Добірка наукової літератури з теми "Plectrantus spp"

The Plectranthus genus is commonly used in traditional medicine due to its potential to treat several illnesses, including bacterial infections and cancer. As such, aiming to screen the antibacterial and cytotoxic activities of extracts, sixteen selected Plectranthus species with medicinal potential were studied. In total, 31 extracts obtained from 16 Plectranthus spp. were tested for their antibacterial and anticancer properties. Well diffusion method was used for preliminary antibacterial screening. The minimum inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) values of the five most active acetonic extracts (P. aliciae, P. japonicus, P. madagascariensis var. “Lynne”, P. stylesii, and P. strigosus) were determined. After preliminary toxicity evaluation on Artemia salina L., their cytotoxic properties were assessed on three human cancer cell lines (HCT116, MCF-7, and H460). These were also selected for mechanism of resistance studies (on NCI-H460/R and DLD1-TxR cells). An identified compound—parvifloron D—was tested in a pair of sensitive and MDR-Multidrug resistance cancer cells (NCI-H460 and NCI-H460/R) and in normal bronchial fibroblasts MRC-5. The chemical composition of the most active extract was studied through high performance liquid chromatography with a diode array detector (HPLC-DAD/UV) and liquid chromatography–mass spectrometry (LC–MS). Overall, P. strigosus acetonic extract showed the strongest antimicrobial and cytotoxic potential that could be explained by the presence of parvifloron D, a highly cytotoxic diterpene. This study provides valuable information on the use of the Plectranthus genus as a source of bioactive compounds, namely P. strigosus with the potential active ingredient the parvifloron D.

SUMMARY Resistance to use antifungal drugs is a great concern seeking for scientists to discover new products to treat fungal infections. The aim of this study was to evaluate the antioxidant and antifungal activities of essential oils and extracts of Plectranthus grandis and Plectranthus ornatus against Trichophyton rubrum and Microsporum canis dermatophytes strains. Extracts were obtained from leaves by maceration in ethanol (96%) during 7 days. The oils were obtained by hydrodistillation and analyzed by gas chromatography/mass spectrometry. A total of 25 components were identified, as major constituents the sesquiterpenes β-caryophyllene, α-copaene, germacrene, β-caryophyllene and caryophyllene oxide. Antioxidant activities were evaluated using DPPH scavenging assay and antifungal action was determined by the broth microdilution method. The decocts obtained from the extraction of essential oil presented a greater antioxidant action when compared with the essential oils, with IC50 values of 12.35 μg/mL and 15.69 μg/mL to P. ornatus and P. grandis, respectively. Natural products presented significant antifungal activity, with MIC values ranging from 0.078 mg/mL to 0.31 mg/mL for all strains. The synergistic activity between Plectranthus spp. extracts and ketoconazole demonstrated a fungal growth inhibitory action when combined with a standard antifungal drug, indicating its potential for use in preventive veterinary medicine to treat dermatophytoses.

