier, 2010. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1001248.
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Abstract
Recent decades have experienced a sharp increase in the incidence and prevalence of diabetes mellitus. One antidiabetic therapeutic
approach is to reduce gastrointestinal glucose production and absorption through the inhibition of carbohydrate-digesting enzymes such as α-
amylase and α-glucosidase and α-amylase. The aim of the current study was to screen six medicinal plant species, with alleged antidiabetic
properties for α-glucosidase inhibitory activities. Powdered plant materials were extracted with acetone, and tested for ability to inhibit baker's
yeast α-glucosidase and α-amylase activities. The largest mass (440 mg from 10 g) of the extract was obtained from Cassia abbreviata, while
both Senna italica and Mormordica balsamina yielded the lowest mass of the extracts. Extracts of stem bark of C. abbreviata inhibited baker's
yeast α-glucosidase activity with an IC50 of 0.6 mg/ml. This plant species had activity at low concentrations, with 1.0 mg/ml and above
resulting in inhibition of over 70%. The other five plant extracts investigated had IC50 values of between 1.8 and 3.0 mg/ml. Senna italica only
managed to inhibit the activity of enzyme-glucosidase at high concentrations with an IC50 value of 1.8 mg/ml, while Tinospora fragosa extracts
resulted in about 55% inhibition of the activity of the enzyme at a concentration of 3.5 mg/ml, with an estimated IC50 value of 2.8 mg/ml.
The bark extract of C. abbreviata was the most active inhibitor of the enzyme, based on the IC50 values (0.6 mg/ml). The bark extract of C. abbreviata
contains non-competitive inhibitor(s) of α-glucosidase, reducing Vmax value of this enzyme from 5 mM·s–1 to 1.67 mM·s–1, while Km remained
unchanged at 1.43 mMfor para-nitrophenyl glucopyranoside. Antioxidant activity of the extracts was also investigated. The C. abbreviata extract was
more active as an antioxidant than the positive control, trolox. The extracts did not inhibit alphaamylase activity more than about 20% at the highest
concentration tested.
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Giudicelli, Jean. "L'alpha-glucosidase neutre : structure et fonction de la protéine." Paris 11, 1988. http://www.theses.fr/1988PA112140.
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L’ α-D-glucosidase neutre du rein de cheval (α -D-glucoside glucohydrolase EC 3. 2. 1. 20) a été purifiée sous une forme protéolytique par chromatographie d’ affinité. Les propriétés moléculaires, immunologiques et catalytiques de l'enzyme ont été déterminées. Un modèle minimum décrivant le fonctionnement du site actif a été proposé. L' enzyme a également été purifiée sous sa forme intégrale, sa nature amphipatique a été clairement établie. L’étude de la susceptibilité de la protéine vis-à-vis de différentes enzymes protéolytiques a permis de démontrer que l' α -D-glucosidase neutre possède un peptide intermédiaire de 2 à 5 nm. Une technique de préparation de protéoliposomes, constitués par des lécithines et des protéines intégrales de la membrane de bordure en brosse du rein de cheval, a été mise au point. Cette méthode permet d’obtenir des vésicules qui ont conservé les caractéristiques essentielles du transport du glucose et de la L-alanine, notamment la dépendance vis-à-vis des ions sodium. Cette méthode permet d'insérer l' α-D-glucosidase neutre sous sa forme intégrale, seule ou en association avec d'autres protéines. Une intégration asymétrique de la protéine, dans l'orientation qu'elle possède au sein de la membrane native ainsi qu' une topologie identique sont retrouvées dans les protéoliposomes formés. L'utilisation de ce modèle artificiel permet d'étudier le rôle de l'enzyme dans le transport du glucose. Les résultats obtenus avec du glucose libre ou du glucose produit par hydrolyse du maltose démontrent l'absence de toute participation de cette protéine dans le transfert transmembranaire de ce solutéNeutral a-0-glucosidase which is purified after solubilization by Triton X-100 can easely be integrated in artificial vesicles. The fact that this enzyme bound to native and artificial membrane vesicles, exhibited the same antibodies-binding which is equivalent to that of the proteolytic form, demonstrated the free accessibility of the antigenic sites to specific antibody. Neutral a-0-glucosidase activity, associated with both membrane system, presented the same single activation energy and a Q10 as that observed for the proteolytic form of the enzyme, over the temperature range studied. This result which could be correlated with the external location of the bulk of the hydrophilic part of the enzyme was confirmed by proteolytic treatments using proteinases of various shapes. Findings allow us to conclude that the topology of the enzyme integrated in artificial membrane vesicles is the same as that of the native membrane bound enzyme. Horse kidney Neutral a-0-glucosidase integrated in native membranes or in proteoliposomes exhibited its hydrophilic part separated, out of the membrane surfaces, by a 2-5 nm junctional polypeptide segment
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Chen, Xian Qiang. "Study on the chemical constituents of ganoderma resinaceum and their α-glucosidase inhibitory activities." Thesis, University of Macau, 2018. http://umaclib3.umac.mo/record=b3952488.
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Nguyen, The Dương, Thanh Hoang Le, and Thi Tuyen Do. "Optimization of culture medium for the cultivation of Actinoplanes sp. mutant strains and purification of acarbose." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-227839.
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In order to improve the production of acarbose, the fermentation medium of acarbose-producing strain Actinoplanes sp. KCTC 9161 – L14 mutant was optimized in this internship. Fractional factorial design was employ to investigate the influences of glucose, maltose and corn power on acarbose production (by a-glucosidase inhibitory ability). Two significant factors: glucose and maltose have significant and positive effects on acarbose amount. In addition, a model was obtained from the regression results of fractional factorial experiment. Other success, we demonstrated that chromatography by active charcoal column can used to purify acarbose from fermentation broth. Acarbose amount in purification solution was 191.5 g/L and an acarbose - purification process was inductedNhằm mục đích nâng cao khả năng sinh tổng hợp hoạt chất acarbose từ chủng đột biến Actinoplanes sp. KCTC 9161-L14, môi trường lên men của chủng dùng để sản xuất acarbose đã được tối ưu hóa. Một phần mềm thiết kế đã được thiết lập để khảo sát ảnh hưởng của glucose, maltose và bột ngô đến khả năng sản xuất acarbose (thông qua hoạt tính ức chế a-glucosidase). Kết quả đã cho thấy, hai yếu tố glucose và maltose có ý nghĩa quan trọng và ảnh hưởng trực tiếp đến khả năng sinh tổng hợp acarbose. Một phương trình đã được hình thành từ kết quả tối ưu. Bên cạnh đó, chúng tôi đã chứng minh được cột sắc ký sử dụng than hoạt tính có thể tinh sạch acarbose từ dịch lên men. Hàm lượng acarbose trong dung dịch tinh sạch đạt 191,5 g/l và một quy trình tinh sạch acarbose được đề xuất
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Ryan, Caroline Mary. "Anti-Diabetic and Anti-Obesity Activities of Cocoa (Theobroma cacao) via Physiological Enzyme Inhibition." Thesis, Virginia Tech, 2016. http://hdl.handle.net/10919/75003.
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Fermentation and roasting of cocoa (Theobroma cacao) decrease levels of polyphenolic flavanol compounds. However, it is largely unknown how these changes in polyphenol levels caused by processing affect cocoa's anti-diabetic and anti-obesity bioactivities, such as inhibition of certain enzymes in the body. Polyphenol profiles, protein-binding abilities, presence of compounds termed oxidative polymers, and abilities to inhibit α-glucosidase, pancreatic α-amylase, lipase, and dipeptidyl peptidase-IV (DPP4) in vitro were compared between unfermented bean (UB), fermented bean (FB), unfermented liquor (UL), and fermented liquor (FL) cocoa extracts. Overall, there were significant decreases (p<0.05) in total polyphenols, flavanols, and anthocyanins between the two sets of unfermented and fermented cocoa extracts (CEs). All CEs effectively inhibited α-glucosidase (lowest IC50 = 90.0 ug/mL for UL) and moderately inhibited α-amylase (lowest IC50=183 ug/mL for FL), lipase (lowest IC25=65.5 ug/mL for FB), and DPP4 (lowest IC25=1585 ug/mL for FB) in dose-dependent manners. Fermentation and roasting of the samples affected inhibition of each enzyme differently (both processes enhanced α-amylase inhibition). Improved α-glucosidase and α-amylase inhibitions were correlated with presence of different classifications of oxidative polymers, suggesting that these compounds could be contributing to the bioactivities observed. Some α-glucosidase inhibition might be due to non-specific protein-binding. Improved DPP4 inhibition was strongly correlated to increased CE degree of polymerization. In conclusion, potential enzyme inhibition activities of cocoa were not necessarily negatively affected by the large polyphenol losses that occur during fermentation and roasting. Additionally, it is possible that more complex compounds could be present in cocoa that contribute to its potential anti-diabetic and anti-obesity bioactivities.Master of Science in Life Sciences
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Hogan, Shelly Patricia. "Grape Extracts for Type 2 Diabetes Treatment Through Specific Inhibition of α-Glucosidase and Antioxidant Protection." Diss., Virginia Tech, 2009. http://hdl.handle.net/10919/26725.
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Research was conducted to investigate the effect of phenolic compounds derived from inherently rich antioxidant grape extracts (GE) on α-glucosidase inhibitory activity in vitro and in vivo blood glucose control, oxidative stress, and inflammation associated with obesity-induced type 2 diabetes. Because intestinal α-glucosidase plays a key role in the digestion and absorption of complex carbohydrates, the inhibition of this enzyme is a metabolic target for managing diabetes by improving post-prandial blood glucose control. Initially, red Norton wine grape (Vitis aestivalis) and pomace extracts were evaluated and determined to have notable phenolic content and antioxidant properties. Next, grape skin (GSE) and pomace extract (GPE) were tested and both had in vitro yeast and mammalian α-glucosidase inhibitory activity. The GSE was 32-times more potent at inhibiting yeast α-glucosidase than acarbose, a commercial oral hypoglycemic agent. From HPLC and LC-MS analysis, three phenolics from the GSE (resveratrol, ellagic acid, and catechin) were identified as active inhibitory compounds. The acute administration of GPE (400 mg/kg bw) to mice reduced postprandial blood glucose level by 35% following an oral glucose tolerance test compared to the control. The daily supplementation (250 mg/kg bw) of GSE and GPE for 12-weeks to mice affected fasting blood glucose levels, oxidative stress, and inflammatory biomarkers associated with obesity and type 2 diabetes. At the end of the study, the GSE group gained significantly (P < 0.05) more weight (24.6 g) than the control, high fat, or GPE groups (11.2, 20.2, 19.6 g, respectively). Both GSE and GPE groups had lower fasting blood glucose levels (119.3 and 134.2 mg/dL, respectively) compared to the high fat group (144.6 mg/dL). The 12-week supplementation of GSE was associated with a higher plasma oxygen radical absorbance capacity (ORAC), lower liver lipid peroxidation as measure by TBARS, and lower levels of inflammation as measured by plasma C-reactive protein compared to the high fat group. In conclusion, our collective observations from these studies provide insight into the potential effects of antioxidant rich grape extracts on diabetes-related biomarkers through a dual mechanism of antioxidant protection and specific inhibition of intestinal α-glucosidases.Ph. D.
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Albert, Heidemarie. "Studies on the α-glucosidase enzyme of Bacillus stearothermophilus, ATCC 7953, a biological indicator test organism." Thesis, University of Bath, 1995. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.295444.
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Pacheco, Simone Muniz. "Frutos da família Myrtaceae: Caracterização físicoquímica e potencial inibitório da atividade das enzimas digestivas." Universidade Federal de Pelotas, 2015. http://repositorio.ufpel.edu.br:8080/handle/prefix/3055.
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Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq
As espécies vegetais Campomanesia xanthocarpa (guabiroba), Eugenia uniflora (pitanga), Eugenia pyriformis (uvaia), Psidium cattleianum (araçá) e Syzygium cumini (jambolão) estão presentes na Floresta Atlântica e são utilizadas pela população, para tratar diversas patologias, especialmente o diabetes melito tipo 2. Entretanto, a eficácia destes tratamentos e o mecanismo envolvido ainda não foram totalmente elucidados. Neste contexto, o presente estudo teve como objetivo principal avaliar o potencial dos compostos naturais destes frutos em inibir as enzimas α-amilase e α- glicosidase que estão envolvidas no metabolismo de carboidratos. Estes frutos também foram avaliados físico-quimicamente, realizando-se dentre outras análises a quantificação dos compostos fenólicos totais e a determinação da atividade antioxidante (métodos ABTS e DPPH). Os extratos metanólicos de P. cattleianum (acesso 44), S. cumini e E. pyriformis (acessos 11 e 15) inibiram de forma significativa a atividade da α-amilase. Os extratos metanólicos de P. cattleianum (acessos 44 e 87) também inibiram a atividade da α-glicosidase, utilizando-se os substratos maltose e sacarose. Em virtude da atividade antioxidante, da elevada quantidade de compostos fenólicos e da capacidade de inibição das enzimas digestivas do metabolismo de carboidratos, os frutos de P. cattleianum (acessos 44 e 87), S. cumini e E. pyriformis (acessos 11 e 15) podem apresentar potencial uso no manejo da hiperglicemia pós-prandial.
