The herbal formula Yin-Chen-Hao-Tang has been reported to have anti-fibrosis properties. The aim of this study was to reveal the pharmacokinetic characteristics of bioactive compounds in this herbal formula. A new high-performance liquid chromatography-tandem mass spectrometry method was developed and validated for simultaneous determination of scoparone, geniposide and rhein in rat plasma. A pharmaceutical herbal powder was administered to rats at doses of 1 g/kg and 3 g/kg orally. The method showed excellent linearity (r² > 0.999) and validation was successfully conducted for the pharmacokinetic study. The results show that the Cmax values and areas under the curve of scoparone, geniposide and rhein were higher and not proportional to the dose in rat plasma, while the Tmax and half-life values were consistent in the group that received 1 g/kg. The clearance of the higher dose (3 g/kg) did not decrease proportionally to that of the low dose. The results showed the nonlinear pharmacokinetic properties of scoparone, geniposide and rhein in Yin-Chen-Hao-Tang that suggested possible accumulation of bioactive compounds through oral administration. This pharmacokinetic study reveals that an increased dose of this herbal formula would largely increase the maximum concentration and bioavailability of scoparone, geniposide and rhein.
Keywords: Yin-Chen-Hao-Tang; geniposide; herbal medicine; rhein; scoparone; tandem mass spectrometry.