The structure-hemolysis relationship of oleanolic acid derivatives and inhibition of the saponin-induced hemolysis with sapogenins.

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Abstract
Chikusetsusaponin IV and V, whose genin is oleanolic acid, exhibited weak hemolytic activities on human erythrocytes. Removal of glucose residue at position 28 of chikusetsusaponin V by partial hydrolysis increased the activity more than 30-fold. Methylation of the carboxyl group at position 28 increased the activity further by .apprx. 10-fold, showing HD50 [median hemolytic dose] value of 3.77 .mu.M. Removal of the sugar chain at position 3 of chikusetsusaponin V by partial hydrolysis completely lost the activity. The sugar chain at position 3 of oleanolic acid is essential but that at position 28 is pernicious for the activity. The cytolytic agents, whose target was regarded as membrane cholesterol, were inactivated by cholesterol and by sapogenins such as oleanolic acid, gitogenin and hederagenin. Among saponins tested, akebia saponin B and C were inactivated by cholesterol, but not by the genins, probably because their affinities for the genins are too low to form complexes.