Campomanesia xanthocarpa (guabiroba), Eugenia uniflora (pitanga), Eugenia pyriformis (uvaia), Psidium cattleianum (araçá) and Syzygium cumini (jambolão) grow in the Brazilian Atlantic Forest and their fruits are commonly used as medicine to treat diseases related to carbohydrate metabolism, such as diabetes. The effectiveness of these treatments has not been demonstrated neither the biochemical mechanism involved. Therefore this study was devised to evaluate the potential of natural compounds of these fruits to inhibit key enzymes α-amylase and α- glucosidase involved in the carbohydrate metabolism. The fruits were also subjected to physicochemical characterization, quantification of phenolics compounds and antioxidant activity (ABTS and DPPH methods). The methanolic extracts of P. cattleianum (access 44), S. cumini, E. pyriformis (accesses 11 and 15) distinctively inhibited α-amylase activity. The methanolic extracts of P. cattleianum. (accesses 44 and 87) also inhibited α-glycosidase activity, with either maltose or sucrose as substrate. By having antioxidant activities, a fairly content of phenolic compounds, and capacity to inhibit carbohydrate digestive enzymes, P. cattleianum (access 44 and 87), S. cumini and E. pyriformis (accesses 11 and 15) could be good candidates to be used in the management of postprandial hyperglycemia.
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OKUMURA, NOBUYOSHI, TAKAHARU KONDO, AIJI NODA, and TETUO HAYAKAWA. "Effects of Acarbose, an α-Glucosidase Inhibitor (BAY G 5421), on Orally Loaded Glucose, Maltose and Sucrose and on Blood Glucose Control in Non-Insulin-Dependent Diabetics." Nagoya University School of Medicine, 1985. http://hdl.handle.net/2237/17475.
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Sibanda, Ntsako. "Evaluation of high recombinant protein secretion phenotype of saccharomyces cerevisiae segregant." Thesis, University of Limpopo, 2016. http://hdl.handle.net/10386/1803.
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Thesis (MSc. (Biochemistry)) --University of Limpopo, 2016The ever increasing cost of fossil-based fuels and the accompanying concerns about their impact on the environment is driving research towards clean and renewable sources of energy. Bioethanol has the potential to be a replacement for liquid transportation fuels. In addition to its near zero nett carbon dioxide emissions, bio-ethanol has a high energy to weight ratio and can easily be stored in high volumes. To produce bioethanol at economically competitive prices, the major cost in the production process needs to be addressed. The addition of enzymes to hydrolyse the lignocellulosic fraction of the agricultural waste to simple sugars is considered to be the major contributor to high production cost. A consolidated bioprocess (CBP) which ideally combines all the steps that are currently accomplished in different reactors by different microorganisms into a single process step would be a more economically feasible solution. In this study the potential of yeast hybridization with a CBP approach was used. In order to evaluate the reduction or elimination of the addition of cellulolytic and hemi-cellulolytic enzymes to the ethanol production process. High cellobiohydrolase I secreting progeny from hybridization of an industrial bioethanol yeast strain, S. cerevisiae M0341, and a laboratory strain S. cerevisiae Y294 were isolated. In order to determine if this characteristic was specific to cellobiohydrolase I secretion, these strains were evaluated for their ability to secrete other relevant recombinant hydrolase enzymes for CBP-based ethanol production. A total of seven S. cerevisiae strains were chosen from a progeny pool of 28 supersecreting hybrids and reconstructed to create two parental strains; S. cerevisiae M0341 and S. cerevisiae Y294, together with their hybrid segregants strains H3M1, H3M28, H3H29, H3K27 and H3O23. Three episomal plasmids namely pNS201, pNS202 and pNS203 were constructed; these plasmids together with two already available plasmids, namely pRDH166 and pRDH182 contained genes for different reporter enzymes, namely β-glucosidase I, xylanase II, endoglucanase lll, cellobiohydrolase l and α-glucuronidase. To allow for selection of the episomal plasmids, homologous recombination was used to replace the functional URA3 gene of selected strains, with the non-functional ura3 allele from the Y294 strain. Enzyme activity was used as an indicator of the amount of enzyme secreted. Fermentation studies in a bioreactor were used to determine the metabolic burden imposed on the segregants expressing the cellobiohydrolase at high levels. In addition all segregants were tested for resistance to inhibitors commonly found in pre-treated lignocellulosic material. The M28_Cel7A was found to be the best secretor of Cel7A (Cellobiohydrolase l); however it seems as though this phenomenon imposes a significant metabolic burden on the yeast. The supersecreting hybrid strains cannot tolerate lignocellulosic inhibitors at concentrations commonly produced during pretreatment
The National Research Foundation - Renewable Energy Scholarship (NRF-RSES)
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Matrose, Albertina Neliswa. "Evaluation of the antioxidant and anti-diabesity potential of cyclopia maculata using in vitro non-cell based screening models." Thesis, University of the Western Cape, 2014. http://hdl.handle.net/11394/4262.
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Masters of ScienceThe aim of this study was therefore to evaluate the antioxidant and anti-diabesity potential of a hot water extract of C. maculata in non-cell based assays and correlate the activities with phenolic composition. Total antioxidant capacity (TAC) was assessed in terms of free radical scavenging and iron reducing ability. The DPPH, ABTS, ORAC and FRAP assays were employed. Anti-diabesity potential was assessed in terms of the inhibition of the digestive enzymes, α-glucosidase and pancreatic lipase
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Caputo, Alessandro T. "Structural and biochemical characterisation of the endoplasmic reticulum α-glucosidases." Thesis, University of Oxford, 2015. https://ora.ox.ac.uk/objects/uuid:9c522ff4-5d7a-4815-96e6-44007ec7b7c3.
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ER alpha-glucosidases I and II are glycosyl hydrolases that play a key role in eukaryotic glycoprotein folding quality control. Removal of two glucose residues from the N-glycan attached to a protein allows association with calnexin or calreticulin which enable folding through associated accessory proteins. Many enveloped viruses utilise the calnexin cycle for the correct folding of their surface glycoproteins. Inhibition of the ER alpha-glucosidases causes misfolding of these viral glycoproteins and reduction of virion secretion and/or infectivity. Thus, inhibition of these glucosidases is a potential broad-spectrum antiviral strategy with clinical relevance. Inhibition by certain iminosugars, a class of glycomimetics, has given rise to a clinical candidate against dengue virus. To date there are no high-resolution structures available for either of the mammalian ER alpha-glucosidases. Presented in this thesis is the work toward the structural and biochemical characterisation of both alpha-glucosidases. Large-scale production of both murine glucosidases is described along with biochemical characterisation against a number of substrates. Glucosidase I is a challenging target for biochemical and structural studies. Described is the purification and confirmation of enzymatic activity. Biophysical techniques show that it is well folded and able to bind to iminosugars. Preliminary attempts at crystallisation have resulted in poorly diffracting crystals to 5 Å. This work enables future optimisation toward an atomic resolution structure of glucosidase I. Glucosidase II plays a complex role in the kinetics of glycoprotein processing in the calnexin cycle. Production of the heterodimeric enzyme has enabled a detailed biochemical characterisation with a range of substrates and inhibitors. Structural characterisation of a large fragment of glucosidase II has enabled new insights into the details of heterodimerisation, substrate specificity, and the basis of iminosugar inhibition. This information can guide future development of more selective inhibitors.
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Huang, Yu-Zhan, and 黃鈺展. "Daidzein and Genistein Obtained from The Digestion of Isoflavon Glucoside Conjugate by β-glucosidase of Lactic Acid Bacteria Inhibit α-glucosidase Activities." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/2g5hxn.
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碩士實踐大學
食品營養與保健生技學系碩士班
103
Soy isoflavones comprises of glycosidic isoflavones and isoflavone aglucones. The glycosidic isoflavones are formed by β-linkage of aglucone with any glycosides. Previous studies have shown that lactic acid bacteria with a cell surface enzyme β- glucosidase may be able to hydrolyze the β glycosidic bond, including isoflavone glycosides, and produces glucose and the aglucones. Daidzein has been proved as an α- glucosidase inhibitor, may reduce the absorption of glucose. However, the inhibition mechanism is not clear. Furthermore, no evidence has shown the effectiveness of the use of lactic acid and soy isoflavone composition on α- glucosidase inhibition. Therefore, this study is to study: (1) α- glucosidase enzyme kinetics by Michaelis-Menten equation, Lineweaver-Burk plot to obtaine α- glucosidase Vmax and Km, (2) the inhibiton mechanism ofα- glucosidase by glucosidic isoflavone, daidzin and genstin, and aglucone, daidzein, genstein, respectively, (3) the effect of the fermentation broth of a lactic acid bacteria and soy isoflavone composition on α- glucosidase enzyme inhibition. The results show that: (1) the mechanism of α- glucosidase enzyme inhibition by isoflavone is uncompetitive inhibition, (2) α- glucosidase inhibition rate of aglcone genistein, daidzein is significantly greater than that of glucosidic isoflavone genistin, daidzin, (3) the fermentation broth of Lactobacillus casei A39 and soy isoflavone composition, which containing a higher genistein, daidzein concentration, shows a significant inhibition of α- glucosidase activity than that of unfermented group. Taken together, this study demonstrated that β-glucosidase of lactic acid cell surface can hydrolyze isoflavone glycoside and produces aglucones, daidzein and genistein, which may be able to effectively inhibit α- glucosidase activity, and belongs to an uncompetitive inhibition mechanism; furthermore, lactic acid bacteria and soy isoflavones together, may be used as a hypoglycemic or obesity prevention food composition.
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Chang, Chiung-Chieh, and 張瓊潔. "Inhibition of α-Glucosidase and α-Amylase from the Hydrolysate of Laminaria japonica." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/84283481024465836137.
Full textAbstract:
碩士國立臺灣海洋大學
食品科學系
99
The inhibitory effect of Laminaria hydrolysates (hydrolyzed by cellulase and protease) and fermented hydrolysates (fermented with mixed lactic acid bacteria) on α-glucosidase and α-amylase ,and in vitro of bile acid binding capacity were investigated. The yield of hydrolysate increased from 21.4 to 37.8%, as adding 5 or 10% cellulase and 2% protease in the Laminaria. The total carbohydrate and peptide content of Laminaria hydrolysates were increased from 229.4 to 418.9 mg/g and from 5.3 to 88.7 mg/g, respectively, as the hydrolysis time from 3 to 9 h. The inhibition of hydrolysate (hydrolysis for 3 h) on α-glucosidase and α-amylase IC50 were 17.0 and 45.4 mg/mL, respectively. This hydrolysate was separated by ultrafiltration using 5000 Da membranes, and its α-glucosidase IC50 was 10.4 mg/mL. The yield of hydrolysates was increased from 30.1 to 58.4%, and total carbohydrate content was increased from 340.4 to 400.6 mg/g. The fermented hydrolysate on α-glucosidase and α-amylase IC50 were 22.4 and 29.8 mg/mL, respectively. This hydrolysate was separated into two fractions by size exclusion chromatography on a Sephadex-15 column. The second fraction showed the highest α-glucosidase inhibitory efficiency ratio (IER) as base on carbohydrate and peptide compound being 7.2 and 45.3 %/mg/mL. The bile acid binding capacity of Laminaria powder (whole Laminaria, hydrolysates residue and fermented hydrolysates residue) were 9.7, 11.7 and 10.7%, respectively, as compared to cholestyramine.
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Chan, Meng-Han, and 詹孟翰. "α-Glucosidase inhibitory effect by the extract ofAntrodia cinnamomea." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/02762973528853811650.
