A sensitive HPLC–MS/MS method for the simultaneous determination of anemoside B4, anemoside A3 and 23‐hydroxybetulinic acid: Application to the pharmacokinetics and liver distribution of Pulsatilla chinensis saponins

Pulsatilla chinensis saponins, the major active components in the herb, have drawn great attention as potential hepatitis B virus infection and hepatoma treatments. Here, a sensitive and accurate HPLC-MS/MS method was established for simultaneous determination of three saponins - anemoside B4, anemoside A3 and 23-hydroxybetulinic acid - in rat plasma and liver, and fully validated. The method was successfully applied to a pharmacokinetics and liver distribution study of P. chinensis saponins. Consequently, 23-hydroxybetulinic acid, with an extremely low content in the P. chinensis saponins, exhibited the highest exposure in the liver and in sites before and after hepatic disposition, namely, in the portal vein plasma and systemic plasma, followed by anemoside B4, which showed the highest content in the herb, whereas anemoside A3 displayed quite limited exposure. The hepatic first-pass effects were 71% for 23-hydroxybetulinic acid, 27% for anemoside B4 and 37% for anemoside A3, corresponding to their different extents of liver distribution. To our knowledge, this is the first investigation on the liver first-pass effect and distribution of P. chinensis saponins to date. These results also provide valuable information for the understanding of the pharmacological effect of P. chinensis saponins on liver diseases.