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Статті в журналах з теми "Quantitative determination for the biological activity using NMR"
1
Premchand, Patil Deepak V. Nagarale and Bhata R. Chaudhari*. "RECENT ADVANCES AND APPLICATIONS OF TELMISARTAN." Indo American Journal of Pharmaceutical Sciences 04, no. 10 (2017): 3935–45. https://doi.org/10.5281/zenodo.1035249.
Повний текст джерелаАнотація:
Telmisartan is pharmacologically active molecule, Here we reviewed some synthetic methods and their application like angiotensin II receptor, quantitative determination for the biological activity using NMR, restrict NFAT nuclear translocation and etc..
2
Larive, Cynthia K., Dimuthu Jayawickrama, and Laszlo Orfi. "Quantitative Analysis of Peptides with NMR Spectroscopy." Applied Spectroscopy 51, no. 10 (1997): 1531–36. http://dx.doi.org/10.1366/0003702971939055.
Повний текст джерелаАнотація:
The determination of peptide concentration with 1H nuclear magnetic resonance (NMR) spectroscopy using an internal standard or an external standard in a sealed glass capillary was investigated for three tyrosine-containing tripeptides. Trimethylsilylpropionic acid (TSP) and maleic acid were tested as external standards for quantitation by proton NMR. Although comparable results were obtained for either standard, the performance of maleic acid was found to be superior because of its better long-term stability in the sealed capillary. Loss of TSP from solution occurred over time due to adsorption onto the walls of the capillary, necessitating frequent recalibration against the primary standard, potassium acid phthalate (KHP). The peptide contents of solid peptides determined with 1H NMR are compared with those obtained from ultraviolet (UV) absorbance measurements of the tyrosine chromophore. The versatility of NMR for the quantitative analysis of peptides that do not contain an appropriate UV chromophore make it well-suited for the determination of peptide concentration in aggregation studies or for the preparation of solutions for high-throughput screening of biological activity.
3
RAKS, V. A. "INOSITOLS: BIOLOGICAL ROLE AND APPLICATION, METHODS OF EXTRACTION FROM PLANT RAW MATERIALS AND DETERMINATION, BIOTECHNOLOGICAL SYNTHESIS." Biotechnologia Acta 17, no. 3 (2024): 29–46. http://dx.doi.org/10.15407/biotech17.03.029.
Повний текст джерелаАнотація:
The aim of the work was to review modern extraction, detection and quantification analytical methods of inositols and their derivatives. Methods. Inositols are extracted from vegetable raw materials by methods of liquid extraction, under pressure, microwave extraction and supercritical fluid extraction. Quantitatively analyzed by methods of gas and liquid chromatography with preliminary derivatization. The structure of inositols can be determined by the NMR spectroscopy. Results. Inositols and their derivatives are biologically active compounds, wich are involved in the egulation of the intracellular calcium level, the transmission of hormonal signals, the breakdown of fats and the reduction of cholesterol in the blood, the modulation of the neurotransmitters activity, etc. Inositols are used in the production of vitamin preparations. The main source for inositols extraction is vegetable raw material, namely alfalfa, as well as wheat sprouts, grapefruit, hazelnuts and others. In the paper, the methods of inositols extraction with organic and inorganic solvents, including the use of a Soxhlet apparatus, liquid extraction under pressure, microwave extraction and supercritical fluid extraction are considered. The procedure of preliminary sample preparation and polyols derivatization for their further separation and quantitative determination is described. Modern chromatographic methods of polyols identification and quantitative determination are analyzed. The possibility of using 1H, 13C and 31P NMR spectroscopy to identify the structure of inositols and their derivatives is described. Conclusions. Inositols are biologically active compounds of a wide spectrum of action, therefore there is an urgent need to develop biotechnological processes for their production and extraction from plant raw materials and microorganisms.
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Rogov, A. V., and G. V. Mokrov. "Determination of the composition of pharmaceutical substances used in drugs with antiarrhythmic activity." Pharmacokinetics and Pharmacodynamics, no. 4 (January 22, 2024): 95–109. http://dx.doi.org/10.37489/2587-7836-2023-4-95-109.