Full textAbstract:
碩士中國文化大學
生物科技研究所
102
Epidemiological studies indicate that diabetes two indicators on blood sugar balance , one is fasting glucose, another is postprandial glucose level. Postprandial glucose level is more important to control blood sugar after a meal, when α-glucosidase inhibitors would reduce its effect. Taking the α-glucosidase inhibitors to manage blood glucose level result in hypoglycemic symptoms of gastrointestinal discomfort,and many studies have pointed out the synthestic of α-glucosidase inhibitors may would increase kidney tumors, severe liver injury and the occurrence of acute hepatitis rate. Antrodia was known of many active ingredients with anti-cancer, leukemia and pancreatic cancer, increased immunity, allergy, and blood pressure, and blood glucose lowering effect. According to the results of this study indicate Antrodia broth and mycelium of Antrodia show respectively 318 and 380 mg/ml inhibitory effect. On α-glucosidase activity and the inhibitory effect of the fermented liquid is how even higher than that of the mycelium, compared to other naturak herbs.excessive doses needed who found in Antroidia, it is less suitable an excellent α-glucosidase inhibitor than connent found onto.
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LIN, PIN-YU, and 林品妤. "α-Amylase and α-Glucosidase Inhibitory and Antioxidant Activitiesof the Extracts from Antrodia cinnamomea." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/5pe8xd.
Full textAbstract:
碩士中國文化大學
生物科技研究所
104
Nowadays, the percentage of mortality caused by diabetes has reanked to the fifth among the top ten leading death, stimalating research on the prevention of this disease. Drug treatment to diabities , although it lowers blood sugar, may cause side effects and patient death. In this study, Antrodia mycelia and broth were used as samples , and extracted by water, 50% ethanol, 75% ethanol extraction. The inhibitory activity for alpha-glucosidase, antioxidant activity , the total polyphenol content, DPPH scavenging assay, reducing power assay .The results show that IC50 of water extraction of the fermentation broth is very close to the IC50 acarbose. The polyphenol content also show the best result .The result indicated that Antrodia broth is potential for used as alpha-glucosidase inhibitor. Keywords: Antrodia cinnamomea、alpha-glucosidase, reducing power assay, DPPH scavenging assay，Total polyphenol content
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Barker, Megan. "Structural Investigation of Processing α-Glucosidase I from Saccharomyces cerevisiae." Thesis, 2010. http://hdl.handle.net/1807/32660.
Full textAbstract:
N-glycosylation is the most common eukaryotic post-translational modification, impacting on protein stability, folding, and protein-protein interactions. More broadly, N-glycans play biological roles in reaction kinetics modulation, intracellular protein trafficking, and cell-cell communications.
The machinery responsible for the initial stages of N-glycan assembly and processing is found on the membrane of the endoplasmic reticulum. Following N-glycan transfer to a nascent glycoprotein, the enzyme Processing α-Glucosidase I (GluI) catalyzes the selective removal of the terminal glucose residue. GluI is a highly substrate-specific enzyme, requiring a minimum glucotriose for catalysis; this glycan is uniquely found in biology in this pathway. The structural basis of the high substrate selectivity and the details of the mechanism of hydrolysis of this reaction have not been characterized. Understanding the structural foundation of this unique relationship forms the major aim of this work.
To approach this goal, the S. cerevisiae homolog soluble protein, Cwht1p, was investigated. Cwht1p was expressed and purified in the methyltrophic yeast P. pastoris, improving protein yield to be sufficient for crystallization screens. From Cwht1p crystals, the structure was solved using mercury SAD phasing at a resolution of 2 Å, and two catalytic residues were proposed based upon structural similarity with characterized enzymes. Subsequently, computational methods using a glucotriose ligand were applied to predict the mode of substrate binding. From these results, a proposed model of substrate binding has been formulated, which may be conserved in eukaryotic GluI homologs.
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Hsieh, Po-Hung, and 謝伯鴻. "Preparation of acylated rhamnosyl flavonoid analogs as α-glucosidase inhibitors." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/69039746844570768891.
Full textAbstract:
碩士國立臺灣大學
藥學研究所
96
α-Glucosidase inhibitors (AGH) are one type of oral antihyperglycemic drugs targeting on the enzymes in the small intestine. They block the metabolism of the carbohydrates and lower postprandial glucose level to achieve therapeutic control of diabetes. According to the recent finding of natural flavonol O-acylated rhamnosides to be potent α-glucosidase inhibitors, the structure and activity relationship of such type compounds were explored in this study. Pinitol and hesperidin were chosen as starting materials. Esterification and etherification were undertaken to prepare a series of phenylpropenoyl- and O-phenylpropenyl- pinitols, and hesperidin derivatives. The corresponding non-conjugated derivatives of these compounds were also prepared via catalytical hydrogenation. Bioassay against α-glucosidase showed that cinnamyl- and dihydrocinnamyl- pinitols have no inhibitory activity. However, they could enhance insulin to stimulate glucose uptake, especially compound IIC-4. Dihydro-1,2-seco-hesperidin (IVA-2) showed weak inhibition activity; nevertheless, etherification with cinnamyl bromide at 2-position of the glucosyl residue could increase activity (IVA-4, IC50 = 136.8 uM). Intravenous glucose tolerance test on normal rats indicated that compound IB-1 could reduce the blood glucose level significantly. This could be attributable to the function of pinitol and cinnamic acid, the hydrolytic products of IB-1. The bioactivity of O-cinnamyl- and O-dihydrocinnamyl- hesperidins remains to be disclosed.
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Ze, Chen Chu, and 陳楚澤. "Xanthine Oxidase and α-Glucosidase Inhibition of Curcumin and Curcumin Analogs." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/y83s8x.
Full textAbstract:
碩士輔仁大學
食品科學系碩士班
103
Curcumin is a constituent from root and stem of family Zingiberaceae and Araceae. It has been used as a natural colorant in food industry. Curcumin has a great value in food and medicine, and it has been reported that curcumin could inhibit the activities of xanthine oxidase (XO) and α-glucosidase that make curcumin can be used for treatment of gout and diabetes. Chemical synthesis, which can change the structure of component, can enhance the activities, even create a new one. Therefore, the objective of this research is to evaluate the characterization of curcumin and its analogs as XO and α-glucosidase inhibitors. In this study, after screening XO and α-glucosidase inhibition, the components which have high inhibitory activities were calculated their half-maximal inhibitory concentration (IC50) and enzyme inhibitory kinetics. In order to calculating the inhibitory reaction constant, a docking algorithm simulates binding position between enzyme and inhibitors. The results showed that among all the curcumin and its analogs, CM-F had the strongest anti-oxidant activity with a half-maximal effective concentration (EC50) of 9.39 ± 0.16 μM, which was better than vitamin E (EC50=17.03 ± 0.09 μM). It also had a good XO inhibitory activity, and its IC50 value against XO was 6.14 ± 0.38 μM. The enzyme kinetic result showed it was competitive inhibition. As for α-glucosidase, CM-1 and CM-2 have good α-glucosidase inhibitory activities with the IC50 value of 21.06 ± 0.92 μM and 5.95 ± 0.09 μM, of which kinetic study indicates that both CM-1 and CM-2 are mix-competitive inhibitors on α-glucosidase. Furthermore, docking simulation showed there are 5 hydrogen bonds between XO and CM-F. However, only 1 and 2 hydrogen bonds involved in CM-1 and CM-2 binding to α-glucosidase, respectively. Accordingly, analogs of curcumin have the potentials using in the gout or diabetes patients.
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Wu, Ying, and 巫熒. "Inhibition of α-Glucosidase and α-Amylase and Purification of Bioactive Substances from Hydrolysate of Chlorella sorokiniana." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/56955602391290481785.
Full textAbstract:
碩士國立臺灣海洋大學
食品科學系
97
The inhibitory effect of Chlorella sorokiniana hydrolysates (hydrolyzed by cellulase and protease) on activity of α-glucosidase and α-amylase were investigated. When adding of 5% cellulase and 2% protease in the three Chlorella hydrolysates (pulverized cell, unpulverized cell and residue), the hydrolysate (pulverized cell) showed the highest yield being 42.0% after hydrolysis for 3 h. As the hydrolysates (pulverized cell) were hydrolyzed for 5 h, the peptide and free amino acid content of Chlorella hydrolysates (pulverized cell) were increased from 236.6 to 304.0mg/g and from 34.4 to 61.1mg/g, respectively. As hydrolysis for 3 h, the hydrolysate had the highest inhibition on α-glucosidase (IC50＝26.4 mg/mL) and α-amylase (IC50＝20.7 mg/mL). And, total polyphenol content (24.8mg/g) reached the highest value. The hydrolysate (pulverized cell) was separated into four fractions by size exclusion chromatography on a Sephadex-15 column. The fourth fraction (M.W.=370-280Da) of the hydrolysate showed the highest α-glucosidase inhibitory efficiency ratio (IER) in carbohydrate, peptide and polyphenol compound as base, which were 126.4, 122.0 and 316.1 %/mg/mL. The fourth fraction was further analyzed by HPLC, only peak Ⅳ-1 had inhibitory effect on α-glucosidase and its IER was 1027.8 %/mg/mL.
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Hung, Wen-Yung, and 洪文詠. "Effect on Inhibition of α-Glucosidase and α-Amylase from Hydrolysate of Chlorella sorokiniana and Freshwater Clam." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/81405601204584401428.
Full textAbstract:
碩士國立臺灣海洋大學
食品科學系
99
The domestic cultivated Chlorella sorokiniana as a material , the inhibitory effects of α-glucosidase and α-amylase of Chlorella sorokiniana hydrolysates (hydrolyzed by cellulase and protease) were investigated, and purified bioactive substances from hydrolysate having the highest α-glucosidase and α-amylase inhibitory activity to evalvate the physiological effect on regulation of blood sugar. When adding 5% cellulase and 2% protease in the Chlorella hydrolysates (pulverized cell), hydrolysed for 3 h, the soluble protein, carbohydrate, and total polyphenol contents was 641、227 and 25 mg/g, repectively. To explore glycosidase inhibition from different sources, the hydrolysate had better inhibition on yeast from (Saccharomyces cerevisiae) (IC50＝26.5 mg/mL), but on α-amylase from porcine pancreas, (IC50＝14.3 mg/mL). Then, the hydrolysate (pulverized cell) was separated into five fractions by size exclusion chromatography on a Sephadex-15 column. The C2 fraction (M.W.=370-280Da) of the hydrolysate showed the lowest α-glucosidase IC50 being 3.23 mg /mL. The C2 fraction was further analyzed by HPLC, only peak C2-1 had inhibitory effect on α-glucosidase and its IER was 542.9 %/mg/mL. The muscle of freshwater clam was extracted using hot water. The residual muscle was freeze dried then hydrolyzed by Protamex (PX) for 5 hr, the soluble protein, peptide, and carbohydrate contents was 596、160 and 360 mg/g, repectively. The inhibitory effects of freshwater clam hydrolysates (hydrolyzed by Protamex) on activity of α-glucosidase and α-amylase were investigated. The sources of the yeast AG and porcine pancreas AA had ad the higest α-glucosidase and α-amylase inhibitory activity (IC50＝14.6 and 11.9 mg/mL), repectively.
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Gago, Alexandre da Silva. "Compostos bioativos de microalgas com interesse no tratamento da diabetes." Master's thesis, 2016. http://hdl.handle.net/10400.1/8557.
Full textAbstract:
Dissertação de Mestrado, Biologia Molecular e Microbiana, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2016A diabetes é uma doença que afeta milhões de pessoas em todo o mundo e condiciona a qualidade de vida das mesmas. A diabetes tipo 2 tem merecido destaque pelo aumento da sua incidência e pelo facto de ser uma doença evitável. O tratamento atualmente resume-se a medicação específica juntamente com uma dieta bastante restritiva. As microalgas sendo conhecidas como tendo várias aplicações biotecnológicas, como a aquacultura e indústria farmacêutica, poderão ainda constituir uma fonte natural de compostos bioativos com propriedades antidiabéticas que poderão fornecer uma alternativa menos dispendiosa e com menos efeitos colaterais ao tratamento atual da diabetes tipo 2. Este trabalho visa avaliar as atividades biológicas de extratos orgânicos e aquosos preparados a partir de biomassa seca de Scenedesmus sp., nomeadamente antidiabética (inibição da α-amilase e α-glucosidase), antioxidante (captação dos radicais DPPH, ABTS e NO), quelante de ferro e de cobre e de inibição da lipase. Nos ensaios foi testado o extrato de etanol e frações resultantes do fracionamento em sílica do extrato etanólico. A fração 3A apresentou a maior atividade inibitória na α-glucosidase (IC50 = 0.29 mg/mL) e α-amilase (IC50 = 0.80 mg/mL). O extrato cru de etanol revelou maior atividade antioxidante, nomeadamente na capacidade de capturar os radicais DPPH (IC50 = 3.03 mg/mL) e ABTS (IC50 = 2.41 mg/mL). Esta fração foi também a que revelou maior atividade quelante para o ferro (IC50 = 1.10 mg/mL) e para o cobre (IC50 = 3.66 mg/mL). A composição química da fração 3A foi analisada por HPLC e GC-MS tendo-se identificado 6 compostos, nomeadamente, neofitadieno, fitol, ácido α-linolénico, ácido palmítico, ácido araquidónico e ácido palmitelaidico. Os resultados mostraram que a Scenedesmus sp. é uma boa fonte de compostos bioativos com aplicação no tratamento da diabetes. No entanto, será ainda necessária uma melhor caracterização química da fração ativa e identificar o ou os compostos responsáveis pela atividade antidiabética.