Plectranthus spp. is widely known for its medicinal properties and bioactive metabolites. The cytotoxic and genotoxic properties of the four known abietane diterpenoids: 7α-Acetoxy-6β-hydroxyroyleanone (Roy), 6,7-dehydroroyleanone (Deroy), 7β,6β-dihydroxyroyleanone6 (Diroy), and Parvifloron D (Parv), isolated from P. madagascariensis (Roy, DeRoy, and Diroy) and P. ecklonii (Parv) were evaluated. The tested compounds showed cytotoxic effects against the human leukemia cell line CCRF-CEM and the lung adenocarcinoma cell line A549. All tested compounds induced apoptosis by altering the level of pro- and anti-apoptotic genes. The results show that from the tested diterpenoids, Roy and Parv demonstrated the strongest activity in both human cancer cell lines, changing the permeability mitochondrial membrane potential and reactive oxygen species (ROS) levels, and possibly inducing mtDNA or nDNA damage. In conclusion, the abietane diterpenoids tested may be used in the future as potential natural chemotherapeutic agents

The use of herbal products for the treatment, prevention and cure of diseases is one of the oldest human medicinal practices. In fact, the majority of the population in developing countries depend on ancestral plant knowledge for healthcare. However, there is still a gap between progress observed in clinical pharmacy and in the field of herbal and traditional medicine, as there remain many natural products with biological activity to be identified. Plectranthus species (Lamiaceae family) have a widespread ethnobotanical use and are often cited by its medicinal properties and application, particularly in folk medicine. They contain many antioxidant compounds and exhibit several effects (anti-inflammatory, antimicrobial and antifungal) which suggest that Plectranthus may be a promising genus for the discovery of medicinal compounds. Thus, the isolation of secondary metabolite compounds from the Plectranthus spp. is important to scientifically validate the popular uses of these plants and to find new sources of potentially economically important products or compounds, which can be transformed into active pharmaceutical ingredients. Furthermore, the cytotoxicity evaluation of the plant extracts and their active ingredients are required for their effective and safe therapeutic use. This work enumerates the compounds isolated to date from Plectranthus ecklonii Benth., extracts and their biological activities. The HPLC analysis presented is part of an ongoing project at CBIOS of identification, quantification and evaluation of the bioactive components (in particular, diterpenes and hydrocinnamic acids) in different species of Plectranthus.

Plectranthus species (Lamiaceae) have been employed in traditional medicine and this is now validated by the presence of bioactive abietane-type diterpenoids. Herein, sixteen Plectranthus acetonic extracts were prepared by ultrasound-assisted extraction and their biological activity was screened. The antimicrobial activity of each extract was screened against yeasts, and Gram-positive and Gram-negative bacteria. The P. hadiensis and P. mutabilis extracts possessed significant activity against Staphylococcus aureus and Candida albicans (microdilution method). Moreover, all extracts showed antioxidant activity using the DPPH method, with P. hadiensis and P. mutabilis extracts having the highest scavenging activities. Selected by the Artemia salina model, P. hadiensis and P.ciliatus possessed low micromolar anti-proliferative activities in human colon, breast, and lung cancer cell lines. Furthermore, the most bioactive extract of P. hadiensis leaves and the known abietane diterpene, 7α-acetoxy-6β-hydroxyroyleanone isolated from this plant, were tested against the aggressive type triple negative breast cancer (MDA-MB-231S). P. hadiensis extract reduced the viability of MDA-MB-231S cancer cell line cells, showing an IC50 value of 25.6 µg/mL. The IC50 value of 7α-acetoxy-6β-hydroxyroyleanone was 5.5 µM (2.15 µg/mL), suggesting that this lead molecule is a potential starting tool for the development of anti-cancer drugs.

Natural compounds isolated from plants are excellent starting points in drug design and have been widely studied as anticancer agents; they hence find use in a considerable proportion of anticancer drugs. The genus Plectranthus (Lamiaceae) comprises a large and widespread group of species with various applications in traditional medicine. Therefore, the aim of the present study was to determine the effectiveness of treatment with four abietane diterpenoids isolated from P. madagascariensis and P. ecklonii, 6,7-dehydroroyleanone, 7β,6β-dihydroxyroyleanone, 7α-acetoxy-6β-hydroxyroyleanone and parvifloron D, in initiating apoptosis in a glioma cell line. The pure compounds were found to exhibit anticancer effects in primary H7PX glioma cells line by inducing apoptosis G2/M cell cycle arrest and double-strand breaks, indicated by increased levels of phosphorylated H2A.X and decreasing mitochondrial membrane potential; they also influenced the expression of pro- and anti-apoptotic genes (Bax, Bcl-2, TP53, or Cas-3). Our findings indicate that these compounds may offer potential as beneficial antitumor drugs but further in vivo studies are needed.

