Karwinaphthopyranones from the fruits of Karwinskia parvifolia and their cytotoxic activities

The new 2-acetyl-8-methoxynaphthol (1) and five new "dimeric" napthopyranones, karwinaphthopyranones A1 and A2 (2 and 3) and karwinaphthopyranones B1-B3 (4-6), possessing a methoxy group at C-5', were isolated together with four Other known compounds from the dried fruits of Karwinskia parvifolia. The structures of compounds 2-6 were determined by spectroscopic data interpretation. Cell Culture assays showed that some of these compounds possess antiproliferative activities in representative human Cancer cell lines, with half-maximal growth inhibitory concentrations in the micromolar range.