Diabetes is a disease that affects millions of people throughout the world and affects the quality of life of the same. Type 2 diabetes has been highlighted by its increasing incidence and in that it is a preventable disease. The treatment currently boils down to specific medication with a very restrictive diet. Microalgae have several biotechnological applications, such as aquaculture and pharmaceutical industry, and can be a natural source of bioactive compounds with anti-diabetic properties that can provide a less expensive alternative, with fewer side effects alternative to the current treatment of Type 2 Diabetes. This study aims to assess the biological activities of an ethanolic extract prepared from dried biomass of Scenedesmus sp., namely anti-diabetic (inhibition of the α-amylase and α- glucosidase enzymes), antioxidant (scavenging of radicals DPPH, ABTS and NO), chelation of the redox metals iron and copper and inhibition of lipase. In the experiments the crude ethanol extract was tested and fractions resulting from silica column fractionation. Fraction 3A showed the greatest inhibitory activity against α-glucosidase (IC50 = 0.29 mg/ml) and α- amylase (IC50 = 0.80 mg/ml). The crude ethanol extract showed a higher antioxidant activity given its higher capacity to scavenge the radicals DPPH (IC50 = 3.03 mg/ml) and ABTS (IC50 = 2.41 mg/ml). However, fraction 3A presented the higher chelating activity of iron (IC50 = 1.10 mg / ml) and copper (IC50 = 3.66 mg / ml). The chemical characterization of fraction 3A by HPLC and GC-MS resulted in the identification of 6 compounds (neophytadiene, phytol, α-linolenic acid, palmitic acid, arachidonic acid and palmitelaidic acid). These results show that Scenedesmus sp. is a promising source of bioactive compounds with applications in the treatment of Type 2 Diabetes. However, a better characterization of the chemical composition of the active fraction should be performed and the compound or compounds responsible for the anti-diabetic activity should be identified.
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Riyaphan, Jirawat, and Jirawat Riyaphan. "Virtual Screening of Natural Compounds or Products against α-glucosidase and α-amylase Activities for Lowering Blood Glucose." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/ebg5t5.
Full textAbstract:
博士國立東華大學
生命科學系
107
Type 2 diabetes mellitus (T2DM) is a chronic metabolic disorder in which the prevalence has been increasing steadily in worldwide. As a result, it is widespread rapidly caused by the gene, extra weight, and metabolism syndrome. The inhibition of α-glucosidase and α-amylase is an alternatively clinical treatment to delay the absorption of glucose in controlling hyperglycemia. The seeking new drugs from small molecules or natural compounds via virtual screening is crucial because the composition from some natural sources whether are targeted to the α-glucosidase and α-amylase as a hypoglycemic reagent still unexplored. The aim of the present study was to screen 53 natural compounds against α-glucosidase and α-amylase via molecular docking through Discovery Studio Visualizer version 3.5 software based on score function and docking energy. According to screened rank, ten natural compounds were selected. Further study attempted to evaluate the hypoglycemia efficacy of selected compounds via cellular and mouse levels. The results illustrated that the cytotoxicity in all tested compounds at various concentrations except the concentration of 16-hydroxy-cleroda-3,13-dine-16,15-olide (HCD) at 30 μM was not a significant difference (p> 0.05) when compared with the untreated control. Acarbose (reference drug), Antroquinonol, Catechin, Quercetin, Actinodaphnine, Curcumin, HCD, Docosanol, Tetracosanol, Berberine, and Rutin could effectively inhibit the α-glucosidase activity of Caco-2 cells when compared with the control (maltose). The compounds (Curcumin, HCD, Tetracosanol, Antroquinonol, Berberine, Catechin, Actinodaphnine, and Rutin) could reduce blood sugar level at 30 min in tested mice. The effects of tested compounds on the area under the curve (AUC) were significant (p < 0.05) among Acarbose, Tetracosanol, Antroquinonol, Catechin, Actinodaphnine, and Rutin along with Berberine and Quercetin. In in vitro (α-glucosidase) with in vivo (alpha-amylase), experiments suggest that bioactive compounds can be a potential inhibitor candidate of α-glucosidase and α-amylase for the alleviation of type II diabetes. The inhibition of glucosidase and amylase is a clinical strategy for the treatment of type II diabetes, and herbal medicines have been reported to credibly alleviate hyperglycemia. Our previous study has reported some constituents from plant or herbal sources targeted to glucosidase and amylase via molecular docking and enzymatic measurement, but the hypoglycemic potencies in cell system and mice have not been validated yet. The in vitro and in vivo studies were aimed to elucidate the hypoglycemic efficacy of docking selected compounds in cell assay and oral glucose and starch tolerance tests of mice. The result showed all test compounds could inhibit the glucosidase activity in Caco-2 cells. The OGTT and OSTT tests of mice showed the blood sugar levels of test compounds treatments were decrease significantly at 30 min and 60 min, and that varied with the effects of acarbose. Taken altogether, in vitro and in vivo experiments suggest that selected natural compounds (curcumin, antroquinonol, HCD, docosanol, tetracosanol, rutin, and actinodaphnine) via molecular docking were confirmed as potential candidates of glucosidase and amylase inhibitors for treating diabetes. Based on virtual screening data, the enzymatic assay, in vitro cell level and in vivo test are undergoing to do validate the screening results for confirming the efficacy of selected hits. This study will provide a clue for searching the hypoglycemic reagents for diabetes treatment and the new strategy for anti-diabetic drug discovery.
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Mao, Ying-Chun, and 毛瀅鈞. "Studies on α-Amylase and α-Glucosidase Inhibition and Anti-glycation Activities by Guava (Psidium guajava L.) Leaf Extracts." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/04093490044014034269.
Full textAbstract:
碩士國立嘉義大學
食品科學系研究所
101
In this study, guava (Psidium guajava L.) leaves were employed as the raw material, and were extracted by hot water and 4% hot acetic acid. The polyphenolic contents and antioxidant capability in the extract were determined and inhibitive activity of α-amylase, α-glucosidase and glycation were also evaluated. The results showed that the extract (4% acetic acid heated for 60 minutes at 90℃) was able to obtain the highest potency of totoal polyphenolic contents (3.04 mg/mL), condensed tannins (1.72 mg/mL) and total flavonoids (2.08 mg/mL) in the different resulting extract solutions, then the solution were freeze dried. The hot water extract had the highest total polyphenolic contents (265.36 mg/g), which presents good antioxidive activity: total antioxidant capability (IC50: 0.054 mg/mL) and DPPH free radical scavenging ability (IC50: 0.0091 mg/mL), respectively. All of the extracts had inhibitory activity of α-amylase and α-glucosidase. Among the extracts, 4% acetic acid heated for 60 minutes at 90℃ presented the best inhibitive activity of α-amylase (IC50: 1.88 mg/mL) and hot water extract showed the best inhibory activity of α-glucosidase (IC50: 0.002 mg/mL). The guava leaf extracts were subjected to the evaluation of in vitro glycation simulation. In BSA-Glucose system, guava leaf extracst had been observed to be capable of inhibiting Amadori products and the intermediate products, so it could effectively retard the occurrence of glycation and inhibit end-products formation. To confirm the inhibitory activities of α-amylase and α-glucosidase due to guava leaf extracts are related to the varieties and amounts of polyphenolic in the leaf extracts. Guava leaf hot water extract was further extracted by ethyl acetate; the phenolic contents in the ethyl acetate fraction was higher than that in hot water extract. In the solid concentration of 0.06 mg/mL and 0.01 mg/mL, the total antioxidant capability and DPPH radical scavenging ability of ethyl acetate fraction were 92.40% and 86.12%, respectively. The individually determined solid concentration of 2 mg/mL was able to inhibit α-amylase activity up to 60.98%; on the other hand, that of 0.002 mg/mL inhibits α-glucosidase activity up to 88.37%. Additionally, guava leaf ethyl acetate fraction had a better inhibitory activity of the intermediate products in the glycation reaction, leading to possible inhibition of end-products formation. The functional ingredients of guava leaf extract and ethyl acetate fraction were analyzed by HPLC. After compared with standards, the contents of gallic acid, (+)-catechin, (-)-epicatechin, (-)-epigallocatechin gallate, rutin, ellagic acid and quercetin were observed. The commercially produced standards of polyphenolic compounds that presents the guava were used to evaluate the antioxidant interactions; all of the combinations did not showed any significant synergy effect. The polyphenolic compounds from extras were also used to reacting with α-amylase and α-glucosidase. The result showed that quercetin had better inhibition activity of α-amylase, and ellagic acid showed better inhibition activity in α-glucosidase; while the combinations of two polyphenolic compounds in the inhibition of α-glucosidase tests showed that the combination rutin with quercetin did not have synergy effect, but others exhibited synergy effect or additive effect. However, the combinations of more than three extracts did not present synergy effect or additive effect. The rest combinations of polyphenolic compounds did not show any significant synergy effect expect the combination (+)-catechin with (-)-epicatechin in the inhibitory activity of α-amylase. These polyphenolic compounds could retard the occurrence of glycation and effectively inhibit end-products formation by inhibiting Amadori products and intermediate products which were produced in the glycation reaction. In conclusion, it could be confirmed that the guava leaf extracts had good antioxidative and the inhibory activity of α-amylase and α-glucosidase. Furthermore it could retard the occurrence of glycation reaction. The author expects guava leaf extract could be applied as a functional food to diabetes.
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Shih, Po-Hao, and 施柏豪. "Studies on α-glucosidase inhibitors and antibacterial materials produced by Paenibacillus sp. TKU037." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/jxrwkt.
Full textAbstract:
碩士淡江大學
化學學系碩士班
104
Bacterial strain TKU037 produced α-glucosidase inhibitors and antibacterial materials when cultured in nutrient broth (NB). Strain TKU037 was isolated from Taiwanese soils and identified as Paenibacillus species. Optimum culture condition for the production of α-glucosidase inhibitors and the pH and thermal stability of the produced inhibitors have been studied. A compound (1-methylhydantoin) with α-glucosidase inhibitor activity has been isolated from the culture supernatant.
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Chu, Yung-Hung, and 朱涌弘. "Purification and Characterization of α-Glucosidase and Xanthine Oxidase Inhibitors from Rhodiola Crenulata." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/99501828733426495264.
Full textAbstract:
碩士輔仁大學
食品科學系碩士班
101
Rhodiola crenulata (R. crenulata) is mainly distributed in the high cold region of Yunnan and Sichuan province. In the current study, many researches investigated that R. crenulata water extracts have the inhibitory activities to α-glucosidase. α-Glucosidase inhibitor can use to control postprandial hyperglycemia therapy for type 2 diabetes. In addition, R. crenulata water extracts have xanthine oxidase (XO) inhibitory activities. XO inhibitors have potency to block the synthesis of uric acid and use for gout treatment. The purpose of this study is to extract and purify components which have inhibitory activities to α-glucosidase and XO from R. crenulata. By using the fractionation technique and inhibitory activity assay, the seven pure compounds were isolated from water extract of R. crenulata. Those were identified by the mass spectrometer and nuclear magnetic resonance spectroscopy as salidroside, p-tyrosol, 4'-hydroxy- acetophenone, epicatechin (EC), epicatechin gallate (ECG), 2-(4-hydroxyphenyl)ethyl 3,4,5-trihydroxybenzoate (HETB) and epicatechin-(4β,8)-epicatechin gallate (B2-3’-O-gallate). Among them, B2-3’-O-gallate (IC50 = 0.31 μM), ECG (IC50 = 0.71 μM), HETB (IC50 = 4.77 μM), and EC (IC50 = 29.85 μM) have great inhibitory activities for α-glucosidase. B2-3’-O-gallate, ECG, and EC are mixed-competitive inhibitiors, while HETB is competitive inhibitor. Besides, 4'-hydroxy- acetophenone (IC50 = 15.62 μM) and B2-3’-O-gallate (IC50 = 24.24 μM) have great inhibitory activities for XO. Both B2-3’-O-gallate and 4'-hydroxyacetophenone are mixed-competitive inhibitors. Therefore, the results suggested that R. crenulata phytochemicals can be used in treatments of gout and type 2 diabetes.