The aim of this diploma thesis was to determine the optimal extraction conditions for obtaining an extract from the plant Plectranthus amboinicus. Plectranthus amboinicus is an aromatic herb of the Lamiaceae family containing a large number of bioactive compounds. Because of this, it has a number of biological effects – antimicrobial, anti-inflammatory, antioxidant, analgesic, etc. To maintain the maximum of sensory and nutritionally valuable components of P. amboinicus, a simple maceration of fresh chopped herb was chosen. Maceration was performed under the following conditions: 40 minutes at 40 ° C, solvent 40% ethanol, weight 20 g of herb per 100 ml of solvent. The extract prepared under these optimal conditions was comprehensively characterized in terms of the content of total polyphenols, their concentration was determined to 0,08 ± 0,02 mgGEA·ml-1, which corresponds to 0,40 ± 0,07 mgGEA·g-1 of the plant. The antioxidant activity of the extract was 241,24 ± 29,24 µgTEAC·ml-1 and the radical scavenging activity of ABTS•+ was determined to be 49,29 ± 5,97 %. The antimicrobial activity was verified by the agar well diffusion method. Two types of bacteria were selected for the determination – gram-positive Bacillus cereus, gram-negative Escherichia coli and yeast Candida glabrata. The results showed that the extracts have the highest antimicrobial activity against B. cereus. There were 64 volatile aromatic compounds identified in the extract, with monoterpenes and sesquiterpenes dominating. The obtained results confirm that P. amboinicus, or its prepared extract, has a good potential for use as a new and non-traditional flavor in various foods and delicacies, which can also increase their nutritional value.

Plectranthus amboinicus is a herb that was found to have a lot of bioactive compounds, most of them are polyfenolic compounds. Extraction is neccesary to obtain bioactive compounds and to use them subsequently in food or cosmetic industry. Three methods of extraxtion – maceraction, PHWE and PFE, were used in this study. The best yield of extracted polyfenols was observed by maceration. Maceration was, in the next step, optimized using mathematical statistical method of planned experiment (DOE). The optimal conditions found for extraction were: temperature 60 °C, solvent 40% ethanol, time 90 minutes, solid-solvent ratio 1:10. Total phenolic compunds content in this extract was 0,18 ± 0,05 mgGAE·ml-1, which means 1,83 ± 0,53 mgGAE·g-1 of plant. The antioxidant activity was 148,69 ± 26,92 gTEACml-1. Percentage of radical scavenging activity ABTS•+ was 30,03 ± 5,44 %. Further, 27 of volatile aroma compounds were identified in optimal extract, the most important were: -selinene (16,67 %), trans--bergamotene (14,22 %), caryophyllene (14,11 %), 3-carene (8,22 %), -copaene (7,55 %), -terpinene (6,28 %), humulene (5,87 %), cadina-1(10)-4-diene (5,19 %).

Trabalho Final de Mestrado Integrado, Ciências Farmacêuticas, Universidade de Lisboa, Faculdade de Farmácia, 2017
Nature is an attractive source of new therapeutic candidate compounds. The isolation of new natural products can provide novel scaffolds with potential biological activities, which may trigger the drug development as seen in the past. Plectranthus genus holds valuable biologically active diterpenes compounds. An interesting abietane diterpenoid is present in high amounts in the essential oil (EO) of Plectranthus madagascariensis named 6,7-dehydroroyleanone (DHR). In previous studies, the DHR has exhibit cytotoxic activity. This study is focused on the synthesis of new abietane diterpenoid derivatives 1 – 6 by Mitsunobu reaction and benzoylation using DHR as a starting material. DHR was isolated from the EO of P. magadascariensis by hydrodistillation using the Clevenger apparatus followed by dry-column flash chromatography and recrystallization. After the isolation of DHR its structure was assigned by spectroscopic methods. All the structures of the new compounds 1 – 6 were established from NMR spectroscopic data. The preliminary toxicity of the new abietane diterpenoid derivatives 1 – 6 was evaluated through the brine shrimp assay. This lethality test showed an improved toxicity (from LC = 45.64% to 68.34% at 100 ppm) of the majority of novel synthesized compounds given the DHR chemical modifications (LC = 38.68% at 100 ppm). The most toxic DHR derivative was compound 2 (LC = 68.34% at 100 ppm) synthesized by Mitsunobu reaction. All the derivatives with alkoxy group 1 – 5 displayed improved toxic activity. Furthermore, it appears that the position C-12 is important for the toxic activity. Further studies regarding structure-activity relationship (SAR) should be performed.
