CYTOTOXIC POLYKETIDES FROM ANNONA-DENSICOMA (ANNONACEAE) - 10,13-TRANS-13,14-ERYTHRO-DENSICOMACIN, 10,13-TRANS-13,14-THREO-DENSICOMACIN, AND 8-HYDROXYANNONACIN

Three new linear polyketides, 10,13-trans-13,14-erythro-densicomacin (1), 10,13-trans-13,14-threo-densicomacin (2), and 8-hydroxyannonacin (3), and a known polyketide goniothalamicin were isolated from the stem bark of the Peruvian plant Annona densicoma Mart (Annonaceae). Their structures were elucidated on the basis of UV, IR, H-1 and C-13 NMR, and mass spectrometry data of the natural compounds and their derivatives. These polyketides are cytotoxic against human tumor cells in culture. In particular, densicomacins (I and 2) were significantly active against the lung carcinoma (A-549) and the colon adenocarcinoma (HT-29) cell lines with ED50 at 4 X 10(-4) and 1 x 10(-5) mug/mL, respectively.