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Chiang, Yi-Chen, and 江怡晨. "Characteristics of common bean seed extracts and their inhibitory activities against aldose reductase, α-amylase, and α-glucosidase in vitro." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/umvjeh.
Full textAbstract:
碩士國立中興大學
農藝學系所
101
Common bean (Phaseolus vulgaris L.) contain many polyphenolics compounds and and α-amylase inhibitor 1 (α-AI1). These bioactive compounds can be used to regulate the carbohydrate metabolism, slow down the intake of sugars and thus reduce the risks of diabetes mellitus and related diabetic complications. In this study, the polyphenolics andα-AI1s were extracted from the seeds of NaN3-induced mutant SA-05 and its wild type Hwachia by using various solvents. The chemical contents and the inhibitory activities of prepared extracts against α-amylase, α-glucosidase and aldose reductase, which were involved in carbohydrate metabolism, were examined. The result indicated that the mutant SA-05 produced higher extraction yield and extracted more bioactive compounds that Hwachia. Both the 50%- ethanol and 80%-methanol polyphenolics rich extracts prepared from mutant SA-05 and Hwachia had potent inhibitory abilities against aldose reductase and α-glucosidase with estimated IC50 values ranged between 1.32 ~ 1.94 and 0.36 ~ 0.46 mg dry mass weight ml-1, respectively. The 50%-ethanol polyphenolics rich extract also demonstrated inhibitory activity against α-amylase activity. The α-AI1 rich extracts prepared from the seeds of mutant SA-05 exhibited higher inhibitor activity against α-amylase than the extract prepared form the seeds of Hwachia. The estimated IC50 values for SA-05 ranged between s 17.68 ~ 31.11 μg dry mass weight ml-1. Thus, an initial 50%-ethanol extraction followed with a subsequent H2O extraction appears to be an appropriate choice for producing polyphenolics-rich extracts and α-amylase inhibitor-rich extracts because this way increased production of polyphenol and reduced costs. However, mutant SA-05 produced more proteinaceous α-amylase inhibitor with higher level of inhibitory activity than variety Hwachia. Therefore, mutant SA-05 is a desirable choice for producing anti-hyperglycemic compounds.
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Wang, Chia-Hui, and 王佳慧. "Inhibition of α-Glucosidase and Purification of Bioactive Substances from Hydrolysate of Chlorella pyrenoidosa." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/43910424470750739379.
Full textAbstract:
碩士國立臺灣海洋大學
食品科學系
96
The inhibitory effects of Chlorella hydrolysates (hydrolyzed by cellulase and protease) against α-glucosidase were investigated and the physiological effect on regulation of blood sugar was also evaluated. The carbohydrate, soluble protein and peptide content of three Chlorella hydrolysates (pulverized cell, unpulverized cell and residue) were increased as cellulase was added to 5%. The hydrolysate (pulverized cell) showed the highest yield being 21.40%, and α-glucosidase IC50 was 27.48 mg/mL. The hydrolysate (pulverized cell) was separated into three fractions by size exclusion chromatography on a Sephadex-50 column. The third fraction of the hydrolysate showed the lowest α-glucosidase IC50 being 0.103 mg carbohydrate/mL and 0.038 mg peptide/mL (the drug of Acarbose was 0.394 mg/mL). The yield of hydrolysates increased to 41.02 (pulverized cell), 45.78 (unpulverized cell) and 32.01% (residue), respectively, as by 5% Cellulase AP3 and 2% Protease N hydrolyzed. Then, the hydrolysate (pulverized cell) was separated into three fractions by size exclusion chromatography on a Sephadex-15 column. The third fraction of the hydrolysate showed the lowest α-glucosidase IC50 being 0.074 mg carbohydrate/mL and 0.099 mg peptide/mL. The third fraction was further analyzed by HPLC, only peak Ⅲ-1 had inhibitory effect on α-glucosidase and inhibitory efficiency ratio (IER) was 2531.8 %/mg/mL.
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Lin, Jia-Wen, and 林佳雯. "Anti-hyperglycemia activity of Galla chinensis based on the inhibition of α- glucosidase activity." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/46143593918166268087.
Full textAbstract:
碩士臺灣大學
食品科技研究所
98
Diabetes mellitus (DM) is a common metabolism disease worldwide. DM is also on the top five list of the ten major causes of death in Taiwan for many years. Hyperglycemia is the main symptom to the DM patients. It obten inducesvarious complications, and postprandial hyperglycemia is the principal factor of DM complications. Among many kinds of diabetic medicines, only α-glucosidase inhibitors can significantly lower postprandial blood glucose. This research used α-glucosidase inhibition assay to find the plant materials which has ability to inhibit α-glucosidase. It was found that among the eleven plant materials tested, Galla chinensis has the most potent inhibition activity. Therefor, we futher investigated the active component in Galla chinensis usingα-glucosidase inhibition assay. Various solvents were used to prepare Galla chinensis extracts, and ethyl acetate extract (EA) of Galla chinensis was found to have the highest ability to inhibit α-glucosidase, and it’s also had the highest activity in the DPP-4 inhibition assay, advanced glycation end products inhibition assay and α-amylase inhibition assay. We futher used Sephadex LH-20 gel to separate that EA-A ~ EA-I fractions from the Galla chinensis ethyl acetate extract, and found EA-G had the best ability to inhibit α-glucosidase among the nine fractions, the inhibition ratio of yeast α-glucosidase and rat α-glucosidase were 93.59 % and 42.91 %, respectively. The EA-G fraction also had well activity in the DPP-4 inhibition assay, DPPH free radical scavenge assay, advanced glycation end products inhibition assay and α-amylase inhibition assay, and it also increased glucose uptake of insulin resistant cells. According to the above experimental result, the EA-G fraction was futher purified using High Performance Liquid Chromatography and G1~ G7 fractions were obtained. The G4 and G5 fractions were found to have highest α-glucosidase inhibition activity among the seven fractions. These two fractions were futher analyzed by Mass Spectrometry, and found that they are 1, 2, 3, 6-tetra-O-galloyl-β-d-glucose and 1, 2, 3, 4, 6-penta-O-galloyl-β-d-glucose. This research has proved that Galla chinensis not only has high α-glucosidase inhibition activity, but also can inhibit DPP-4, scavenge free radicals, inhibit advanced glycation end products formation, inhibit α-amylase activity, and increase glucose uptake of insulin resistant cells. So, Galla chinensis can modulate blood sugar through various ways and has potential to be developed as an anti-diabetes product.
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Faridmoayer, Amirreza. "Purification and characterization of the soluble form of processing α-glucosidase I from saccharomyces cerevisiae." Thesis, 2005. http://hdl.handle.net/2429/18539.
Full textAbstract:
Saccharomyces cerevisiae processing a-glucosidase I (Cwh41p) is a type II
membrane-bound glycoprotein encoded by CWH41. This enzyme regulates the first
trimming step in the A-glycosylation pathway and may play an important role in glycoprotein
biosynthesis and quality control in the endoplasmic reticulum (ER). Despite its importance,
there is a limited understanding of the structure, functional residues, and mechanism of aglucosidase
I. Therefore this thesis was focused on establishing a robust purification method
for the soluble form of yeast a-glucosidase I, identifying the catalytic domain, and
determining structural or functional amino acid residues.
The soluble form of a-glucosidase I was purified to 95% homogeneity using a
combination of ammonium sulfate precipitation, anion-exchange, lectin affinity, and sizeexclusion
chromatographies. The molecular mass of soluble a-glucosidase I was 98 kDa by
SDS-PAGE. The purification method was improved by cultivation of transformed yeast in a
fermenter and using a deoxynojirimycin (DNM)-based column. This method reproducibly
yielded 40 pg of pure enzyme per gram of wet biomass with no detectable contamination by
other aryl a- and P-glucosidases. Cleavage between Ala24 and Thr25 of the transmembrane
domain of Cwh41p released the soluble activity and this fragment was shown to be
glycosylated.
A luminal 37 kDa non-glycosylated polypeptide was isolated as the smallest active
fragment from endogenous and trypsin hydrolysis of the soluble a-glucosidase I, using
DNM-based resins. The hydrolysis sites were determined to be between Arg521 and Thr522
for endogenous proteolysis and Lys524 and Phe525 for the trypsin hydrolysis. This 37 kDa
polypeptide was 1.9 times more active than the 98 kDa protein when assayed with the
synthetic trisaccharide.
Site-specific chemical modification of the soluble a-glucosidase I from yeast using
diethylpyrocarbonate, tetranitromethane and 3-(3-(dimethylamino)propyl)carbodiimide
revealed that histidine, tyrosine and carboxylic acid residues are involved in a-glucosidase I
activity, as these residues could be protected from modification using the competitive
inhibitor DNM. DNM could not prevent inactivation of enzyme treated with N -
bromosuccinimide used to modify tryptophan residues.
Functional expression of truncated forms of Cwh41p was also investigated. Only
Cwhtlp (E35- F833) was expressed as a catalytically active soluble fragment. Cwhtlp was
isolated as a 94 kDa non-glycosylated polypeptide with a specific activity (3600 U/mg of
protein) comparable to the soluble a-glucosidase I (3000 U/mg of protein). These results
suggest that the Ml-128 region, containing the predicted N-terminal cytosolic segment and
transmembrane domain, of Cwh41p likely carries an ER-targeting signal sequence and is not
important for protein folding.
Alignment of orthologs indicated that six highly conserved carboxylic acid residues
resided within the putative catalytic region of yeast a-glucosidase I. Substitution with A la
for E580 and D584 of Cwhtlp (E613 and D617 of Cwh41p), that are situated at the
corresponding proposed binding motif of the mammalian enzyme, resulted in undetectable aglucosidase
I activity. Furthermore, mutants were expressed at considerably lower
concentrations than Cwhtlp. These findings suggest that conserved E613 and D617 may
play an important functional or structural role in enzyme activity.
In conclusion, results of this thesis indicated that the soluble a-glucosidase I is a
proteolytic product of Cwh41p and can be functionally expressed without undergoing Nglycosylation.
Moreover, the catalytically active fragment (F525-F833) can be isolated from
the soluble a-glucosidase I but it can not be expressed alone suggesting an integral structural
function for the non-catalytic region (E53-F525). Also, chemical modification results
suggest that the potential binding residues are more conserved between yeast and plant,
rather than yeast and mammalian a-glucosidase I. Finally, the conserved E613 and D617
may play an important role in yeast a-glucosidase I activity.Land and Food Systems, Faculty of
Graduate
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Chen, Meng-Yang, and 陳孟揚. "Antioxidative Activity and Inhibitory Activities of α-Amylase and α-Glucosidase of Extracts from Defatted Black Sesame Meals fermented by Antrodia camphorata." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/cwc3wr.
Full textAbstract:
碩士國立虎尾科技大學
生物科技研究所
101
The lignans (sesamin, sesamolin, sesaminol, and sesaminol triglycoside) contents, antioxidative activities, and α-amylase (AA) and α-glucosidase (AG) inhibitory activities of water and 70% ethanol extracts (defined as WEts and EEts, respectively) from defatted black sesame meals (DBSMs) fermented by Antrodia camphorata in submerged cultivation were investigated in this study. The addition of DBSMs (0、1、2、10、20g/100ml) on lignan contents and the activities of all the extracts was also studied. The results indicated the antioxidative activities of the extracts from the fermented DBSMs (defined as fmedDBSMs) were generally better than those from the unfermented ones (defined as unfmDBSMs) when the addition concentration of DBSMs was not more than 10g/100ml, while there was no significant difference between those of fmedDBSMs and unfmDBSMs as 20g/100ml of DBSMs was added. After fermentation, A. camphorata almost contributed to the antioxidative activities of the extracts of DBSMs. The sesamin and sesamolin contents of EEts increased as the increase of DBSMs addition. These contents of EEts from fmedDBSMs were higher than those from unfmDBSMs, but only the sesamin content of EEts from fmedDBSMs for 20g/100ml of DBSMs addition was lower than that of those from unfmDBSMs. This may be due to a little of amount of sesamin degradation caused by a lot of DBSMs. In addition, the bioconversion percents of sesaminol triglycoside of EEts and WEts to sesaminol for 10g/100ml DBSMs addition were 84% and 89%, respectively. These were higher than those for the other addition concentrations of DBSMs. The inhibitory activities of AA and AG (defined as AAi and AGi, respectively) increased as the increase of DBSMs addition. The AAi and AGi of the extracts from fmedDBSMs were higher than those from unfmDBSMs. Particularly for 10g/100ml and 20g/100ml of DBSMs addition, the AAi percents of not only EEts from fmedDBSMs were higher up 61% and 75%, respectively, than those for 0g/100ml of DBSMs addition, but also those of Wets from fmedDBSMs were higher up 66% and 68%, respectively, than those without DBSMs addition. Moreover, the AGi percents of WEts from fmedDBSMs were higher up 82% and 90%, respectively, than those for 0g/100ml of DBSMs addition. However, the AGi analysis of EEts from fmedDBSMs and unfmDBSMs could not be carried out due to AG degradation caused by high alcohol content of EEts.