A natureza é uma fonte atrativa de novos compostos terapêuticos. O isolamento de novos produtos naturais pode fornecer novas moléculas com potencial atividade biológica, o que pode vir a desencadear o desenvolvimento de novos fármacos como relatado no passado. O género Plectranthus contém compostos diterpénicos biologicamente ativos. Um diterpeno do tipo abietano particularmente interessante está presente no óleo essencial (EO) do Plectranthus madagascariensis, denominado de 6,7-dehidroroileanona (DHR). Os estudos anteriores demonstraram que a DHR possui atividade citotóxica. O presente estudo está focado na síntese de novos derivados diterpénicos do tipo abietano 1 – 6 através da reação de Mitsunobu e da benzoilação, utilizando a DHR como material de partida. A DHR foi isolada do EO do P. magadascariensis por hidrodestilação recorrendo-se ao aparelho de Clevenger seguido de cromatografia flash em coluna seca e posterior recristalização. Após o isolamento da DHR, a sua estrutura foi identificada por métodos espectroscópicos. Todas as estruturas dos novos compostos 1 a 6 foram estabelecidas a partir de dados espectroscópicos de RMN. A toxicidade preliminar dos novos derivados diterpénicos 1 – 6 foi determinada através do ensaio da Artemia salina. Este teste de letalidade demonstrou um aumento da toxicidade dos novos compostos sintetizados (de LC = 45.64% até 68.34% a 100 ppm), dadas as modificações químicas na estrutura da DHR (LC = 38.68% a 100 ppm). O derivado mais tóxico da DHR foi o composto 2 (LC = 68.34% a 100 ppm) sintetizado através da reação de Mitsunobu. Todos os derivados com grupos alcóxi de 1 – 5 apresentaram uma toxicidade melhorada. Além disso, parece que a posição C-12 é importante para a atividade tóxica, embora a natureza do grupo alquilo inserido seja relevante para a atividade biológica. Mais estudos sobre a relação estrutura-atividade (SAR) devem ser realizados.

Tese de mestrado, Ciências Biofarmacêuticas, Universidade de Lisboa, Faculdade de Farmácia, 2016
This dissertation focused on the biological activity screening of several Plectranthus spp. plants, aiming to unravell novel ethnopharmacological roles and further research, of several extracts (methanol, ethyl acetate, acetone and water) and isolated compounds. Previous evidences on interesting biological activities of Plectranthus spp. constituents, directed the study for antioxidant, anti-skin ageing, anti-inflammatory, and anti-mycobacterial activities. Antioxidant results revealed an increased activity of the methanol extracts (20-76%), due to the presence of polyphenols widely known as antioxidants. Moreover, P. grandidentatus (62.3 ± 0.43%) and P. ecklonii (55.5 ± 1.66%) registered a high scavenging activity in the ethyl acetate extract, in comparison with quercetin (89.0 ± 2.5%), most likely due to the presence of abietane diterpenes. Acetylcholinesterase (AChE) was studied in vitro to evaluate the enzymatic inhibition, due to recent discoveries on non-neuronal cholinergic system in the skin. This assay showed that the Plectranthus spp. organic extracts did not significantly inhibited AChE. Concerning the tyrosinase inhibition assay, it was observed a high inhibition for the P. ecklonii methanol (65.9 ± 3.42%), P. grandidentatus acetone (67.9 ± 3.55%), and P. saccatus acetone (56.5 ± 5.68%) organic extracts. On the other hand, the aqueous extract of P. porcatus was the only one that showed enzymatic inhibition (65.0 ± 8.67%). From the tested isolated compounds, abietane diterpenes, mainly present in the organic extracts of P. grandidentatus, P. madagascariensis, and P. ecklonii were highly active against tyrosinase, in more than 46% and up to 75%, especially compared to kojic acid (92.9 ± 7.28%). In the collagenase assay, all tested extracts and compounds showed a high enzymatic inhibition