Study of the phase I and phase II metabolism of a mixture containing multiple tanshinones using liquid chromatography/tandem mass spectrometry

Metabolism of a mixture containing four dominant components in lipid solubles of Danshen was studied both in vitro and in vivo. The parent compounds and their metabolites were simultaneously detected by using liquid chromatography coupled with ion trap mass spectrometry. The results indicated that oxidation was the major pathway in phase I metabolism. O-Glucuronidation of the hydroxylated tanshinones was identified in the rat urine samples collected after the oral administration of the tanshinone components. The metabolic rates obtained from the in vitro metabolism study of each individual component were significantly different from those obtained from the incubation study of the four components in a cassette. Metabolite identification showed that tanshinone IIA and tanshinone I were the major metabolites of cryptotanshinone and dihydrotanshinone I, respectively. The obtained results demonstrated the metabolic change between the active components in Danshen and suggested the need to study the multiple components or even the extract from the herbal medicines.