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奥山, 正幸. "Schizosaccharomyces pombe α-Glucosidase の構造と機能に関する研究." Doctoral thesis, 2001. http://hdl.handle.net/2115/32797.
Full text
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LIN, CHIA-YING, and 林佳瑩. "Screening the most efficiency fractions of antioxidant activity and inhibition of α-glucosidase from rice husk." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/ypdahj.
Full textAbstract:
碩士國立宜蘭大學
食品科學系碩士班
105
Diabetes is a chronic metabolic disease in modern society. Taking α-glucosidase inhibitors can ameliorate hyperglycemia in diabetic patients. Previous studies have demonstrated that ethanol extracts of rice husk(RH-E) have the antioxidant capacity and the inhibitory effect to α-glucosidase. Therefore, the objective of this study was to screen the effective fractions via silica gel column chromatography from RH-E. The RH-E have used ethyl acetate and water partition into 3 fractions, there were RH-E-EA, RH-E-H2O and precipitation RH-E-p. RH-E-E-p showed the highest inhibition of α-glucosidase and the antioxidant capacity which inhibition was 89.8% at 100 μg/mL, DPPH scavenging ability equivalent to 128.6 μmol trolox /g DW, ABTS scavenging ability equivalent to 642.1 μmol trolox /g DW and FRAP(ferric iron reducing antioxidant power) equivalent to 294.7 μmol ascorbic acid/g DW, respectively. Furthermore, RH-E-E-p was separated by silica gel column chromatography and got 11 fractions (RH-E-p-1~11). RH-E-E-p-6 showed the highest inhibition of α-glucosidase. The inhibition was 95.4% at 100 μg/mL and DPPH scavenging ability equivalent to 164.0 μmol trolox/g DW, ABTS scavenging ability equivalent to 1099.4 μmol trolox/g DW and FRAP equivalent to 305.2 μmol ascorbic acid/g DW, respectively. Continuously, RH-E-E-p-6 was separated by silica gel column chromatography and obtained 7 fractions (RH-E-p-6-I~VII). Among fractions, RH-E-E-p-6-V showed the highest inhibition of α-glucosidase. The inhibition was 40.2% at 5 μg/mL, and no significant difference with myricetin. The inhibition of α-amylase was 23.2% at 500 μg/mL, DPPH scavenging ability equivalent to 155.8 μmol trolox/g DW, ABTS scavenging ability equivalent to 1094.8 μmol trolox/g DW and FRAP equivalent to 243.8 μmol ascorbic acid/g DW, respectively. RH-Ep-6-V was analyzed by TLC and UPLC. It was found that the maximum absorption wavelength of RH-Ep-6-V was 281.6 nm and 324.5 nm, presumably may be the flavanones compounds. Above aforementioned, the best inhibition of α-glucosidase is RH-E-p-6-V which also could inhibit α-amylase and have the antioxidant ability. The main active ingredients in RH-E-p-6-V may flavanones similar to the structure of myricetin.
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Lin, Chien-Hung, and 林建宏. "THE STUDIES ON THE IMMOBILIZATION OF α—GLUCOSIDASE BY USING A pH REVERSIBLY SOLUBLE-INSOLUBLE CARRIER." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/62636499441034592453.
Full textAbstract:
碩士大同大學
生物工程研究所
88
ABSTRACT Hydroxylpropyl methylcellulose acetate succinate AS-LF type ( AS-L ), a enteric coating material which is reversibly soluble-insoluble depending on the pH condition, was used to immobilize α-glucosidase for the production of isomaltooligo-saccharides ( IMOs ). At pH value above 5.0, it is soluble so that the immobilized α-glucosidase acts like free enzyme, while at pH value below 4.2 it is precipitated, thus could be recovered and reused. Each gram of AS-LF is able to immobilize 15.5 mg of protein and 10,500 units of glucosyltranslating activity. Both free and immobilized α-glucosidase have same apparent enzyme activity at pH 5.0. They are fairly stable between pH 4 and 7, but the immobilized α-glucosidase is more heat resistant than free enzyme at 60, 70 or 80℃. The α-glucosidase is most active between pH 3 and 5. However, after immobilized, the optimum active pH becomes sharp around pH 5. High dose of immobilized α-glucosidase are applied to produce IMOs at 40, 45, 50, or 55℃ respectively. Under five repeated reactions, the final enzyme recovery at 40, 45, 50, or 55℃ are 86, 82, 77, or 60%, respectively. Thus, a short time and low temperature reaction system, i.e. in 4 hours and at 40℃, is established to produce IMOs by using such immobilized α-glucosidase. This short time and low temperature reaction model is much more effective than the traditional process which take more than 20 hours to complete the reaction. The final product contains 191 g/L of total oligosaccharides.
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KUO, YU-LING, and 郭育伶. "Preparation and characterization of zein-curcumin analogue nanoparticles with α-glucosidase and xanthine oxidase inhibitory activities." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/7kg9yk.
Full textAbstract:
碩士輔仁大學
食品科學系碩士班
107
Curcumin (CM) is a natural lipophilic polyphenol with a variety of pharmacological properties, that provide antioxidizing, antiinflammatory, antimicrobial, antiviral, antirheumatic, anticancer, and neuroprotective effects. However, curcumin is limited in terms of water-solubility, and curcumin analogues as well. Researchers have recently begun using biopolymers to encapsulate hydrophobic compounds in order to improve their bioavailability. The objective of this study was to evaluate the feasibility of using zein nanoparticles as an oral delivery vehicle for curcumin and its analogues. The investigation centered on the radical scavenging activities of ABTS and DPPH as well as the inhibition of α-glucosidase and xanthine oxidase by curcumin and its analogues, including CM-1, CM-2, CM-A, CM-F, and tetrahydrocurcumin. Fourier transform infrared spectroscopy was used to identify and characterize zein-curcumin analogues nanoparticles. All of the analogues except CM-1 presented ABTS radical scavenging activity on par with or superior to that of vitamin E. The α-glucosidase inhibitory activity of the compounds in this study was as follows: CM-F > CM > CM-A > CM-1. The α-glucosidase inhibitory effects of curcumin and its analogues were superior to those of quercetin. Furthermore, only CM-F had a good xanthine oxidase inhibitory activity (IC50 = 2.05 ± 0.15 μM), suggesting a better inhibition than that of allopurinol (IC50 = 12.04 ± 1.54 μM). Amide I, amide II and amide III of zein were observed in the nanoparticles with the peak positions either existed or slightly shifted. The main peaks of all compounds themselves were also occurred or shifted in nanoparticles, indicating that partial hydrogen bonds occurred between the hydrophobic region of zein and compounds. The resulting nanoparticles without surfactant were spherical, small (mean particle size ≈ 125-150 nm), and had a narrow size distribution (polydispersity index < 0.4). Additionally, the encapsulated compounds were in an amorphous as detected by differential scanning calorimetry. These results demonstrate that zein can indeed be used as a carrier of curcumin and its analogues. Especially, zein-CM-F nanoparticle is the most potential inhibitors using in the treatment of gout and diabetes.
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Guo, Nai-Jung, and 郭乃榕. "Effect of extracts from different plant leaves on inhibition of α-glucosidase activity and type 2 diabetes." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/49244006566876650398.
Full textAbstract:
碩士國立屏東科技大學
食品科學系所
101
Diabetes is one of the top 10 leading causes of death in Taiwan. Diabetic patients produce more free radicals during a long-term of high blood sugar than normal persons. It raises the incidence of complications. The extracts of natural plants can inhibit starch degrading enzymes, including α-glucosidase and α-amylase activity then reduce the rise of postprandial blood glucose concentration and the side effects of medicine. Alpha-glucosidase inhibitors (AGIs) is one of clinical drug used for the treatment of type 2 diabetes. Inhibition of α-glucosidase is effective to reduce postprandial blood glucose content. The objective of this study was to evaluate inhibitory effect of mixture of extract leaves of Psidium guajava L., Morus alba L. and Cinnamomoum osmophloeum K. on α-glucosidase activity and the safty of mixture extracts by cytotoxicity assay. In vitro, the IC50 values of inhibition of α-glucosidase and α-amylase activity from mixture of extracts were 0.4 mg/mL and 2.18 mg/mL, respectively. Whereas, the IC50 of the commercial anti-hyperglyhyperglycemic agent (Glucobay) were 0.24 mg/mL and 0.02 mg/mL, respectively. In cytotoxicity test, murine embryonic liver cell line mg/mL (BNL CL.2) were treated with mixed extract for 24, 48 and 72 hours. The survival percentages were no significant effects. In vivo, after feeding 4 weeks with high dosage of mixed extract, the fasting blood glucose, 2 h postprandial blood glucose and oral glucose tolerance test after 150 mins were decreased 9.15%, 2.96% and 11.69%, respectively. Besides, the mixture of plant extract can decrease the concentration of glutamic-oxalocetic transaminase (AST) and glutamic-pyruvic transaminase (ALT) in plasma, the situation of glomerular treated in various concentration of mixed extract were better than commercial anti-hyperglycemic agent.
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OH, JUNGBAE. "Evaluation of Berry Extracts on Intestinal Digestive Enzymes and Sugar Transporters." 2017. https://scholarworks.umass.edu/masters_theses_2/523.
Full textAbstract:
T2DM is a chronic disease characterized by postprandial hyperglycemia. One of the therapeutic approaches to attenuate hyperglycemia is to inhibit intestinal ɑ-glucosidase enzyme and/or suppress glucose transporters that regulate intestinal glucose transporters such as SGLT1 & GLUT2. Berries rich in polyphenol antioxidants have various health benefits. Although the antidiabetic effects of various berry extracts or berry mixture in pre-clinical and clinical studies, the underlying pathways at the molecular level is still unclear. In this study, we investigated antioxidant and antidiabetic effects of selected berry extracts by determining free radical scavenging activates, Caco-2 intestinal ɑ-glucosidase activity, glucose uptake and the gene expression of ɑ-glucosidase and glucose transporters in Caco-2 cells. Total phenolic contents of berry extracts varied from 28.55 ± 0.06 to 56.15 ± 1.08 gallic acid equivalent (GAE μg/mL) and correlated with antioxidant capacities. Both cranberry extract (CBE) and blackberry extract (BBE) at 200 μg/mL concentration significantly decreased glucose uptake in Caco-2 cells. While mRNA expression and activity of ɑ-glucosidase were inhibited by CBE and BBE, mRNA expression of SGLT1 and GLUT2 was only inhibited by CBE. Moreover, CBE and BBE significantly decreased glucose uptake in the presence of sucrose and AS. Our data suggest that CBE and BBE have different molecular mechanisms in suppressing hyperglycemia and their effects are mediated by inhibiting carbohydrate digestion and absorption.
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Chen, Chung-Chia, and 陳重嘉. "High efficiency of screening α-glucosidase inhibitor from Chinese Herbal medicines using After Flowing Through Immobilized Receptor (AFTIR)." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/83136741930399348246.
Full textAbstract:
碩士中國醫藥大學
中國醫學研究所碩士班
96
The number of diabetes patients is growing fast all over the world. Previous reports showed that lowering blood glucose levels may delay the occurrence of diabetes. Western medicines in clinical treatment of diabetes use oral hypoglycemic agents include α-glucosidase inhibitors which can effectively reduce postprandial blood glucose levels. In this study, AFTIR technology via the immobilization of α-glucosidase on chip was used to find several effective herbal extracts and has been verified as an effective method via finding the epicatechin gallate from green tea. Furthermore, the results show that Taxus blocks epigallocatechin gallate and α-glucosidase with blocking ratio of 35.9% and the activity of inhibiting α-glucosidase is significant. With the observations above, Taxus can therefore be a potential agent used for curing the diabetes patients in the future.
