Profiling the metabolic difference of seven tanshinones using high-performance liquid chromatography/multi-stage mass...

Tanshinones are a class of bioactive constituents in the roots of Salvia miltiorrhiza named Dan-Shen in Chinese, which possess diverse pharmacological activities. In this study, we employed a sensitive high-performance liquid chromatography/multi-stage mass spectrometry (HPLC/MS(n)) method with data-dependent acquisition and a dynamic exclusion program for the identification of phase I metabolites of seven tanshinones in rat bile after intravenous administration. These seven tanshinones are tanshinone IIA, sodium tanshinone IIA sulfonate (abbreviated as STS, a water-soluble derivate of tanshinone IIA), cryptotanshinone, 15,16-dihydrotanshinone I, tanshinone IIB, przewaquinone A and tanshinone I. Altogether 33 metabolites underwent monohydroxylation, dihydroxylation, dehydrogenation, D-ring hydrolysis or oxidation reactions in the C-4 or C-15 side chain which were characterized by analyzing the LC/MS(n) data. Different metabolic reactions for tanshinones were dependent on the degree of saturation and the substituent group in the skeleton. Dehydrogenation was the major metabolic modification for cryptotanshinone with saturated A and D rings. 15,16-Dihydrotanshinone I containing a saturated D ring was mainly metabolized through D-ring hydrolysis. For tanshinone IIA, possessing a saturated A ring, hydroxylation was the major metabolic pathway. When there was hydroxyl group substitution in the C-17 or C-18 position, such as przewaquinone A and tanshinone IIB, or sulfonic group substitution in the C-16 position, such as STS, higher metabolic stability than that of tanshinone IIA was shown and only trace metabolites were generated. Oxidation in the C-4 or C-15 side chain was a characteristic reaction for tanshinone IIA and hydroxylated tanshinone IIA. For tanshinone I, bearing unsaturated A and D rings simultaneously, no metabolites were detected.