Semi-synthesis of Twelve Known 20Z/E Pseudo-Ginsenosides and Their Comparative Study of Antioxidative Activity in Free Radical Induced Hemolysis of Rabbit Erythrocytes.

Twelve pseudo-ginsenosides were synthesized under a mild condition, via a simple three-step called acetylation, elimination-addition and saponification. The inhibitory effects of these twelve pseudo-ginsenosides were screened on the hemolysis of rabbit erythrocytes caused by 2,2'-azobis (2-amidinopropane hydrochloride) (AAPH). It was found that the IC50 values followed the sequence of (20Z) pseudo-protopanaxatriol (pseudo-PPT)<(20Z) pseudo-protopanaxadiol (pseudo-PPD)<(20Z) pseudo-Rh2<(20E) pseudo-PPT<(20E) pseudo-PPD<(20E) pseudo-Rh2<(20Z) pseudo-Rg2<(20E) pseudo-Rg2<Rb1<(20Z) pseudo-Rh1<Rg2<(20E) pseudo-Rh1. These compounds can be divided into three groups: accelerate the hemolysis group (7, 8), weak group (2, 11, 12) and strong group (others). Moreover, we also find that most of the Z configuration has better antioxidative activity than E configuration and the number and type of sugar moieties to the ring of triterpene dammarane influence the antioxidative activity.