Antimicrobial activity and bioactive compounds of portuguese wild edible mushrooms methanolic extracts

The antimicrobial properties of phenolic extracts of Portuguese wild edible mushroom species (Lactarius deliciosus, Sarcodon imbricatus and Tricholoma portentosum) against pathogens were investigated. The minimal inhibitory concentrations (MICs) were evaluated for the entire mushroom, the cap and the stipe, separately; the portion of the mushroom used proved to be influenced in the results obtained, which are directly correlated with the content of total phenols and flavonoids in the extracts. The growth of Grampositive bacteria (Bacillus cereus, B. subtilis,) was well inhibited by these mushrooms, while Escherichia coli (Gramnegative bacteria) was resistant. The study on the antifungal effect of these mushrooms revealed that Candida albicans and Cryptococcus neoformans were differently inhibited for the mushrooms used

Antimicrobial activity and rutin identification of honey produced by the stingless bee Melipona compressipes manaosensis and commercial honey

Background: Honey has been identified as a potential alternative to the widespread use of antibiotics, which are of significant concern considering the emergence of resistant bacteria. In this context, this study aimed to evaluate the antimicrobial activity of honey samples produced by a stingless bee species and by Apis sp. against pathogenic bacteria, as well as to identify the presence of phenolic compounds.Methods: Honey samples from the stingless bee M. compressipes manaosensis were collected twice, during the dry and rainy seasons. Three commercial honey samples from Apis sp. were also included in this study. Two different assays were performed to evaluate the antibacterial potential of the honey samples: agar-well diffusion and broth macrodilution. Liquid-liquid extraction was used to assess phenolic compounds from honey. HPLC analysis was performed in order to identify rutin and apigenin on honey samples. Chromatograms were recorded at 340 and 290 nm.Results: Two honey samples were identified as having the highest antimicrobial activity using the agar diffusion method. Honey produced by Melipona compressipes manaosensis inhibited the growth of Staphylococcus aureus, Escherichia coli (0157: H7), Proteus vulgaris, Shigella sonnei and Klebsiella sp. A sample of honey produced by Apis sp. also inhibited the growth of Salmonella paratyphi. The macrodilution technique presented greater sensitivity for the antibacterial testing, since all honey samples showed activity. Flavonoid rutin was identified in the honey sample produced by the stingless bee.Conclusions: Honey samples tested in this work showed antibacterial activity against Gram-positive and Gram-negative bacteria. The results reported herein highlight the potential of using honey to control bacterial growth. © 2013 Pimentel et al.; licensee BioMed Central Ltd

Interactions of resveratrol with other phenolics and activity against food‐borne pathogens

The aim of this study was to investigate the antibacterial activity of individual phenolics and their binary mixtures with resveratrol against selected food‐borne pathogens. The antibacterial activity was quantified using the broth microdilution method by the determination of minimal inhibitory concentrations (MICs). Interactions between compounds in the binary phenolic mixtures were determined by calculating the fractional inhibitory concentration index (FICI). The influence of the number of OH groups in the phenols’ structure on their antibacterial activity was assessed by principal component analysis (PCA). The most effective compounds were flavone luteolin and flavonol rutin, while the weakest antimicrobial activity was observed for phenolic acid and flavan‐3‐ols (catechin and epicatechin). The synergistic effect (FICI ≤0.5) of equimolar mixture of resveratrol with kaempferol was confirmed against Staphylococcus aureus, Bacillus cereus, and Escherichia coli, while the mixture of rutin with resveratrol proved synergistic only against S. aureus. The increasing concentrations of resveratrol in the mixtures with kaempferol and rutin resulted in a loss of synergism which indicates that only selected phenolic mixtures, with optimal concentrations of their individual components, result in synergistic antibacterial activity. We did not find an association between total number of OH groups and antibacterial activity of either individual phenolics or their mixtures

Atividade antimicrobiana de Schinus terebenthifolius Raddi Antimicrobial activity of Schinus terebenthifolius Raddi

Objetivou-se com este trabalho analisar a atividade antimicrobiana de extratos aquoso e alcoólico obtidos de frutos da Schinus terebenthifolius ou aroeira-vermelha, diretamente ligados à quantidade de compostos fenólicos existentes nesses extratos. Pelos testes, verificou-se que o extrato alcoólico apresentou efeito inibitório sobre o crescimento de Staphylococcus aureus e Bacillus cereus, já o extrato aquoso não apresentou efeito inibitório sobre os crescimento dos microrganismos testados. O extrato alcoólico mostrou-se com quantidade significativa da flavona apigenina, além de ácido elágico, ao passo que no extrato aquoso foi observada a presença da flavanona naringina.<br>This research analyzed the antimicrobial activity of aqueous and alcoholic extracts obtained from Schinus terebenthifolius fruits or aroeira-vermelha, directly linked to the amount of phenolics compouds existent in these extracts. The tests showed that the alcoholic extract presented an inibitory effect to the growth of Staphylococcus aureus and Bacillus cereus, and the aqueous extract didn't present inibitory effect to the growth of the tested microorganisms. The alcoholic extract was shown with a significant amount of the flavone apigenin, besides ellagic acid and siringic acid, while in the aqueous extract was observed the flavanone naringine