METALLOTHIONEIN INDUCTION AND HEPATOPROTECTION BY ECHINOSIDE-A AND SAKURASO-SAPONIN

Metallothionein-inducing activities of 11 saponins were investigated i n mice. Of the saponins investigated, echinoside A and sakuraso-saponi n were highly effective. Sakuraso-saponin showed dose-dependent and ti me-dependent induction of hepatic metallothionein. The isoforms of the induced metallothionein in the liver were determined to be metallothi onein 1 and 2. Induction of metallothionein was observed specifically in the liver and heart. Echinoside A showed similar effects to sakuras o-saponin except that no induction was observed in the heart. Pretreat ment of mice with these saponins blocked CCl4-induced hepatic injury, such as the elevation of plasma transaminase activity and centrilobula r necrosis in the liver. CCl4-induced elevation of lipid peroxide leve l in the liver was also blocked by injection of sakuraso-saponin, The hepatoprotective activities of the saponins found in this study may ha ve been due to their MT-inducing activity. (C) 1997 by John Wiley & So ns, Ltd.