2004 Volume 27 Issue 5 Pages 744-747
In order to further determine the nature of structure–activity relationship on the cytotoxicities of saponins with 1→2 and 1→3 linkages of disaccharides, we isolated guaianin N, collinsonidin, kalopanaxsaponin A and hederoside D2 as disaccharides, and patrinia glycoside B-II as a trisaccharide, from the n-BuOH extract of Akebia quinata (Lardizabalaceae). Complete acid hydrolysis of the extract afforded oleanolic acid (1) and hederagenin (2). By sulforhodamine B (SRB) assay, kalopanaxsaponin A containing an α-L-rhap-(1→2)-α-L-arap moiety exhibited distinctly higher cytotoxicity (IC50 1.8—2.7 μg/ml) against all of the tested cell lines than the other saponins (IC50, 4—8 μg/ml). These results suggest that the α-L-rhap-(1→2)-α-L-arap moiety has a unique structural significance in terms of its cell biochemistry, compared to those oleanane glycosides with other sugar linkages. On the other hand, kalopanaxsaponin A exhibited a significant inhibitory effect on nitric oxide production by lipopolysaccharide (LPS)-activated macrophage 264.7, whereas other saponins had weaker activities.