Comparative pharmacokinetics of major bioactive components from Puerariae Radix-Gastrodiae Rhizome extracts and their intestinal absorption in rats

Puerariae Radix (PR) and Gastrodiae Rhizome (GR) is frequently used in traditional herbal formulas to treat cardio-cerebral vascular diseases due to their synergistic effects. In this study, to elucidate the action mechanism of PR-GR in vivo, a simple and reliable ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method for simultaneous determination of nine bioactive ingredients from PR-GR in plasma was developed and applied to a comparative pharmacokinetic study following oral administration of PR, GR, and PR-GR aqueous extracts in rats. The effect of GR on the absorption of components of PR was also investigated by single-pass intestinal perfusion study. Results showed that comparing to the single herbs, PR-GR extract significantly increased the systemic exposure of puerarin, 3′-hydroxypuerarin, 3′-methoxypuerarin, 6″-O-xylosylpuerarin, daidzin, genistein, and gastrodin. Moreover, the intestinal absorption of puerarin and daidzin could be improved by GR extract and inhibitors of P-glycoprotein and multidrug resistanceassociated protein 2, respectively. These results indicate that the combination of PR and GR increases the levels of their bioactive ingredients exposed in the blood, and GR increases the absorption of ingredients of PR may by inhibition of the efflux mediated by P-glycoprotein and multidrug resistanceassociated protein 2. This is the first report for the pharmacokinetics and intestinal absorption of PR-GR, which may explain their synergetic effects in the treatment of circulatory systematic diseases and provide a meaningful insight for their clinical applications.