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Lin, Yushan, and 林鈺珊. "Studies on the Antioxidative Effect and Inhibition of α-Glucosidase Activity During Psidium guajava L. Tea Developing Procession." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/27835939791422092352.
Full textAbstract:
碩士國立宜蘭大學
食品科學系碩士班
99
Psidium guajava L. is one kind of Myrtaceae plant, which leaves and fruit with the reducing blood sugar, antioxidant have been demonstrated. In this research we used red guava (RG) harvested from Yilan County Yuanshan as raw materials. This study aims were to evaluate the antioxidant activities, inhibition of α-glucosidase activity and ascorbic acid, total phenols, total isoflavoids content of RG leaves, immature fruit, ripe fruit and its peel, sarcocarp and ascus by 40℃, 60℃ hot-air and freeze dry treatment. And then the best of treatment and RG parts with antioxidative or inhibition α-glucosidase activity was carried out the best mixing ratio for the RG tea, Further confirming optimal formulation parameters of red guava tea by the sensory evaluation. The result showed that 40℃ hot-air dry was the best drying treatment for RG. The best of RG parts with antioxidative activity and physiological composition content were leaf and immature fruit. Scavenging DPPH free radical and chelating Fe2+ ion effect are 41.41, 43.92% and 80.37, 81.98% respectively. Total phenols and flavonoids contents are 270.39, 130.58 mg/100g and 79.02, 19.88 mg/100g respectively. The best of RG parts with inhibition α-glucosidase activity were leaf and ripe fruit, the inhibition are 17.92 and 16.33% respectively. Whether as antioxidative, inhibition α-glucosidase activity or physiological composition content, the peel, sarcocarp and ascus were not significantly higher than the whole ripe fruit. The best of RG tea ratio with physiological composition content, antioxidative and α-glucosidase activity was leaf and immature fruit or leaf and ripe fruit 4:1(w/w), whereas the best of RG tea ratio with sensory evaluation was leaf and immature fruit or leaf and ripe fruit 3:2(w/w).
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WONG, YUNN-HUI, and 黃韻慧. "Antioxidative activity and inhibition of α-glucosidase (key enzyme linked to diabetes) by pomelo (Citrus grandis) peel extracts." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/75bzf7.
Full textAbstract:
碩士中國文化大學
生物科技研究所
106
Pomelo（Citrus grandis）is a native fruit of great economic importance in Southeast Asia . The peels of pomelo account for 30% of the fruit weight but they has been dumped without knowing their contribution in nutrition values . The aim of the study was to determine the hypoglycemic potential and antioxidation activities of citrus grandis whole peel, mesocarp and exocarp. Pomelo peels (whole peels, mesocarp, and exocarp) were extracted with hot water or 80% ethanol. Among the six examined samples, 80% ethanol extracted, exocarp showed the best results in terms of hypoglycemic effect and antioxidation activity. It was characterized by IC50 value of 25.12 mg/mL for α- glucosidase inhibitor , total phenolic compound ( TPC ) : 79.73 mg GAE / g sample, reducing power : 261.37 mg Vit.C/g sample, DPPH free radical scavenging rate IC50 : 8.82 mg/mL and ABTS free radical scavenging rate IC50 : 0.59 mg/mL . A high correlation was observed between total phenolic contents and anti -α-glucosidase activity. The obtained result suggest a potential use of pomelo peels as valuables source for the development of functional food or nutraceutical product.
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Hsieh, Hsin-Jung, and 謝欣容. "Effect of Heat Processing on the Activity of Bitter Melon (Momordica charantia) for Inhibiting α-glucosidase and Oxidation." Thesis, 2019. http://ndltd.ncl.edu.tw/cgi-bin/gs32/gsweb.cgi/login?o=dnclcdr&s=id=%22107NCHU5253037%22.&searchmode=basic.
Full text
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Da, Costa Mousinho Nuno Miguel Holmes. "In vitro assessment of the anti-diabetic activity of Sclerocarya birrea and Ziziphus mucronata." Diss., 2013. http://hdl.handle.net/2263/33337.
Full textAbstract:
Diabetes mellitus is a growing threat to human health. Current pharmacological agents cause undesirable side-effects. Herbal remedies offer the potential for alternative treatment strategies that may prove more cost-effective and devoid of the undesirable side-effects. The purpose of this study was to evaluate the in vitro anti-diabetic activity of aqueous and methanol extracts of Sclerocarya birrea (A. Rich.) Hochst. (Anacardiaceae) and Ziziphus mucronata Willd. (Rhamnaceae), which are traditionally used for the treatment of diabetes mellitus in southern Africa.
Polyphenolic contents of extracts were quantified using the aluminium trichloride and Folin-Ciocalteau methods. The capacity of individual extracts to scavenge both the 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) and 2,2-diphenyl-1-picrylhydrazyl radicals was used as a measure of antioxidant activity. The inhibitory activities of the crude extracts of both plants on the enzymes, α-amylase and α-glucosidase, were determined using colorimetric assays. The effects of the crude extracts on cell viability was assessed in C2C12 myotubes, HepG2 hepatocarcinoma cells, 3T3-L1 adipocytes and RIN-m5F pancreatic β-islet cells, using the Sulforhodamine B assay. Fluorescence detection was used to investigate the effects of the crude extracts on glucose uptake in C2C12, HepG2 and 3T3-L1 cells. Insulin secretion was assessed in RIN-m5F cells, using ELISA.
Crude extracts of both plants contained flavonoids and phenols, but flavonoid content was predominantly higher. All the extracts displayed antioxidant activity, with the methanol extract of S. birrea possessing the most potent free radical scavenging ability (IC50 = 2.16 μg/ml). Aqueous and methanol extracts of S. birrea displayed significantly (p < 0.05) greater inhibition of α-amylase, than the positive control, acarbose. Only the methanol extract of Z. mucronata inhibited α-amylase activity. Furthermore, crude extracts of both plants also displayed potent α-glucosidase inhibitory activity. Most of the crude extracts had low toxicity, where concentrations of 100 μg/ml of crude extract of the plants did not induce 50% cell death.
iv
Although no significant increase in insulin secretion from cultured RIN-m5F cells was noted, the crude extracts of both plants significantly (p < 0.05) increased glucose uptake in C2C12, HepG2 and 3T3-L1 cells, with efficacy significantly (p < 0.05) higher than the positive control, insulin.
From the results, the plant extracts appear to exert their hypoglycaemic effects independently of insulin, via an extra-pancreatic mechanism, possibly involving interactions with the different receptors. An additive hypoglycaemic effect originates from the inhibition of both α-amylase and α-glucosidase. The findings of the present study provide evidence that S. birrea and Z. mucronata possess in vitro anti-diabetic activity. Further investigations are required to elucidate the mechanism(s) of action of the crude extracts using more targeted in vitro assays.Dissertation (MSc)--University of Pretoria, 2013.
gm2014
Pharmacology
unrestricted
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Lodge, Jacinta [Verfasser]. "The crystal structure of α-glucosidase [alpha-glucosidase] A, AglA, from Thermotoga maritima : the first structure of a family 4 glycosyl hydrolase defines a new glycosidase clan / von Jacinta Lodge." 2003. http://d-nb.info/97088219X/34.
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Chung, Chia-Lun, and 鍾佳倫. "Studies on the Glycoside Hydrolase, Antioxidant and α-Glucosidase Inhibitory Activities of Products from Xylaria Nigripes Fermented Solid Substrates." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/92hts5.
Full textAbstract:
碩士靜宜大學
食品營養學系
103
Xylaria nigripes was inoculated into cooked solid substrates wheat bran, soybean meal and wheat bran/soybean meal mixture, and new products were formed after the colonization of fungal mycelia. The objective of this study was to evaluate the glycoside hydrolase activities, antioxidant capacities and α-glycosidase inhibitory activities of the fermented products. The products of Xylaria-fermented substrates including wheat bran ( XFW ), soybean meal ( XFS ), wheat bran/soybean meal = 1:1 ( XFW1/S1 ) and wheat bran/soybean meal = 1:4 (XFW1/S4) were lyophilized and extracted with 0.05 M sodium citrate buffer (pH 4.0) for evaluating their glycoside hydrolase activities. The results revealed that all the products contained an endo-xylanase and a variety of exo-glycosidases including β-N-acetylhexosaminidase, α-galactosidase and β-glucosidase. The activities of the endo-xylanase of the products were in the range of 5.67-5.86 units/g sample, whereas the activities of the exo-glycosidase of the products were in the range of 1.44-3.39 units/ g sample. In addition, the products of XFW1/S1 and XFW1/S4 contained an unusual exo-β-L-fucosidase. The activities of the β-L-fucosidase of the products were in the range of 0.15-0.17 units/g sample. To evaluate the potential of Xylaria-fermented substrates being an antioxidant, scavenging activtitis toward 2,2’-azino-bis (3-ethylbenzthiazoline -6-sulphonic acid ) (ABTS) and superoxide radicals were assessed. The products of Xylaria fermented wheat bran ( XFW ) and wheat bran/ soybean meal= 4:1 ( XFW4/S1 ) were lyophilized and extracted with hot water and 95% ethanol, respectively. By comparison of the trolox equivalent antioxidant capacities ( TEAC ) of the extracts toward ABTS and superoxide radicals, the ethanol extract of XFW exhibited the highest TEAC values on ABTS and superoxide radicals. The TEAC values of the ethanol extract of XFW toward ABTS and superoxide radicals were 72.42 ± 0.76 and 205.27 ± 9.99 mg trolox/g ethanol extract, respectively. To evaluate the potential of Xylaria-fermented substrates being an anti-diabetic agent, inhibitory activity of fermented substrates on the α-glucosidase was assessed. It was found that 95 % ethanol extract of XFW4/S1 exhibited the highest inhibitory activity on the hydrolysis of p-nitrophenyl-α-glucoside. Its IC50 value was 2.36 ± 0.05 mg/mL. The inhibition kinetics was analyzed by Lineweaver-Burk plots, which revealed that the ethanol extract of XFW4/S1 was a noncompetitive inhibitor.
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Godinho, Patrícia Inês Carvalho. "C-Glycosyl flavonoids as potential anticoronavirus drugs with dual action." Master's thesis, 2021. http://hdl.handle.net/10773/33119.
Full textAbstract:
The ongoing COVID-19 pandemic, caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), has spread all over the world, causing millions of deaths, and became a major global concern. Although protective vaccines have been developed and administered, efficient antiviral agents for the prevention and treatment of SARS-CoV-2 are not yet available. Moreover, since new and deadly CoVs can emerge at any time with the potential of becoming pandemics, it is crucial the development of therapeutic agents against these potentially deadly CoVs. The scientific research and the medical challenges to save lives revealed the genetic evolution and the biochemistry of SARS-CoV-2 life cycle in comparison with other coronaviruses. The SARS-CoV-2 attacks primarily the respiratory tract, through its binding of Spike glycoprotein to angiotensin converting enzyme 2 (ACE2) of the host cell, initiating the replication and transcription of viral genome by 3CLpro. There have been developed some strategies towards SARS-CoV-2 inhibition, which target the Spike glycoprotein and 3CLpro.
In the search for anti-coronaviral drugs, researchers soon turned their heads towards glycosylated flavonoids. Glycosyl flavonoids, widespread in the plant kingdom, have received a lot of attention due to their widely recognized antioxidant, anti-inflammatory, anticarcinogenic, antidiabetic activities, and to their ability to modulate key cellular enzymes function. Recently, glycosyl flavonoids have also shown promising antiviral activity against SARS-CoV-2. Despite O-glycosyl flavonoids are by far the most common in nature, C-glycosyl flavonoids have attracted much recent interest, due to their enhanced stability to chemical and enzymatic hydrolysis.
Thus, the first aim of this work was the synthesis of new C-glycosyl flavonoids to evaluate their antiviral activity towards the SARS-CoV-2. The synthesis of C-glycosyl flavonoids was achieved through the cross-coupling Heck reaction between a 3-bromo flavonoid and a modified sugar alkene. Although the synthesis of C-glycosyl flavones was not well-succeeded, it was possible to synthesize C-glycosyl 2-styryl-4H-chromen-4-ones, although, the presence of isomers was observed.
