Metabolism and pharmacokinetic study of ardipusilloside I in rats.

Ardipusilloside I, extracted from ARDISIA PUSILLA A.DC, effectively inhibits the progression of several cancers in animal models and is a potential anti-cancer drug candidate. However, the metabolism and pharmacokinetic characteristics of ardipusilloside I remain unknown. In this study, we developed a highly sensitive liquid chromatography-tandem MS method to determine the ardipusilloside I concentration in rat plasma using ginsenoside Re (whose structure is similar to ardipusilloside I) as the internal standard. After oral administration of ardipusilloside I, its four possible metabolites (M1, M2, M3, and M4, whose structures were determined by MS) were detected in the content from rat small intestine. In rat plasma, however, only M3 and M4 were detected after oral administration of ardipusilloside I. None of the metabolites were detected in plasma samples after intravenous administration of ardipusilloside I to rats. These results indicated that the metabolites, but not the drug itself, were absorbed into plasma after oral administration of ardipusilloside I to rats and that M3 and M4 may be responsible for the antitumor activity of orally administered ardipusilloside I in rat models of cancer.