Estudo químico e avaliação da atividade antimicrobiana da espécie vegetal Croton floribundus (Euphorbiaceae)

Abstract

The species Croton floribundus (Euphorbiaceae), commonly know a capixingui, is usually found in Brazilian states of Sao Paulo, Rio de Janeiro, Minas Gerais and Parana. It is in folk medicine to be the active principle responsible for wound healing. Even though it is large used as folk medicine, it chemical study was not found in literature. The alkaloids are know as taxonomic markers and the diterpenes as the main constituents from Croton species. In the present work used hot (Soxhlet) and cold (maceration) extractions. The soxhlet extracts were fractionated through silica gel chromatographyyielding the kaurenoic acid (main constituent- 2%), the candol B and the glycosylated sitotesrol. The extracts from maceration were fractionated through columns of silica gel and silica gel impregnated with silver nitrate yielding the diterpenes 16 ß, 17-dihydroxy-19-kauranóic and 6-hydroxy kaur-16-en-19-ol. The acid fraction from the alcaloidic extract, after to be treated with diazomethane and fractionated through gel column, yielded the methyl ester of 16 ß-hydroxy-19-kauranoate. The compounds identification were assisted by NMR techniques as 1H, 13C, HETCOR, HMQC, COSY and by comparison to analogue compounds described in the literature. The antibacterial activity of the crude ethanolic extract, of the fractions and of the kaurenoic acid was determined by Broth microdilution method using Muller-Hinton medium for antibacterial assay. The microorganisms Staphylococcus aureus, Bacillus subtilis and Escherichia coli were tested. To run this experiment, the crude extract was partitioned with hexane, methylene chloride, ethyl acetate, buthyl alcohol and water. The hexanic fraction showed the best activity against Staphylococcus aureus and Bacillus subtilis microorganisms. The Kaurenoic acid was active against B. subtilis (6.2µg/mL).