Atividade antimicrobiana, antioxidante e composição química de espécies do gênero Blechnum da Mata Atlântica baiana

Abstract

In last years, the increasing of the incidence of oxidative diseases and infections caused by multi-resistant pathogens to drugs has encouraged the study of natural products, especially those focused on research about phytochemical and therapeutic aspects on non-knowing plants, like the ferns. The aim of this study was to investigate the antimicrobial and antioxidant activity, the total amount of phenolic compounds and flavonoids from methanolic extracts obtained from the subterranean and aerial parts of species of the genus Blechnum from Atlantic Forest of Bahia - B. occidentale L. and B.serrulatum Rich. In the investigation of the antimicrobial activity of crude extracts the minimum inhibitory concentration (MIC) and minimum bactericidal/fungicide concentration (MBC/MFC) was determined. The micro-organisms tested were: Escherichia coli CCMB 261, Pseudomonas aeruginosa CCMB 268, Bacillus cereus CCMB 282, Staphylococcus aureus CCMB 262, Candida albicans CCMB 286 and Candida parapsilosis CCMB 288. In the antioxidant assay was used the scavenging stable radical 2,2-diphenyl-1-picryl-hydrazyl (DPPH) methodology. The levels of total phenolic compounds and flavonoids in the extracts were obtained by spectrophotometric methods using, in the first case, the Folin-Ciocalteau reagent and in the second, aluminum chloride. In the antimicrobial assay, all extracts inhibited the growth of, at least, four microrganisms tested, highlighting the extract of the aerial part of B. serrulatum, which inhibited five microrganisms and had the lowest MIC and MBC / MFC. In the antioxidant assay also the most active extract was one obtained from the aerial parts of B. serrulatum. All extracts showed phenolic compounds and flavonoids. With the extract of the aerial part of B. serrulatum, the percentage of antioxidant activity was proportional to the total phenolic quantity, but it was not observed the same association with the flavonoids quantity. The results of this study indicate the species of this study as possible targets in bioprospection of new antimicrobials and antioxidants agents.