Повний текст джерелаАнотація:
Cardiac arrhythmias are the most common pathologies of the cardiovascular system. Allapinin® and Allaforte® from “Pharmcenter VILAR” are effective IC-class antiarrhythmic agents. The main component of these drugs is a pharmaceutical substance with INN: lappaconitine hydrobromide, which in addition to lappaconitine hydrobromide itself, contains impurities of other diterpene alkaloids. This work is devoted to a detailed analysis of the alkaloid composition of a new pharmaceutical substance isolated from roots and rhizomes, as well as from the aerial part of plants of the genus Aconite (monkshood, wolfsbane) of the Ranunculaceae family (buttercups) using chromato-mass spectrometry and NMR spectroscopy. In addition, an assessment was made of the quantitative ratios of alkaloids in several samples of pharmaceutical substances isolated from different batches of medicinal plant raw materials.
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Satpathi, Sagar, Tamaki Endoh, Peter Podbevšek, Janez Plavec, and Naoki Sugimoto. "Transcriptome screening followed by integrated physicochemical and structural analyses for investigating RNA-mediated berberine activity." Nucleic Acids Research 49, no. 15 (2021): 8449–61. http://dx.doi.org/10.1093/nar/gkab189.
Повний текст джерелаАнотація:
Abstract Non-coding RNAs are regarded as promising targets for the discovery of innovative drugs due to their abundance in the genome and their involvement in many biological processes. Phytochemicals (PCs) are the primary source of ligand-based drugs due to their broad spectrum of biological activities. Since many PCs are heterocyclic and have chemical groups potentially involved in the interaction with nucleic acids, detailed interaction analysis between PCs and RNA is crucial to explore the effect of PCs on RNA functions. In this study, an integrated approach for investigating interactions between PCs and RNAs were demonstrated to verify the RNA-mediated PCs functions by using berberine (BRB) as a model PC. RNA screening of a transcriptome library followed by sequence refinement found minimal RNA motif consisting of a cytosine bulge with U-A and G-U neighbouring base pairs for interaction with BRB. NMR-based structure determination and physicochemical analyses using chemical analogues of BRB demonstrated the importance of electrostatic and stacking interactions for sequence selective interaction and RNA stabilization. The selective interaction with a relatively small RNA motif based on a chemical structure of a planer heterocyclic highlights the biological activities of various PCs mediated by the interactions with particular functional RNAs. In addition, the systematic and quantitative investigations demonstrated in this study could be useful for the development of therapeutic chemicals targeting functional RNAs, based on the PCs, in the future.
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Roman, Roxana, Lucia Pintilie, Miron Teodor Căproiu, et al. "New N-acyl Thiourea Derivatives: Synthesis, Standardized Quantification Method and In Vitro Evaluation of Potential Biological Activities." Antibiotics 12, no. 5 (2023): 807. http://dx.doi.org/10.3390/antibiotics12050807.
Повний текст джерелаАнотація:
New N-acyl thiourea derivatives with heterocyclic rings have been synthesized by first obtaining isothiocyanate, which further reacted with a heterocyclic amine, characterized by (FT-IR, NMR spectroscopy and FT-ICR) and tested for their in vitro antimicrobial, anti-biofilm and antioxidant activities to obtain a drug candidate in a lead-optimization process. From the tested compounds, those bearing benzothiazole (1b) and 6-methylpyridine (1d) moieties revealed anti-biofilm activity against E. coli ATCC 25922 at MBIC values of 625 µg/mL. Compound 1d exhibited the highest antioxidant capacity (~43%) in the in vitro assay using 1,1-diphenyl-2-picrylhydrazyl (DPPH). Considering the in vitro results, the highest anti-biofilm and antioxidant activities were obtained for compound 1d. Therefore, a reversed-phase high-performance liquid chromatography (RP-HPLC) method has been optimized and validated for the quantitative determination of compound 1d. The detection and quantitation limits were 0.0174 μg/mL and 0.0521 μg/mL, respectively. The R2 correlation coefficient of the LOQ and linearity curves were greater than 0.99, over the concentration range of 0.05 μg/mL–40 μg/mL. The precision and accuracy of the analytical method were within 98–102%, confirming that the method is suitable for the quantitative determination of compound 1d in routine quality control analyses. Evaluating the results, the promising potential of the new N-acyl thiourea derivatives bearing 6-methylpyridine moiety will be further investigated for developing agents with anti-biofilm and antioxidant activities.
