PLANT ANTICANCER AGENTS .48. NEW CYTOTOXIC FLAVONOIDS FROM MUNTINGIA-CALABURA ROOTS

From a cytotoxic Et2O-soluble extract of Muntingia calabura roots, twelve new flavonoids were isolated, constituting seven flavans 1-7, three flavones 8, 10, and 12, and two biflavans 9 and 11. The structures of compounds 1-12 were established by the interpretation of spectral data, with the nmr assignments of these constitutents being based on H-1-H-1 COSY, H-1-C-13 HETCOR, and selective INEPT experiments. This is the first report of the occurrence of 7,8-di-O-substituted flavans, biflavans, and flavones. Most of the isolates demonstrated cytotoxic activity when tested against cultured P-388 cells, with the flavans being more active than the flavones. Furthermore, certain of these structurally related flavonoids exhibited somewhat selective activities when evaluated with a number of human cancer cell lines.