Preparação de extratos do género Plectranthus e avaliação da atividade biológica
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2020
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As plantas medicinais e os seus princípios ativos são muito importantes para a obtenção de novos compostos. Neste trabalho foram estudados dois extratos das plantas Plectranthus xerophilus Codd. e P. madagascariensis (Pers.) Benth (família Lamiaceae). A atividade antimicrobiana dos extratos preparados foi avaliada, pelo método de microdiluição contra as bactérias Staphylococcus aureus, Bacillus subtillis, Enterococcus faecalis, Escherichia coli e Pseudomonas aeruginosa.
O extrato acetónico de P. xerophilus foi preparado pelo método de extração por ultrassons (10% m/v) que demonstrou atividade antimicrobiana (valor de Concentração Mínima Inibitória - CMI de 62,5 μg/mL), contra a bactéria S. aureus. Os óleos essenciais de P. madagascariensis, obtidos por hidrodestilação (método de Clevenger), demonstraram atividade antimicrobiana contra a bactéria E. faecalis (valor de CMI de 15,63 μg/mL). Os restantes ensaios não demonstraram atividade relevante em comparação com os controlos positivos, nas bactérias testadas. Dado que o extrato de P. madagascariensis demonstrou possuir uma elevada atividade antimicrobiana, procedeu-se ao isolamento do composto maioritário, 6,7-dehidroroileanona (DHR), obtendo-se um rendimento de 47,28 % (m/m; massa composto/massa extrato).
A atividade antimicrobiana demonstrada pelo composto DHR deve ser elucidada, nomeadamente quanto ao seu mecanismo de ação, para o desenvolvimento de novos fármacos, comprovando-se, assim, a aposta nas plantas medicinais.
Medicinal plants and their active principles are very important in obtaining new compounds. In this work two extracts of Plectranthus xerophilus Codd and P. madagascariensis (Pers.) Benth (Lamiaceae family) plants were studied. The antimicrobial activity of the prepared extracts was evaluated through the microdilution method against Staphylococcus aureus, Bacillus subtillis, Enterococcus faecalis, Escherichia coli and Pseudomonas aeruginosa bacteria. The acetonic P. xerophilus extract was prepared by the ultrasound extraction method (10% w/v) which demonstrated antimicrobial activity (Minimum Inhibitory Concentration value - MIC 62,5 μg/mL) against the S. aureus bacteria. P. madagascariensis essential oils obtained by hydro distillation (Clevenger method), demonstrated antimicrobial activity against E. faecalis bacteria (MIC value of 15,63 μg/mL). The remaining assays showed no relevant activity compared to positive controls in the tested bacteria. Since P. madagascariensis extract was shown to have high antimicrobial activity, the major compound was isolated, 6,7-dehydroroyleanone (DHR), yielding 47,28% (w/w; compound mass/mass extract). The antimicrobial activity demonstrated by the DHR compound should be elucidated, in particular as to its action mechanism, for the development of new drugs, thus proving the bet on medicinal plants.
Medicinal plants and their active principles are very important in obtaining new compounds. In this work two extracts of Plectranthus xerophilus Codd and P. madagascariensis (Pers.) Benth (Lamiaceae family) plants were studied. The antimicrobial activity of the prepared extracts was evaluated through the microdilution method against Staphylococcus aureus, Bacillus subtillis, Enterococcus faecalis, Escherichia coli and Pseudomonas aeruginosa bacteria. The acetonic P. xerophilus extract was prepared by the ultrasound extraction method (10% w/v) which demonstrated antimicrobial activity (Minimum Inhibitory Concentration value - MIC 62,5 μg/mL) against the S. aureus bacteria. P. madagascariensis essential oils obtained by hydro distillation (Clevenger method), demonstrated antimicrobial activity against E. faecalis bacteria (MIC value of 15,63 μg/mL). The remaining assays showed no relevant activity compared to positive controls in the tested bacteria. Since P. madagascariensis extract was shown to have high antimicrobial activity, the major compound was isolated, 6,7-dehydroroyleanone (DHR), yielding 47,28% (w/w; compound mass/mass extract). The antimicrobial activity demonstrated by the DHR compound should be elucidated, in particular as to its action mechanism, for the development of new drugs, thus proving the bet on medicinal plants.
Descrição
Orientação: Patrícia Rijo
Palavras-chave
MESTRADO INTEGRADO EM CIÊNCIAS FARMACÊUTICAS, CIÊNCIAS FARMACÊUTICAS, PHARMACEUTICAL SCIENCES, PLANTAS MEDICINAIS, MEDICINAL PLANTS, EXTRATOS VEGETAIS, VEGETAL EXTRACTS