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Ryazanova, Tatyana K., Vladimir A. Kurkin, Anna A. Shmygareva, Svetlana N. Glushchenko, and Albert I. Agapov. "The current issues of standardization of <i>Aloe arborescens</i> Mill. leaves." Aspirantskiy Vestnik Povolzhiya 21, no. 5-6 (2021): 78–86. http://dx.doi.org/10.55531/2072-2354.2021.21.3.78-86.
Повний текст джерелаАнотація:
BACKGROUND: Aloe arborescens Mill. leaves contain a whole complex of biologically active compounds (derivatives of anthraquinone, anthrone, pyrone, biopolymers, etc.) and are widely used in medical practice as raw materials for the production of anti-inflammatory, wound healing agents. The presence of anthracene derivatives in the leaves determines the laxative activity of raw plant materials and preparations. It emphasizes the importance of Aloe arborescens preparations for internal use in inflammatory diseases accompanied by constipation and decrease in secretory activity. Another biologically active compound with which the anti-inflammatory activity of aloe leaves may be associated with a pyrone derivative aloenin. At the same time, despite the widespread use in medicine and a well-studied chemical composition, the problems in the field of standardization of raw materials and preparations of Aloe arborescens are still urgent. The methods for determining the quantitative content of anthracene derivatives described in the literature are multistage, they provide for preliminary acid hydrolysis in combination with oxidation, liquid-liquid extraction of the formed aglycones and complexation with magnesium acetate. The approved regulatory documents for aloe raw materials and preparations does not provide for the assay of aloenin
 AIM: The aim is to develop the methods for determining the quantitative content of biologically active compounds in the raw materials and preparations of fresh leaves of Aloe arborescens by using the spectrophotometric method and the high-performance liquid chromatography method.
 MATERIALS AND METHODS: The objects of research were fresh leaves of Aloe arborescens Mill., and juice obtained ex tempore from fresh leaves of aloe. Samples of raw materials were collected in the summer and autumn of 2020 in the Winter Garden of the Department of Pharmacognosy with Botany and Bases of Phytotherapy at Samara State Medical University. Individual substances were isolated by column chromatography. In the study, the Bruker DRX 500 instrument (126.76 MHz) was used to determine 13C NMR spectra, and the Bruker AM 300 instrument (300 MHz) was used to determine 1H NMR spectra. Mass spectra were recorded on mass spectrometer Kratos MS-30, UV spectra were recorded by means of the spectrophotometer Specord 40 (Analytik Jena). High-performance liquid chromatography analysis was carried out with the use of the chromatograph Milichrom-6 (Nauchpribor, Russia).
 RESULTS: As a result of the study, aloenin and a mixture of aloins A and B (barbaloin) were isolated from the leaves of Aloe arborescens by with the use of column chromatography. The method for the determination of the quantitative content of aloenin by microcolumn reversed-phase high-performance liquid chromatography with UV detection (306 nm) was developed, the mobile phase was acetonitrile: 1% acetic acid solution in water in the ratio of 25:75, the elution rate is 100 L / min. The method for the quantitative determination of the total amount of anthracene derivatives in Aloe arborescens fresh leaves (differential spectrophotometry with an alkaline-ammonia solution at 412 nm) was developed. The optimal conditions for the extraction were selected. They are extractant of 40% ethyl alcohol, extraction within 60 minutes at the ratio of raw material extractant is 1:50. Validation analysis has shown that the developed methods are characterized by satisfactory metrological indicators.
 CONCLUSIONS: The obtained results can be used to update the pharmacopoeial monograph Aloe arborescens leaves fresh.
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Sobolev, R. V., I. E. Sokolov, N. A. Petrov, V. А. Sarkisyan, and A. A. Kochetkova. "Methods of extraction, separation and identification of cyclic peptides from flaxseed (Linum usitatissimum L.): A review." Food systems 7, no. 4 (2025): 535–42. https://doi.org/10.21323/2618-9771-2024-7-4-535-542.