which was in the range of 28-76%. The higher inhibition results were obtained from P. neochilus methanol extract (76.4 ± 2.09%), P. ecklonii aqueous extract inhibited (75.59 ± 6.5%) and rosmarinic acid (44.78 ± 4.53%), in comparison with epigallocatechin gallate (93.1 ± 5.27%). In contrast to the results of the previous enzymatic assays, the anti-elastase assay revealed that in general the extracts did not decrease elastase activity (30-42%). Nonetheless, the isolated compounds were tested, and they were able to highly inhibit elastase activity. Particularly, the oleanolic:ursolic acids mixture (1:4) with 63.4 ± 2.56% and Parvifloron D with 52.8 ± 3.76%, were the most efficient in elastase inhibition specially compared with ursolic acid used as positive control (69.9 ± 3.65%). The anti-inflammatory assay was performed by the quantification of NO production using the Griess reaction. The non-cytotoxic isolated compounds revealed to be unable to reduce NO production, after LPS stimulated inflammation (ranging from 16-23 μM), in comparison with the normal quantities of NO production within the cells (17.7 ± 0.67 μM), and with the positive control L-NAME that decreased NO until reaching 3.9 ± 0.24 μM. Finally, the preliminary results of Mycobacterium tuberculosis H37Rv growth assay, revealed low CFU/mL (dilution 10-3) especially regarding one halimane diterpene compound (2.1×105 CFU/mL), similar to the positive controls isoniazid (1.2×105 CFU/mL), and ethambutol (2.0×105 CFU/mL), suggesting a potential alternative for further anti-tubercular studies. Overall, according to the references of this study, this was the first report on Plectranthus spp., concerning the assays of skin-related enzymatic inhibition in vitro, anti-inflammatory assay, and Mycobacterium tuberculosis H37Rv growth, with a preliminary scientific validation upon known ethnopharmacological uses.
As plantas do género Plectranthus L’Héritier (família Lamiaceae) são selecionadas em várias investigações científicas devido aos vários usos etnofarmacológicos pelas populações indígenas, e facilidade de crescimento em zonas temperadas. Estas plantas são compostas por cerca de 350 espécies reconhecidas pelos seus óleos essenciais e compostos terpénicos. Nesta dissertação pretendeu-se desenvolver e complementar o screening de várias atividades biológicas, a partir de extratos e compostos isolados de sete espécies de Plectranthus (P. grandidentatus Gürke, P. ecklonii Benth., P. ornatus Codd., P. madagascariensis (Pers.) Benth., P. porcatus van Jaarsv. & P.J.D.Winter, P. neochilus Schltr., e P. prostratus Gürke). Estes estudos biológicos envolveram a pesquisa de atividades antioxidante, anti-envelhecimento da pele, anti-inflamatória e anti-micobacteriana. Foram obtidos vinte e oito extratos (sete aquosos e vinte e um orgânicos, nomeadamente de acetona, metanol e acetato de etilo) de todas as plantas em estudo, obtendo-se os resíduos secos (mg de extrato/g de planta). Nos resultados preliminares da atividade antioxidante executada pelo método da recaptação do radical DPPH, verificou-se que os extratos de metanol detiveram os valores mais elevados de recaptação de radicais livres (20-76%), e, portanto, de maior atividade antioxidante. Concluiu-se que esta atividade poderá estar relacionada com as elevadas quantidades em polifenóis nos extratos metanólicos, amplamente citados como antioxidantes. Adicionalmente, foi também registada uma elevada atividade antioxidante para os extratos de acetato de etilo de P. ecklonii (55.5 ± 1.66%) e P. grandidentatus (62.3 ± 0.43%), muito provavelmente devido à presença de diterpenos abietânicos. Na verdade, estes foram os resultados que demonstraram maior atividade antioxidante comparável ao controlo positivo usado, quercetina (89.0 ± 2.5%). A acetilcolinesterase (AChE, EC 3.1.17), conhecida