Resumo

Introduction: The search for biologically active compounds for therapeutic purposes in plants has enriched the therapeutic options with new antimicrobial, antitumor drugs among others. In order to seek for new drugs against multi-resistant bacteria, this study aims to scientifically confirm the activity of extracts from leaves of Bauhinia rufa, Erythroxylum daphynites and Eugenia dysenterica as an antimicrobial. These species are widely spread in the Brazil Central Cerrado and can be found at Distrito Federal area. Material and Method: Hexane and ethanol extracts from B. rufa and E. daphynites were obtained by maceration and solvents were eliminated by rota-evaporation at temperature under 40^oC; the aqueous extract from E. dysenterica was obtained by infusion, followed for lyophylization. Ethanol and aqueous crude extracts were partitioned on immiscible solvents. For antimicrobial activity were evaluated crude extracts and fractions. The used strains were Staphylococcus aureus (ATCC 25923) and Escherichia coli (ATCC 25922). The Minimal Inhibition Concentration (MIC) was determined according to the disc-diffusion method by NCCLS, 2003. Results/Discussion: The crude extracts and fractions of B. rufa, E. daphynites and E. dysenterica were poorly active against E. coli, while the crude ethanol and aqueous extracts of E. daphynites, the ethyl acetate fractions of both E. daphynites and B. rufa and the crude aqueous extract of E. dysenterica and its methanol and acetone fractions showed better inhibitory results, ranging from a 7 to 15 mm inhibition zone (minimal concentration in disc of 62µg/20µL for all extracts studied) against S. aureus. The crude extracts and both fractions were analyzed using HPLC-DAD The ethyl acetate fraction of B. rufa showed the presence of rutin and other quercetin derivatives The ethyl acetate fraction of E. daphynites showed the presence of catechin and epicatechin and their derivatives; acetato and methanol fractions of E. dysenterica presented flavonoids, catechins and derivatives. Conclusion: The crude ethanol and aqueous extracts of E. daphynites, the ethyl acetate fractions of both E. daphynites and B. rufa and the crude aqueous extract of E. dysenterica and its fractions showed interesting antimicrobial activity against S. aureus. As far we know, it was the first time E. daphynites and B. rufa were evaluated about antimicrobial activity. Acknowledgements: This research was supported by CNPq, CAPES and FAPDF.