Повний текст джерелаАнотація:
Oilseed flax (Linum usitatissimum L.) is a valuable crop characterized by a high content of fats, dietary fiber, protein and various biologically active substances, in particular cyclopeptides. Cyclic peptides are a group of cyclic hydrophobic peptides consisting of eight to ten amino acids with a molecular weight in the range of 950–2300 Da. Flax oil and seeds contain from 0.1 to 0.3% cyclopeptides, which can exhibit antioxidant, anti-inflammatory, immunosuppressive, antihypertensive and antitumor activity. The aim of this review was to systematize and summarize the available literature data on methods of extraction, separation and identification of cyclopeptides from flaxseed oil. It was found that the main methods for obtaining cyclopeptides are solid-liquid, liquid-liquid or solid-phase extraction. Commonly used solvents include methanol, hexane, ethyl acetate, dichloromethane, acetonitrile and deionized water. Preparative flash chromatography on silica gel or polymer adsorbents is used to purify and concentrate cyclopeptides, and high-performance liquid chromatography (HPLC) is used to obtain individual standards. The most commonly used stationary phases are non-polar modified sorbents — octadecyl (C18) and phenylhexyl functional groups. Identification is carried out using instrumental methods of analysis: IR spectroscopy, NMR, HPLC with a diode array detector (HPLC-PDA/DAD), high-resolution tandem mass spectrometry with electrospray ionization (ESI-HR-MS/MS). For the qualitative and quantitative determination of cyclopeptides, the HPLC with a diode array detector at a wavelength of 214 nm is sufficient. In turn, mass spectral methods, including tandem mass spectrometry, make it possible to confirm the qualitative composition and establish the amino acid sequence of cyclic peptides.
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Kotova, Elizaveta O., Alexandra Yu Moiseeva, Zhanna D. Kobalava та ін. "Proinflammatory cytokines IL-6, IL-1β, TNF-α in infective endocarditis". Terapevticheskii arkhiv 96, № 4 (2024): 342–48. http://dx.doi.org/10.26442/00403660.2024.04.202711.
Повний текст джерелаАнотація:
Aim. To study the features of macrophages in the tissues of resected valves in operated patients with infective endocarditis (IE), their significance and interaction with inflammatory markers to improve the effectiveness of IE diagnosis. Materials and methods. Prospectively the research included 25 adult patients with active IE (Duke criteria 2015) and 24 patients with heart defects without IE, hospitalized in a cardiosurgical hospital in Moscow (2021–2022). A standard laboratory and instrumental examination was carried out for the diagnosis of IE, including etiological diagnosis with microbiological and molecular biological methods, and echocardiographic examination of heart. Additionally, the neutrophil-to-lymphocyte ratio (NLR) was calculated. The study of macrophages was carried out in the tissues of resected valves with the determination of the expression of pro- and anti-inflammatory cytokine genes, macrophage markers (CD 68+) using real-time PCR. Results. Increased expression of proinflammatory cytokines IL-1β, TNF-α and IL-6 was revealed in the group of operated patients with IE with significant differences in IL-1β (CI [IQR] 0.00367 [0.00047–0.01553] vs 0.00018 [0.00012–0.00262]; p0.05) and IL-6 (CI [IQR] 0.00367 [0.00047–0.01553] vs 0.00018 [0.00012–0.00262]; p0.05) and IL-6 (CI [IQR] 0.00338 [0.00066–0.01674] vs 0.00054 [0.00044–0.00378]; p0.05). The expression of anti-inflammatory cytokines in valve tissues prevailed in the control group without significant differences from patients with IE. The macrophage marker CD 68+ was revealed in all examined patients with a significant quantitative predominance in the group of patients with IE. There were no differences in the expression of pro- and anti-inflammatory cytokines depending on the presence of embolic events, intracardiac complications, etiological affiliation to S. aureus, as well as hospital mortality and combined endpoint (death from all causes or recurrence of IE 6 months after surgery) in patients with IE with or without events. Cytokines IL-1β and IL-6 positively correlated with each other, with leukocytes and NLR. ROC analysis determined that IL-1β and NLR had the most favorable features for the diagnosis of IE [IL-1β AUC 0.816 (p=0.02), NLR AUC 0.807 (p=0.03)]. IL-6 did not show a diagnostic value in IE. The threshold value for IL-1β was 0.00029 (sensitivity 86.4%, specificity 60.0%, prognostic value of negative result 75.0% and positive 76.0%, AUC 0.761; p=0.008). Conclusion. The valve macrophages of patients with IE express elevated levels of proinflammatory cytokines IL-1β and IL-6, regardless of etiological affiliation or complicated course of IE. IL-1β has a high diagnostic value for determining the inflammatory activity in IE.
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Dijs, Ivo J., Eric van der Windt, Lauri Kaihola, and Klaas van der Borg. "Quantitative Determination by 14C Analysis of the Biological Component in Fuels." Radiocarbon 48, no. 3 (2006): 315–23. http://dx.doi.org/10.1017/s0033822200038777.
