Brazilian phytopharmaceuticals--evaluation against hospital bacteria.

Pharmaceutical companies have demonstrated renewed interest in investigating higher plants as sources for new lead structures and also for the development of standardized phytotherapeutic agents of proven efficacy, safety and quality. This work analysed three commercial phytopharmaceuticals against multi-resistant bacteria of medical importance, including methicillin-resistant Staphylococcus aureus isolates from the Brazilian endemic clone. From the phytopharmaceuticals assayed, plants from the products 'Astmoflora' and 'Kókolos' were considered active, while plants from 'Uva do Mato' were not active in the tested concentrations, which ranged from 62.5 to 500 microg/mL. Among fractions of Aristolochia cymbifera and Myroxylon balsamum, the hexane extracts showed the best results against Staphylococcus spp. and Pseudomonas aeruginosa. These fractions showed growth inhibition of all methicillin-sensitive and -resistant Staphylococcus aureus strains and the majority of the Pseudomonas aeruginosa strains at a concentration of 500 microg/mL. Bioassay-guided fractionation of hexane extracts of Aristolochia cymbifera and Myroxylon balsamum led to the identification of the diterpene 2-oxo-populifolic acid and of the chalcone isoliquiritigenin, respectively, as antimicrobial compounds.