Liver-protective activities of aucubin derived from traditional oriental medicine.

The iridoid glycosides including aucubin (AU), catalpol (CA), swertimarin (SW), and gardenoside (GA) are frequently found as natural constituents of many traditional oriental medicinal plants including Chinese herbs. Among these iridoid glycosides, AU was systematically studied for its potent liver-protective activities using experimental systems of hepatic damage. AU showed high liver-protective activity against carbon tetrachloride-induced hepatic damage in mice. Also AU showed significant protective activity against alpha-amanitin-induced hepatic damage in mice, and it prevented a depression of liver RNA biosynthesis caused by alpha-amanitin administration. Potent antidotal effects on mushroom poisoning in beagle dogs ingested with aqueous extract of Amanita virosa was observed; beagle dogs completely survived, even when AU administration was withheld for half an hour after mushroom poisoning. In addition, AU was found to suppress hepatitis B viral DNA replication in vitro. Conversion of AU to its aglycone form appeared to be a prerequisite step for an exhibition of such antiviral activity.