Повний текст джерелаАнотація:
Radiocarbon analysis was performed by liquid scintillation counting (LSC) and accelerator mass spectrometry (AMS) to assess whether the content of biological components in hydrocarbon fuels could be derived. Different fuel mixtures were prepared containing bioethanol, fossil ethanol, and fossil gasoline. The specific 14C activity of these mixtures was obtained from LSC measurements and directly related to the concentration of carbon originating from the bioethanol (biocarbon). The results were checked via standardized carbon dating procedures and AMS. A good linear correlation exists between the fuel mixture's specific 14C activity and the concentration of biocarbon. Also, the biocarbon fraction of the fuel mixture (the ratio biocarbon : total carbon) and the normalized fraction of biocarbon (%M) showed good linear correlation. Therefore, both relations provide a possibility to quantitatively determine a fuel's biocarbon content by 14C analysis. When the sample composition is known (e.g. resolved by gas chromatography-mass spectroscopy [GC-MS] and nuclear magnetic resonance [NMR]), the amount of particular biological components in a fuel sample can be derived subsequently. For mixtures of bioethanol, fossil ethanol, and gasoline with bioethanol contents in the range of 0.5–2% m/m, it was found that errors in the normalized fraction of biocarbon (%M) were in the range of 25–10%, respectively. For samples with a higher bioethanol content (up to pure bioethanol), the errors in %M were <10%. Errors might be larger if substantial changes in the concentration of atmospheric 14C took place during the growth period of the biofuel feedstock. By taking into account the variation in specific 14C activity of carbon over the last decades, and by modeling simple tree-growth, it could be illustrated that this effect becomes significant only if the biofuel feedstock stopped growing more than 1 decade ago, e.g. with wood from constructions.
Частини книг з теми "Quantitative determination for the biological activity using NMR"
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Wemmer, D. "Design and Characterization of New Sequence Specific DNA Ligands." In Biological NMR Spectroscopy. Oxford University Press, 1997. http://dx.doi.org/10.1093/oso/9780195094688.003.0026.
Повний текст джерелаАнотація:
During the early 1980s there were two developments which lead to our studies of sequence specific DNA ligands. The first was the development of sequential assignment methods based on 2D NMR spectra which allowed complete assignment of resonances for proteins (Wüthrich, 1986). The assignments in turn allowed determination of many structural restraints through interpretation of NOESY crosspeaks and coupling constants from COSY type spectra. The second advance was the improvement of the chemistry for direct synthesis of DNA oligomers. With multimilligram samples of DNA oligomers available sequential assignment methods for DNA, paralleling those for proteins, were also worked out. Again with assignments came the possibility of determining DNA structures in solution. Howeverfor double stranded, Watson-Crick paired DNAs the structure can be reasonably approximated by the standard B-form model derived from fiber diffraction. The accurate determination of local conformational features has been somewhat difficult using NMR since tertiary contacts (as are so valuable in determining protein structures) do not occur. However with careful quantitative analysis some of the local details of structure can be determined. These NMR methods also offered the possibility of trying to understand the structural basis for binding of ligands to DNA oligomers. In order to make welldefined complexes we wanted to start with a compound that showed some sequence specificity in binding, and selected distamycin (shown below), a polypyrrole antibiotic which was known to have preference for binding to A-T rich DNA sequences. A close relative, netropsin, had been studied by Dinshaw Patel who showed that the binding is in the minor groove by identifying an NOE between a proton of the ligand and an adenosine H2 in the center of the minor groove (Patel, 1982). We began by making a complex with the self-complementary DNA oligomer: 5'-CGCGAATTCGCG-3', which had been studied extensively by X-- ray crystallography, and also by NMR. Distamycin did form a well-defined complex with this DNA, which was is slow exchange with free DNA during titrations (Klevit et al., 1986).
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Thakur, Rajneesh, Nikhil Mehta, Ajeet Singh, Kanchan Joshi, Ankita Gautam, and Navneet Bithel. "Techniques for the Isolation of Plant-Based Bioactive Compounds." In Advances in Bioinformatics and Biomedical Engineering. IGI Global, 2022. http://dx.doi.org/10.4018/978-1-6684-7337-5.ch011.
