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Abstract(s)
Os produtos naturais têm uma grande importância no tratamento de doenças desde os tempos antigos. De fato, na medicina tradicional, as plantas desempenham um papel crucial na prevenção de diferentes doenças e receberam especial atenção para novas opções terapêuticas. Neste contexto, a descoberta de novos agentes antimicrobianos é uma necessidade urgente para combater infeções oportunistas ou a resistência dos microrganismos aos antibióticos. Os produtos naturais alternativos encontrados nas plantas podem ter interesse, pois alguns extratos vegetais com os seus fitoquímicos são conhecidos por terem propriedades antimicrobianas, o que pode ter uma grande importância na terapêutica.
O objetivo deste estudo foi avaliar a atividade antimicrobiana de duas plantas utilizadas na medicina tradicional, mais especificamente o medronheiro e o pirliteiro. Para este fim, estudou-se a composição química das folhas desses dois arbustos, bem como suas propriedades biológicas.
O Arbutus unedo (medronheiro) pertence à família Ericaceae e na medicina tradicional tem sido utilizado como antisséptico, diurético, laxante e para tratar a hipertensão arterial. O Crataegus monogyna (pirliteiro) é uma espécie da família Rosaceae e vários estudos demonstraram que consegue reduzir alguns fatores de risco cardiovasculares e tem sido utilizado para o tratamento de algumas doenças, incluindo irritabilidade, insónia, confusão e perda de memória.
As folhas destas plantas foram extraídas com metanol e o extrato metanólico foi separado em frações usando solventes de polaridade crescente (N-hexano, éter dietílico e água). A caracterização fitoquímica dos extratos foi realizada utilizando métodos espectrofotométricos. O conteúdo fenólico total das amostras foi determinado pelo método de Folin-Ciocalteu e os flavonoides foram determinados com um método que usa o cloreto de alumínio. A atividade antioxidante foi avaliada pelo método do DPPH e pelo método que usa o sistema ß-caroteno/ácido linoleico. Os extratos brutos e as suas respetivas frações obtidas no processo de separação foram testados quanto à sua atividade antimicrobiana contra várias bactérias gram positivas e gram negativas e também leveduras.
Os resultados indicaram que o medronheiro possui uma quantidade maior de compostos fenólicos (202,53 ± 5,82 mg GAE / g de extrato) do que o pirliteiro (110,41 ± 1,47 mg GAE / g de extrato). Por outro lado, o pirliteiro apresentou maior teor em flavonoides (29,94 ± 1,85 mg QE / g de extrato e 26,85 ± 1,12 mg QE / g de extrato, para medronheiro e pirliteiro, respetivamente). Quanto à atividade de eliminação radicalar, a planta com maior potencial (IC50 inferior) foi o medronheiro, 17,41 ± 4,50 µg / mL contra 36,11 ± 2,11 µg / mL para o pirliteiro. Em comparação com os padrões utilizados na determinação da atividade antioxidante, ambas as plantas possuem atividade antioxidante, mas inferior aos padrões.
Em relação à atividade antimicrobiana, os extratos e as frações de medronheiro possuem propriedades antimicrobianas contra algumas bactérias, mas com os valores obtidos para a concentração mínima inibitória indicando que estes não possuem relevância terapêutica. No que diz respeito às leveduras, a maioria dos extratos e frações inibiu o crescimento das espécies C. tropicalis e C. lusitaniae. Os valores mais baixos de concentração mínima inibitória obtidos foram 0,063 mg/mL na fração apolar do extrato de pirliteiro em C. tropicalis e 0,008 mg/mL no extrato bruto e nas frações mais polares do extrato de medronheiro em C. lusitaniae. Por análise do potencial sinérgico dos extratos e frações mais relevantes com a Anfotericina B, verificou-se que existe um efeito aditivo ou sinérgico dos extratos com este antifúngico.
Em suma, estas duas plantas possuem atividade antioxidante e atividade antimicrobiana relevante contra leveduras, com potencial interação sinérgica com a Anfotericina B. Estes resultados são promissores para um possível uso dos seus extratos, ou apresentando-se como agentes com potencialidade no desenvolvimento de fármacos.