pela sua ação na terminação do impulso nervoso pela hidrólise da acetilcolina, produzindo colina, foi estudada in vitro usando o método de Ellman, de modo a avaliar a inibição enzimática pelos extratos e/ou compostos isolados. Este ensaio foi realizado com base nos dados recentes da literatura, evidenciando um sistema colinérgico não-neuronal pela presença de acetilcolina na pele (humana). Com base nos resultados obtidos, foi possível concluir que nenhum dos vinte e um extratos orgânicos estudados inibiram a AChE no ensaio enzimático in vitro. Relativamente aos ensaios in vitro de inibição enzimática relacionada com a pele, o ensaio de inibição da tirosinase (EC 1.14.18.1), uma monooxigenase de cobre que catalisa a síntese de melanina pela produção de L-DOPA a partir de L-tirosina, revelou que os extratos orgânicos de P. ecklonii metanol (65.9 ± 3.42%), P. grandidentatus acetona (67.9 ± 3.55%), e P. saccatus acetona (56.5 ± 5.68%), diminuíram significativamente a atividade enzimática da tirosinase. Por outro lado, o extrato aquoso de P. porcatus foi o único a exibir inibição enzimática da tirosinase (65.0 ± 8.67%). De modo a confirmar a atividade registada para os extratos, foram testados os compostos isolados. De facto, os compostos abietânicos (maioritariamente presentes nos extratos orgânicos de P. grandidentatus, P. madagascariensis, e P. ecklonii) demonstraram forte atividade contra a tirosinase, em mais de 46% e até 75%, especialmente em comparação com o ácido kójico (92.9 ± 7.28%). Relativamente ao ensaio enzimático de inibição da colagenase (EC 3.4.24.3, metaloproteinase envolvida na clivagem do colagénio), todas as amostras inibiram, de um modo geral, a atividade enzimática (28-76%). Na verdade, o extrato metanólico de P. neochilus inibiu a colagenase em 76.4 ± 2.09%, bem como o extrato aquoso de P. ecklonii (75.6 ± 6.5%) e o composto ácido rosmarínico em 44.78 ± 4.53%. Estes resultados preliminares sugerem que a presença de compostos polifenólicos e diterpenos abietânicos nos extratos de Plectranthus, têm uma elevada eficiência inibitória da colagenase semelhante à epigallocatequina galhato (93.1 ± 5.27%). Em contraste com o que foi obtido nos ensaios enzimáticos da tirosinase e da colagenase, no ensaio enzimático de inibição da elastase (EC 3.4.21.36, protease de serina envolvida na quebra da elastina) não foi observada a diminuição da atividade enzimática após tratamento com os vinte e oito extratos de Plectranthus (30-42% de inibição enzimática). No entanto, os compostos isolados testados demonstraram uma elevada inibição. Particularmente, esta ação foi observada para a mistura de ácidos oleanólico:ursólico 1:4 (63.4 ± 2.56%) e para a Parviflorona D (52.8 ± 3.76%), em comparação com o ácido ursólico usado como controlo positivo (69.9 ± 3.65%). De um modo geral, os extratos e/ou compostos isolados das sete espécies de Plectranthus, revelaram uma elevada capacidade, como redutores da híper pigmentação da pele (provocada pela atividade excessiva da tirosinase), e na manutenção da integridade dérmica, através da manutenção de colagénio e elastina, pela inibição da colagenase e da elastase. Assim, em conjunto com a atividade antioxidante contra a produção de ROS, e na inibição de enzimas relacionadas com a integridade dérmica e pigmentação, será possível o desenvolvimento de uma aplicação cosmética em ensaios futuros. Por outro lado, a capacidade anti-inflamatória dos compostos foi avaliada através da inibição da produção de NO, usando a reação de Griess. Assim, após a avaliação da citotoxicidade dos compostos testados (em várias concentrações) através do ensaio MTT, foi medida a inflamação em células de macrófagos RAW 264.7. Após estimulação da inflamação celular com LPS, e tratamento com os compostos não tóxicos, este ensaio revelou que os compostos testados