Cytotoxic tetraoxygenated xanthones from the bark of Garcinia schomburgkiana

► Chemical constituents of the bark of Garcinia schomburgkiana. ► Isolation and structure elucidation of eight compounds. ► Two new tetraoxygenated xanthones, 6-O-demethyloliverixanthone and schomburgxanthone. ► Cytotoxicity against HeLa cells using an MTT assay. ► Fuscaxanthone B and cowanin possessed remarkable activity (IC50 2.4-2.7 μg/ml).