Since ancient times, natural products have a significant importance in disease treatment. In fact, in traditional medicine, plants play a crucial role in the prevention of different diseases and have received considerable attention for novel therapeutic options. In this context, the discovery of new antimicrobial agents to fight opportunistic infections or antibiotic microbial resistance is an urgent need. Alternative natural products from plants could be of interest because some plant extracts with their phytochemicals are known to have antimicrobial properties, which could be of great importance in therapeutic.The aim of this study was to evaluate the antimicrobial activity of two plants used in traditional medicine, more specifically strawberry tree and hawthorn. For this purpose, the chemical composition of the leaves of these two shrubs, as well as, their biological properties were studied. Arbutus unedo (strawberry tree) belongs to Ericaceae family and in traditional folk medicine has been used in antiseptics, diuretics, laxatives and to treat arterial hypertension. Crataegus monogyna (hawthorn) is a species of the Rosaceae family and several studies have shown that it could reduce some cardiovascular risk factors and been used to the treatment of some diseases including irritability, insomnia, confusion and memory loss. The leaves of these plants were extracted with methanol and the methanolic extract was separated into fractions using solvents of increasing polarity (N-hexane, diethyl ether and water). The phytochemical characterization of the extracts was performed using spectrophotometric methods. The total phenolic content in samples was determined using the Folin-Ciocalteu’s method and flavonoids were determined by a method using aluminum chloride. The antioxidant activity was evaluated by the DPPH method and through the use of ß-carotene/linoleic acid system. The crude extracts and their fractions obtained in the separation process were tested for their antimicrobial activity against several gram positive and gram negative bacteria and also yeasts. The results indicated that strawberry tree has a greater amount of phenolic components (202,53 ± 5,82 mg GAE/ g of extract) than the hawthorn (110,41 ± 1,47 mg GAE/ g of extract). On the other hand, the hawthorn had a higher content of flavonoids (29,94 ± 1,85 mg QE/ g of extract and 26,85 ± 1,12 mg QE/ g of extract for strawberry tree and hawthorn, respectively). Regarding radical scavenging activity, the plant with most potential (lower IC50), was strawberry tree, 17,41 ± 4,50 µg/mL against 36,11 ± 2,11 µg/mL for hawthorn. Compared with the standards used in the determination of the antioxidant activity, both plants have antioxidant activity but lower than the standards. Concerning to the antimicrobial activity, extracts and fractions of strawberry tree showed antimicrobial properties against some of the tested bacteria, but with the obtained minimum inhibitory concentration values indicating that these have no therapeutic relevance. Regarding yeasts, most of the extracts and fractions inhibited the growth of strain C. tropicalis and C. lusitaniae. The lowest values of minimum inhibitory concentration were 0,063 mg/mL in apolar fraction of hawthorn extract of C. tropicalis and 0,008 mg/mL in the crude extract and in the more polar fractions of strawberry tree extract in C. lusitaniae. By analyzing the synergistic potential of the most relevant extracts and fractions with Amphotericin B, it was verified that there was an additive or synergistic effect of the extracts with the antifungal. In sum, these two plants have antioxidant activity and relevant antimicrobial activity against yeasts. These results are promising for the possible use of these extracts, or for the pharmaceutical development of new drugs.
Since ancient times, natural products have a significant importance in disease treatment. In fact, in traditional medicine, plants play a crucial role in the prevention of different diseases and have received considerable attention for novel therapeutic options. In this context, the discovery of new antimicrobial agents to fight opportunistic infections or antibiotic microbial resistance is an urgent need. Alternative natural products from plants could be of interest because some plant extracts with their phytochemicals are known to have antimicrobial properties, which could be of great importance in therapeutic.The aim of this study was to evaluate the antimicrobial activity of two plants used in traditional medicine, more specifically strawberry tree and hawthorn. For this purpose, the chemical composition of the leaves of these two shrubs, as well as, their biological properties were studied. Arbutus unedo (strawberry tree) belongs to Ericaceae family and in traditional folk medicine has been used in antiseptics, diuretics, laxatives and to treat arterial hypertension. Crataegus monogyna (hawthorn) is a species of the Rosaceae family and several studies have shown that it could reduce some cardiovascular risk factors and been used to the treatment of some diseases including irritability, insomnia, confusion and memory loss. The leaves of these plants were extracted with methanol and the methanolic extract was separated into fractions using solvents of increasing polarity (N-hexane, diethyl ether and water). The phytochemical characterization of the extracts was performed using spectrophotometric methods. The total phenolic content in samples was determined using the Folin-Ciocalteu’s method and flavonoids were determined by a method using aluminum chloride. The antioxidant activity was evaluated by the DPPH method and through the use of ß-carotene/linoleic acid system. The crude extracts and their fractions obtained in the separation process were tested for their antimicrobial activity against several gram positive and gram negative bacteria and also yeasts. The results indicated that strawberry tree has a greater amount of phenolic components (202,53 ± 5,82 mg GAE/ g of extract) than the hawthorn (110,41 ± 1,47 mg GAE/ g of extract). On the other hand, the hawthorn had a higher content of flavonoids (29,94 ± 1,85 mg QE/ g of extract and 26,85 ± 1,12 mg QE/ g of extract for strawberry tree and hawthorn, respectively). Regarding radical scavenging activity, the plant with most potential (lower IC50), was strawberry tree, 17,41 ± 4,50 µg/mL against 36,11 ± 2,11 µg/mL for hawthorn. Compared with the standards used in the determination of the antioxidant activity, both plants have antioxidant activity but lower than the standards. Concerning to the antimicrobial activity, extracts and fractions of strawberry tree showed antimicrobial properties against some of the tested bacteria, but with the obtained minimum inhibitory concentration values indicating that these have no therapeutic relevance. Regarding yeasts, most of the extracts and fractions inhibited the growth of strain C. tropicalis and C. lusitaniae. The lowest values of minimum inhibitory concentration were 0,063 mg/mL in apolar fraction of hawthorn extract of C. tropicalis and 0,008 mg/mL in the crude extract and in the more polar fractions of strawberry tree extract in C. lusitaniae. By analyzing the synergistic potential of the most relevant extracts and fractions with Amphotericin B, it was verified that there was an additive or synergistic effect of the extracts with the antifungal. In sum, these two plants have antioxidant activity and relevant antimicrobial activity against yeasts. These results are promising for the possible use of these extracts, or for the pharmaceutical development of new drugs.
Description
Keywords
Atividade Antimicrobiana Atividade Antioxidante Compostos Fenólicos Medronheiro Pirliteiro