The new synthesized compounds were unequivocally characterized by mono- (1H and 13C) and two-dimensional (HSQC, HMBC, NOESY) nuclear magnetic resonance (NMR) spectroscopy techniques. Whenever possible, they were also characterized by mass spectrometry and high-resolution mass spectrometry. Since the new synthesized C-glycosyl 2-styryl-4H-chromen-4-ones were obtained as a mixture of isomers, the evaluation of the antiviral activity could not be performed. Further studies to separate the isomers are needed, as well as the evaluation of the antiviral activity towards the 3CLpro and α-glucosidases. Furthermore, molecular docking studies will be conducted to understand the interactions of the new synthesize C-glycosyl flavonoids with SARS-CoV-2 3CLpro and the α-glucosidases.A pandemia da COVID-19 que decorre atualmente, causada pela Síndrome Respiratória Aguda Grave Coronavírus 2 (SARS-CoV-2), espalhou-se por todo o mundo, causando milhões de mortes, e tornou-se uma preocupação global. Apesar de terem sido desenvolvidas e administradas vacinas, a doença continua ativa e ainda não estão disponíveis terapêuticas antivirais eficazes para a prevenção e o tratamento da SARS-CoV-2. Além disso, uma vez que novos e potencialmente mortais coronavírus (CoVs) podem surgir a qualquer momento com o potencial de se tornarem pandémicos, é crucial o desenvolvimento de agentes terapêuticos contra estes vírus. A pesquisa científica e os desafios médicos para salvar vidas revelaram a evolução genética e a bioquímica do ciclo de vida do SARS-CoV-2 em comparação com outros coronavírus. O SARS-CoV-2 ataca principalmente o trato respiratório, por meio da sua ligação da glicoproteína Spike à enzima conversora de angiotensina 2 (ACE2) da célula hospedeira, iniciando a replicação e transcrição do genoma viral pela 3CLpro. Deste modo, têm vindo a ser desenvolvidas algumas estratégias para a inibição da SARS-CoV-2, que têm como alvo a glicoproteína Spike e a 3CLpro. Na busca por medicamentos anticoronavírus, alguns grupos de investigação têm-se focado no estudo de flavonoides glicosilados. Os glicosil flavonoides, distribuídos abundantemente pelo reino vegetal, têm recebido muita atenção devido às suas atividades antioxidantes, anti-inflamatórias, anti carcinogénicas e antidiabéticas amplamente reconhecidas, e pela sua capacidade de modular a função de enzimas celulares essenciais. Recentemente, os glicosil flavonoides também mostraram atividade antiviral promissora contra o SARS-CoV-2. Apesar de os O-glicosil flavonóides serem os mais comuns na natureza, os C-glicosil flavonoides têm atraído recentemente muito interesse, devido à sua estabilidade à hidrólise química e enzimática. Assim, o primeiro objetivo deste trabalho foi a síntese de novos C-glicosil flavonóides para avaliar sua atividade antiviral contra o SARS-CoV-2. A síntese dos C-glicosil flavonóides foi efetuada através da reação acoplamento de Heck entre um 3-bromo flavonóide e um alceno de açúcar modificado. Embora a síntese de C-glicosil flavonas não tenha sido conseguida, foi possível sintetizar C-glicosil 2-estiril-4H-cromen-4-onas, embora a reação origine uma mistura de isómeros. Os novos compostos obtidos foram caracterizados por técnicas de espectroscopia de ressonância magnética nuclear (RMN) mono- (1H e 13C) e bi-dimensionais (HSQC, HMBC, NOESY). Sempre que possível, foram também caracterizados por espectrometria de massa e espectrometria de massa de alta resolução. Visto que os novos C-glicosil 2-estiril-4H-cromen-4-onas sintetizados possuem isómeros, a avaliação da atividade antiviral não pôde ser efetuada. Mais estudos para separar os isômeros formados são necessários, bem como a avaliação da atividade antiviral frente à 3CLpro e α-glucosidases. Além disso, estudos de docking molecular serão conduzidos para entender as interações dos novos C-glicosil flavonóides sintetizados com a 3CLpro da SARS-CoV-2 e as α-glucosidases.
Mestrado em Bioquímica
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Renz, Helene [Verfasser]. "Kinetische Studien an den Leitenzymen alkalische Phosphatase, neutrale α-Glucosidase [Alpha-Glucosidase] und Na+-K+-ATPase einer renalen Bürstensaummembranfraktion von Ratten mit einem akuten oder chronischen, Streptozotocin-induzierten Diabetes / vorgelegt von Helene Renz." 2000. http://d-nb.info/965588343/34.
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Duarte, Ana Marta Cardoso. "Macroalgas para Aplicações Alimentares: Ingredientes Naturais na Prevenção da Diabetes Tipo 2." Master's thesis, 2019. http://hdl.handle.net/10400.8/4379.
Full textAbstract:
A diabetes mellitus corresponde a uma patologia caraterizada por hiperglicémia
crónica, sendo a diabetes mellitus tipo 2 (DM2) relacionada com a deterioração progressiva
das funções das células β pancreáticas. A nutrição é considerada fundamental no controlo da
DM2, com evidências crescentes dos benefícios das macroalgas, pelo seu teor de compostos
antioxidantes (ação inibitória sobre enzimas do metabolismo de glícidos) e riqueza
nutricional em macronutrientes torna-as um recurso alimentar de excelência. O presente
estudo visa a avaliação da atividade inibitória das enzimas α-amilase, α-glucosidase e
dipeptidil-peptidase-4 (DPP4) pelo extrato da macroalga Fucus spiralis, bem como a
avaliação da sua capacidade antioxidante, com posterior validação em matriz alimentar
como caso de estudo.
As condições de extração dos compostos bioativos, por vortex, banho de ultrassons,
homogeneizador e sonicador, foram otimizadas utilizando a metodologia de superfície de
resposta (MSR) usando o desenho central rotacional (CRD) com base em três variáveis
independentes (tempo de extração, biomassa e solvente), tendo como resposta: IC50 para
DPPH; μmol EAA/g para FRAP; mg EAG/g para TPC. Posteriormente, as condições ótimas
de extração selecionadas, tiveram em conta a maior extração de antioxidantes, requisitos de
sustentabilidade ambiental e segurança alimentar (ausência de solventes orgânicos, recurso
de materiais e tempo reduzido). A extração de antioxidantes otimizada foi obtida recorrendo
ao homogeneizador, com as condições de extração: solvente de 50 ml etanol/100 ml com 26
% biomassa, durante 300 segundos. O extrato otimizado revelou capacidade antioxidante,
segundo os métodos estudados (FRAP = 134,560 ± 91,738 mol EAA/g extrato; TPC =
271,310 ± 12,710 mg EAG/g extrato), bem como inibição da α-amilase (IC50 = 0,018 (0,011
– 0,028) mg/ml), α-glucosidase (IC50 = 0,0004 (5,485 x 10-7
– 0,003) mg/ml) e DPP4 (IC50
= 0,003 (0,002 – 0,004) mg/ml). O potencial de inibição enzimático, avaliado por
metodologia in vitro com métodos espectrofotométricos, revelou-se superior à acarbose,
inibidor da α-amilase e α-glucosidase, alcançando-se inibições semelhantes entre a DPP4 e
a diprotina A.
Como caso de estudo, desenvolveu-se e caracterizou-se um puré de maçã com adição
de extrato de Fucus spiralis. Os resultados demonstraram que o produto desenvolvido
revelou capacidade antioxidante (FRAP = 239,062 ± 42,651 mol EAA/g extrato; TPC =
303,880 ± 14,570 mg EAG/g extrato), bem como inibição enzimática (IC50 α-amilase =0,027 (0,023 -0,032) mg/ml; IC50 α-glucosidase = 0,020 (0,018 – 0,023) mg/ml; e IC50
mínimo de 0,010 (0,004 – 0,021) mg/ml para a DPP4).
A avaliação química do puré revelou teores de humidade >80 %, aumento do pH com
o tempo, teores de sacarose >15 g/ 100 g e índice de escurecimento, ao fim de 8 dias, superior
a 90 % nas amostras de puré e de 77 % num produto comercial semelhante, indicando
elevada atividade enzimática. Por último, o puré foi avaliado por uma painel sensorial semitreinado, verificando-se boa aceitabilidade indicando potencial do produto desenvolvido no
mercado.
Foram inquiridos 105 diabéticos tipo 2, visando a avaliação do seu perfil de consumo,
bem como a sua facilidade em interpretar rótulos alimentares permitindo conhecer a
potencialidade do puré de maçã com extrato de alga desenvolvido, como caso de estudo. A
amostragem é representada por mulheres (67,6 %, n = 71) entre os 56 e 65 anos (27,6 %, n
= 29), do distrito de Lisboa (63,8 %, n = 67), com ensino básico ou inferior (52,4 %, n = 55)
e com consumo maioritário de cereais e derivados (31,4 %, n = 33). Verificou-se que o
consumo de algas é unicamente explicado pela idade (Fisher = 13,488, p-value = 0,006) e
habilitações académicas (Fisher = 10,329, p-value = 0,005), instigando a necessidade de
desenvolvimento de estratégias de promoção dos benefícios do consumo de algas na restante
população.
O extrato de Fucus spiralis demonstrou elevada capacidade antioxidante e de inibição
de enzimas alvo na prevenção e controlo da patologia, tornando-se promissor na prevenção
da DM2.
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Lu, Shu-Wei, and 呂書瑋. "Studies on the Preparation of Water-soluble Low-molecular-weight Chitosan Derivatives and Their Free Radical Scavenging and α-glucosidase Inhibitory Activities." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/d8cvfw.
Full textAbstract:
碩士靜宜大學
食品營養學系
103
Chitosan is a non-toxic, biocompatible and biodegradable natural macromolecule, and shown to be a valuable biopolymer because of its widespread applications in biomedical, food and chemical industries. However, chitosan has several drawbacks to be utilized in biological applications, including poor solubility under physiological conditions and high viscosity. Apparently it is important to prepare water-soluble chitosans and explore their biological activities. Therefor, in this study, three kinds of water-soluble low-molecular-weight chitosan (LMWC) derivatives were prepared and their biological activities including antioxidant capacity and α-glucosidase inhibitory activity were investigated. To synthesize three different chitosan derivatives, commercial chitosan with molecular mass of 1000 kDa and 84% of deacetylation were chemically modified by grafting 2-chloroethanol, 2-chloroacetate and 2-chloroethylamine hydrochloride at C-6 position. The attached substituting branched-chain on chitosan were ethylene glycol (EG), carboxymethy (CM) and aminoethyl (AE) groups, respectively. After digested by the jelly fig latex chitosanase, the synthesized water-soluble chitosan derivatives were depolymerized and three kinds of water-soluble LMWC derivatives, namely EG-LMWC, CM-LMWC and AE-LMWC, were generated. The molecular masses of EG-LMWC, CM-LMWC and AE-LMWC were 11.2, 11.2, and 8.89 kDa, respectively, as estimated by gel filtration on Superose 12 HR column. Antioxidant activities of the prepared LMWC derivatives were evaluated with models of scavenging effects on ABTS, superoxide and oxygen radicals. By comparison of the trolox equivalent antioxidant capacities (TEAC) toward ABTS radicals, CM-LMWC showed the highest scavenging activity, followed by AE-LMWC and EG-LMWC. The TEAC value of CM-LMWC toward ABTS radicals was 45.97 ±0.1 mg trolox/ g sample. By comparison of trolox equivalent (TE) toward superoxide radicals, AE-LMWC was superior to CM-LMWC and EG-LMWC. The TE values for AE-LMWC toward superoxide radicals was 1853 ± 52 mg trolox/ g sample. By comparison of oxygen radical absorption capacities (ORAC), AE-LMWC and CM-LMWC were superior to EG-LMWC. The ORAC values of AE-LMWC and CM-LMWC were 2715 ± 113 and 1894 ± 347 μmol trolox/ g sample, respectively. To evaluate the potential of LMWC derivatives being an anti-diabetic agent, inhibitory activity of EG-LMWC and CM-LMWC on the α-glucosidase was assessed. It was found that EG-LMWC and CM-LMWC had potent inhibitory effects on the hydrolysis of p-nitrophenyl- α-glucoside by α-glucosidase. The IC50 values for EG-LMWC and CM-LMWC were 2.96 ± 0.05 and 2.65 ± 0.03 mg/mL, respectively. The inhibition kinetics were analyzed by Lineweaver-Burk plots, which revealved that EG-LMWC was a noncompetitive inhibitor whereas CM-LMWC was a mixed type inhibitor.