Atividade Antibacteriana dos Extratos Etanolícos do Caule e da Folha de Qualea parviflora Mart. (Pau-terra)

Abstract

A resistência aos antimicrobianos por micro-organismos patogênicos é consequência, principalmente, do uso irracional de antibióticos e constitui uma ameaça para o controle das doenças infecciosas. Estudos das atividades antibacterianas de extratos de plantas podem fornecer alternativas para o tratamento antimicrobiano e, por isso têm despertado interesse pela investigação para o potencial da flora brasileira. Objetivou-se analisar a possível atividade antibacteriana da espécie Qualea parviflora Mart. (Pau-terra). Os ensaios foram realizados por difusão em discos previamente sensibilizados com extratos obtidos por maceração do caule e folhas nas concentrações de 50 e 100% (etanol 99,5ºGL como extrator). Realizaram-se testes para cepas Gram-positivas (Staphylococcus aureus e Streptococcus pyogenes) e Gram-negativas (Escherichia coli). Os discos sensibilizados foram dispostos nas placas de cultivo e essas incubadas a 37 ºC/24 horas. Os halos de inibição foram analisados por leitura visual. Os extratos concentrados (100%) da casca e folha apresentaram inibição contra Gram-positivas e Gram-negativas, sendo o obtido da folha mais eficaz. Na concentração de 50%, a inibição somente foi observada com o macerado das folhas. Os extratos da maceração das folhas apresentaram maior inibição contra Gram-negativos. A ação inibitória registrada para os extratos da Q. parviflora Mart. pode estar relacionada a sua composição fitoquímica, pois apresenta vários metabolitos secundários com atividade antimicrobiana. Porém, são necessários estudos complementares para comprovação da presença dos compostos secundários capazes de atuar na inibição de micro-organismos, além de testes como a microdiluição em caldo para auxiliar na confirmação da ação inibitória dos compostos presentes na Q. parviflora Mart.Palavras-chave: Antibiótico. Cerrado. Extratos Vegetais.AbstractAntimicrobial resistance to pathogens is mainly due to the irrational use of antibiotics and constitutes a threat to the control of infectious diseases. Studies of the antibacterial activities of plant extracts can provide alternatives for the antimicrobial treatment and, therefore, has aroused interest by the investigation for the potential of the Brazilian flora. It was aimed to analyze the possible antibacterial activity of the species Qualea parviflora Mart. The tests were carried out by diffusion in disks previously sensitized with extracts obtained by stem maceration and leaves at concentrations of 50 and 100% (99.5 °GL ethanol as extractor). Tests were performed for Gram-positive strains (Staphylococcus aureus and Streptococcus pyogenes) and Gram-negative (Escherichia coli). The sensitized discs were placed in the culture plates and incubated at 37 °C / 24 hours. Inhibition halos were analyzed by visual reading. Concentrated (100%) extracts of bark and leaf showed inhibition against Gram-positive and Gram-negative, being the most effective leaf extract. At 50% concentration the inhibition was only observed with leaf maceration. Extracts from leaf maceration showed greater inhibition against Gram negative. The inhibitory action recorded for the extracts of Q. parviflora Mart. may be related to its phytochemical composition, since it presents several secondary metabolites with antimicrobial activity. However, further studies are necessary to prove the presence of secondary compounds capable to act in inhibition of microorganisms, as well as testing broth microdilution to assist in confirming the inhibitory action of the compounds present in Q. parviflora Mart. Keywords: Antibiotic. Cerrado. Plant Extracts. AbstractAntimicrobial resistance to pathogens is mainly due to the irrational use of antibiotics and constitutes a threat to the control of infectious diseases. Studies of the antibacterial activities of plant extracts can provide alternatives for the antimicrobial treatment and, therefore, has aroused interest by the investigation for the potential of the Brazilian flora. It was aimed to analyze the possible antibacterial activity of the species Qualea parviflora Mart. The tests were carried out by diffusion in disks previously sensitized with extracts obtained by stem maceration and leaves at concentrations of 50 and 100% (99.5 °GL ethanol as extractor). Tests were performed for Gram-positive strains (Staphylococcus aureus and Streptococcus pyogenes) and Gram-negative (Escherichia coli). The sensitized discs were placed in the culture plates and incubated at 37 °C / 24 hours. Inhibition halos were analyzed by visual reading. Concentrated (100%) extracts of bark and leaf showed inhibition against Gram-positive and Gram-negative, being the most effective leaf extract. At 50% concentration the inhibition was only observed with leaf maceration. Extracts from leaf maceration showed greater inhibition against Gram negative. The inhibitory action recorded for the extracts of Q. parviflora Mart. may be related to its phytochemical composition, since it presents several secondary metabolites with antimicrobial activity. However, further studies are necessary to prove the presence of secondary compounds capable to act in inhibition of microorganisms, as well as testing broth microdilution to assist in confirming the inhibitory action of the compounds present in Q. parviflora Mart. Keywords: Antibiotic. Cerrado. Plant Extracts.