Liquid chromatography-tandem mass spectrometry for the identification of L-tetrahydropalmatine metabolites in Penicillium janthinellum and rats

L-Tetrahydropaimatine (L-THP) is an active alkaloid from Stephania ainiaca Diels. In order to compare the similarities and differences of microbial and mammalian metabolisms Of L-THP. the microbial transformation by Penicillium janthinellum and metabolism in rats were investigated. Biotransformation Of L-THP by Penicillium janthinellum AS 3.510 resulted in the formation of three metabolites. Their structures were identified as L-corvdalmine, L-corypalmine and 9-O-desmethyl-L-THP. respectively, by comprehensive nuclear magnetic resonance and mass spectrometry (MS) analysis. Six metabolites (M1-M6) were detected from the in vivo study in rats and three of which (L-corydalmine, L-corypalmine and 9-O-desmethyl-L-THP) were identified as the same compounds as those obtained from microbial metabolism by liquid chromatography-tandem mass spectrometry (LC-MS/ MS) analysis and comparison with reference standards obtained from microbial metabolism. The structures of the additional three metabolites were tentatively deduced as 2-O-desmethyl-L-THP and two di-O-demethylated L-THP by LC-MS/MS analysis. Time courses of microbial and rat metabolisms Of L-THP were also investigated. Copyright (c) 2005 John Wiley & Sons, Ltd.