Phytochemical Study and Antimicrobial Activity Evaluation of Talauma ovata. Petroleum ether and ethanol extracts of trunk bark and leaves from Talauma ovata St. Hil. (Magnoliaceae) were submitted to chromatographic separation. This procedure furnished the sesquiterpene lactones costunolide and parthenolide and the aporphine alkaloids liriodenine, lanuginosine, dicentrinone, O-methylmoschatoline and N-acetylxylopine. Crude extracts, fractions from sequential partition with solvents and isolated compounds were screened against 15 Gram-positive bacteria, 3 Grain-negative bacteria and 3 yeasts, using the agar well-diffusion technique. The most activity was detected in the fraction in dichloromethane from ethanol extract of trunk bark, which was active against Gram-positive bacteria, but not against Gram-negative bacteria or fungi. Parthenolide and O-methylmoschatoline showed good and specific activity against several strains of Staphylococcus aureus, with minimum inhibitory concentration (MIC) varying from 100 to 25 mu g/mL. The alkaloid N-acetylxylopine exhibited moderate activity against Candida albicans (MIC = 250 mu g/mL). This is the first report of liriodenine, lanuginosine, dicentrinone and O-methylmoschatoline in T. ovata.282270274