Antimicrobial Activity and Rates of Tannins in Stryphnodendron adstringens Mart. Accessions Collected in the Brazilian Cerrado

摘要

Inner bark extracts of Stryphnodendron adstringens, a leguminous tree species known as Barbatim?o, are often incorporated to phytotherapic formulations due to their antimicrobial and healing activities. In this study, extracts from S. adstringens accessions collected in 12 distinct locations were investigated in order to determine the rates of tannins in inner barks and to validate S. adstringens antibacterial and antifungal effectiveness. Yields of tannins were quantified by colorimetric assay following methodology described in the Brazilian Pharmacopoeia and the antimicrobial activity was determined by microdilution technique proposed by the National Committee for Clinical Laboratory Standards using S. adstringens hydroalcoholic and aqueous extracts and semi-purified fractions. Investigated extracts did not present significant antibacterial activity though aqueous extracts exhibited antifungal effect against both Trichophyton rubrum mutant and clinical strains (MIC 156 μg/mL). A positive correlation between tannin concentration and antifungal activity was observed and the accessions collected in Delfinópolis (MG) were considered elite.