Plant anticancer agents, XLVIII. 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 constituents being based on 1H-1H COSY, 1H-13C 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.