Identification of the metabolites of biologically active xanthones isolated from Halenia elliptica D

Metabolism study has been carried out on l-hydroxy-2,3,5-trimethoxyxanthone (HM-1) and l-hydroxy-2,3,4,7-tetramethoxyxanthone (HM-2), which are two biologically active ingredients isolated from the Tibetan herb, Halenia elliptica D. Don., in rat liver microsomes in vitro. A method of high performance liquid chromatography coupled to ion trap time-of-flight mass spectrometry (LCMSn-ESI-IT-TOF) was applied to analyze metabolites of HM-1 and HM-2 on line, and five metabolites were identified containing l,5-dihydroxy-2,3-dimethoxyxanthone (HM-5), l,7-dihydroxy-2,3,4-trimethoxyxanthone (HM-9), 1,4, 7-trihydroxy-2,3-dimethoxyxanthone (HM-10), l,4-dihydroxy-2,3,7-trimethoxyxanthone (HM-11) and l,2-dihydroxy-3,4,7-trimethoxyxanthone (HM-12). Among these metabolites, HM-9, HM-11, and HM-12 were isomers mutually. The results indicated that HM-1 and HM-2 occurred Phase I metabolic reaction of demethylation in rat microsomes in vitro.