Soulaxanthone, a new xanthone derivative from .

In search for new metabolites from the stem bark of and , led to the isolation of a new xanthone, soulaxanthone (), along with four other known metabolites, euxanthone (), calopolyanolide E (), calanolide E () and friedelin (). The structures of these compounds were identified and elucidated using spectroscopic techniques such as H NMR,C NMR, COSY, DEPT, HSQC, HMBC, MS and FTIR. The antibacterial activities of compounds -, as well as the extracts, were tested against five bacterial strains. Soulaxanthone () exhibited moderate activity against with an MIC value of 25 µg/mL. Hexane (non-polar) extract from both plants exhibited moderate activity against (MIC = 250 µg/mL). Calopolyanolide E () and friedelin () showed bactericidal activity against (MBC = 50 µg/mL), thus the compounds have the potential to serve as a new lead for developing effective antibacterial medication.