Повний текст джерелаАнотація:
Phytochemicals are natural active ingredients that are occurring in plants. In the pursuit for novel biomolecules, the recovery of bioactive composites from plants, as well as their quantitative and qualitative evaluation, is critical. In the discovery and characterization of bioactive compounds, plant extraction and separation remain a critical concern. Analysis of bioactive compounds found in plant extracts using various approaches involving the use of chromatographic methods such as HPLC, TLC, OPLC, GC, PC, CC, and detection through FTIR, NMR, and MS is a frequent practice in the isolation of these bioactive compounds. The pure compound's structure and biological activity/bioactivity, such as antioxidant, antibacterial, or cytotoxicity, are then determined, along with their simplicity, specificity, and speed.
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Georgiou, George, and Barrett R. Harvey. "Applications of Flow Cytometry in Protein Engineering." In Flow Cytometry for Biotechnology. Oxford University Press, 2005. http://dx.doi.org/10.1093/oso/9780195183146.003.0017.
Повний текст джерелаАнотація:
In recent years, the application of evolutionary methods for protein engineering has created tremendous optimism regarding our ability to generate proteins with tailored functional properties such as ligand binding, improved stability, allostery, and catalytic activity. The power of directed protein evolution lies in its simplicity : First, a gene encoding a polypeptide is subjected to mutagenesis, and the resulting ensemble of mutated genes is expressed in a suitable cellular host. Second, the population of expressed proteins is subjected to a screening process. Often, multiple rounds of screening are required to isolate the rare clones within the population that can satisfy the functional screen. Third, DNA is isolated from the enriched clones and subjected to additional rounds of mutagenesis and screening under increasingly stringent conditions. This iterative process is repeated several times until either little functional improvement is observed between sequential rounds or proteins that satisfy the chosen criteria have been generated. There is a plethora of methods for generating an ensemble of mutated genes. Specifically, sequence diversity can be created by random mutagenesis, typically accomplished using error-prone polymerase chain reaction techniques ; by homologous in vitro recombination ; or by nonhomologous recombination. The latter involves two families of methods collectively known as incremental truncation for the creation of hybrid enzymes and sequence-homology independent protein recombination. Regardless of the means for generating sequence diversity, the next and by far the more technically challenging step in directed evolution is the screening of the resulting library of protein-expressing cells to isolate those that are expressing a protein variant that exhibits the desired function. It is fair to say that evolutionary protein design has been hampered by limitations in screening technologies. The quantitative determination of protein function for each and every clone in a library in a high-throughput fashion is a difficult and technically demanding task. In broad terms, there are four general strategies suitable for the screening of combinatorial protein libraries: phage display; biological assays that include selections and assays that use reporter enzymes [e.g., two-hybrid-like techniques for detecting interacting proteins ]; single-well assays using high-density microtiter well plates; and flow cytometry (FC) methods. Each of these methods has a different set of advantages and shortcomings.
Тези доповідей конференцій з теми "Quantitative determination for the biological activity using NMR"
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Grinco, Marina, Alexandru Marina, Natalia Birca, et al. "Pomolic acid from apple pomace: quantitative determination by heteronuclear two-dimentional QNMR and preparative isolation." In Scientific seminar with international participation "New frontiers in natural product chemistry". Institute of Chemistry, Republic of Moldova, 2023. http://dx.doi.org/10.19261/nfnpc.2023.ab14.
Повний текст джерелаАнотація:
Pomolic acid (PA) is a pentacyclic triterpenic acid isolated from apples by Brieskorn and Wunderer in 1967 [1]. Its highly relevant biological activity profile came recently into focus and there have been many reports on the content of PA in different plant sources [2]. Quite surprisingly, the general perception of low PA content in plants persists and this information hinders its broader investigation as a compound of pharmaceutical and nutraceutical potential. The main aim of the current work was quantitative determination of pomolic acid in apple pomace by two-dimensional heteronuclear NMR correlation spectroscopy. The dried and grinded apple pomace was extracted with solvents of moderate polarity, including ethanol, ethylacetate and dimethylcarbonate under conditions of ultrasound assisted extraction. The overall extraction time did not exceed 3 hours. Fractionated extracts were obtained on the separation of acidic and neutral part, followed by selective extraction with solvent series of increasing polarity (petroleum ether, dichloromethane, ethylacetate). The content of PA in the obtained extracts was determined basing on 2D NMR HSQC experiment according to a recently elaborated protocol [3]. The quantification was based on integration of cross peaks corresponding to selected protons of PA and methyl 2,4-dinitrobenzoate as internal standard. The results showed that the highest content of PA was observed in ethylacetate (13.7%) and dimethylcarbonate (9.5%) extracts. Ethanol extracts displayed lower PA content (4.6%) in extracts and higher material recovery as expressed in percentage PA of dry weight. It was also demonstrated that selective extracts fractionations can provide enriched PA samples on avoiding the laborious chromatographic separations. The broad availability of apple pomace as a by-product of apple juice production ensures an excellent perspective for the preparative isolation of pomolic acid which could be a valuable raw material for the food and pharmaceutical industries.