não foram capazes de reduzir a produção de NO (16-23 μM), em comparação com a quantidade de NO produzida naturalmente pelas células (17.7 ± 0.67 μM) e com o L-NAME, usado como controlo positivo (3.9 ± 0.2 μM). Uma vez que a inflamação não é apenas proporcional à produção de NO, mas também de outros mediadores inflamatórios, será necessário expandir a investigação desta atividade biológica. De modo a compreender, se de facto, os compostos isolados de Plectranthus são anti-inflamatórios por outros mecanismos, como por exemplo, por inibição enzimática da ciclooxigenase-2 (COX-2). Finalmente, foi avaliado o crescimento de Mycobacterium tuberculosis (Mtb) H37Rv após a infeção de macrófagos, derivados de células mononucleares do sangue periférico (PBMC). Numa primeira abordagem, o crescimento bacteriano foi monitorizado pela contagem de unidades formadoras de colónias (UFC), nas primeiras horas de infeção, e 13 dias após infeção e tratamento com os compostos selecionados. Após a normalização dos valores de UFC/mL, os resultados revelaram uma diminuição substancial de colónias de Mtb (na diluição 10-3), apenas após o tratamento com um composto halimano obtido por hemi-síntese (2.1×105 UFC/mL). Este resultado foi muito semelhante ao dos controlos positivos aplicados, isoniazida (1.2×105 UFC/mL) e etambutol (2.0×105 UFC/mL), sugerindo a possível aplicabilidade deste tipo de compostos em estudos futuros de terapia anti-tuberculose. Dado o resultado deste halimano na notável diminuição de colónias de Mtb, será relevante prosseguir na possível avaliação do mecanismo de ação que conduziu à inibição do crescimento bacteriano. Para tal, poder-se-ão aplicar técnicas de Western blot e imunofluorescência usando marcadores de autofagia, e avaliar a biogénese do fagolisossoma pelos macrófagos infetados. No geral, de acordo com as referências consultadas, são aqui reportados os primeiros estudos em ensaios de inibição de enzimas relacionadas com a pele, na atividade anti-inflamatória por via do NO, e na atividade anti-tuberculose de extratos e compostos isolados de Plectranthus. Os resultados obtidos nesta dissertação fornecem uma validação científica preliminar, sobre os usos amplamente conhecidos e reportados, por estas plantas medicinais. Na verdade, são necessários mais estudos na pesquisa de novos alvos terapêuticos mais específicos e com menos efeitos adversos, a partir das atividades etnofarmacológicas de Plectranthus reportadas até agora. Assim como validações científicas no uso de produtos à base de plantas usados no tratamento, cura e prevenção de doenças. Uma vez que os produtos naturais representam uma fonte única de compostos protótipo no desenvolvimento de novos fármacos, os metabolitos secundários isolados de Plectranthus revelam neste estudo, o seu potencial no design de novos medicamentos.
The presented thesis project was performed at the Food Sciences and Phytochemistry research group at the Research Center for Biosciences & Health Technologies (CBIOS) of Universidade Lusófona de Humanidades e Tecnologias (ULHT), under the supervision of Professor Doctor Patrícia Dias Mendonça Rijo, Ph.D and co-supervision of Professor Doctor Célia Maria Cardona Faustino, Ph.D. Part of the research was developed under the Short-Term Scientific Mission of COST action CM1407 entitled “Natural diterpenoids as potential anti-tubercular drugs”, developed at the National Institute for the infectious Disease Lazzaro Spallanzani, Laboratorio di Biologia Cellulare e Microscopia Elettronica, Rome, Italy, under the supervision of Doctor Gian Maria Fimia, and co-supervision of Doctor Alessandra Romagnoli. Additionally, some research was developed at the Centre for Marine Sciences (CCMAR), at the MARbiotech laboratories, University of Algarve, Faro, Portugal, under the supervision of Doctor Luísa Custódio.