Asterlingulatosides C and D, cytotoxic triterpenoid saponins from Aster lingulatus

A further investigation of Aster lingulatus has led to the isolation of two additional novel triterpene saponins, asterlingulatoside C [3-O-beta-D-glucopyranosyl-3 beta,16 alpha-dihydroxyolean-12-en-28-oic acid 28-O-beta-D-xylopyranosyl-(1 --> 4)-alpha-L-rhamnopyranosyl-(1 --> 2)-alpha-L-arabinopyranoside] (1) and asterlingulatoside D [3-O-beta-D-glucopyranasyl-3 beta,16 alpha-dihydroxyolean-12-en-28-oic acid 28-O-beta-D-xylopyranosyl-(1 --> 3)-beta-D-xylopyranosyl-(1 --> 4)-alpha-L-rhamnopyranosyl-(1 --> 2)-alpha-L-arabinopyranoside] (2). Elucidation of the structures of 1 and 2 was mainly based on FABMS and 1D and 2D homonuclear and heteronuclear NMR techniques. Compounds 1 and 2 showed good inhibitory activity against DNA synthesis in human leukemia HL-60 cells with IC50 values of 8.8 and 6.1 mu M, respectively.