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Brito, Jordana T., Lucas H. Martorano, Ana Carolina F. de Albuquerque, et al. "ESPECTROSCOPIA COMPUTACIONAL APLICADA AO REASSINALAMENTO ESTRUTURAL DE MOLÉCULAS QUIRAIS: HELIANNUOL L." In VIII Simpósio de Estrutura Eletrônica e Dinâmica Molecular. Universidade de Brasília, 2020. http://dx.doi.org/10.21826/viiiseedmol202025.
Повний текст джерелаАнотація:
In the past, structure determination of natural products was an arduous process depending almost entirely on chemical synthesis, mainly by derivatization and degradation processes, taking years of effort. Recently, structural elucidation of natural products has undergone a revolution. Nowadays, with the combined use of different advanced spectroscopic methods, it became possible to completely assign the structure of natural products using small amounts of sample. However, despite the extraordinary ongoing advances in spectroscopy, the mischaracterization of natural products has been and remains a recurrent problem, especially in the presence of several chiral centers. The misinterpretation of NMR data has resulted in frequent reports addressing the issue of structural reassignment. In this context, a great effort has been devoted to the development of quantum chemical calculations to predict NMR parameters, and thus achieve a more accurate spectral interpretation. In this work, we applied a protocol for theoretical calculations of 1H NMR chemical shifts in order to establish the correct and unequivocal structure of Helianuol L, a member of the Heliannuol’s class, isolated from Helianthus annus. These secondary metabolites present a broad spectrum of biological activities, including the allelochemical activity, making them promising candidates as natural agrochemicals. It is worth mentioning, however, that the process of elucidating the structure of Heliannuol L was based on structural correlations with molecules already known in the literature, where few stereochemical analyses were performed. In this way, based on the fact that other compounds of the Heliannuol’s class had their structure previously reassigned, the verification of the proposed structure of Heliannuol L becomes of great importance.
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Organ, Adina, Mariana Jian, Vitalie Cobzac, et al. "Analytical studies on the fractionation products from lavender extracts." In Scientific seminar with international participation "New frontiers in natural product chemistry". Institute of Chemistry, Republic of Moldova, 2023. http://dx.doi.org/10.19261/nfnpc.2023.ab28.
Повний текст джерелаАнотація:
Lavender (Lavandula angustifolia) is a widespread aromatic plant exploited globally for essential oil production. It is known that the remaining wastes after industrial processing are rich in secondary metabolites with relevant biological activities [1]. In particular, triterpenic acids have recently attracted the interest of scientific community because of their broad activity spectrum which makes them very attractive for the use in cosmetics and healthcare products as functional compounds. The aim of this study was isolation and analytical studies on different fractions obtained from Lavandula angustifolia ethanolic extracts. The vegetal plant material represented wastes generated on the extraction of essential oil at industrial scale. The obtained integral extracts were mixed with different organic solvents of different polarity in acid and basic medium, thus obtaining a series of fractions with different content of secondary metabolites. The fractions with a high content of triterpenic acids were selected by using thin layer chromatography. The analytical experiments included determination of total polyphenols with the Folin-Ciocâlteu reagent, quantitative determination of flavonoids, FRAP reducing capacity test and qNMR determination of oleanolic, ursolic, pomolic and rosmarinic acids. According to the obtained results fractions showing higher total polyphenols (495.59 mg EGA/g of extract) were also rich in flavonoids (343.01 mg catechin equivalent/g of extract) demonstrating relevant reducing capacity (386.67 mg EGA/g of extract) and high rosmarinic acid content (cca. 250 mg/g of extract). The triterpenic acids have been found to predominate in less polar fractions.