The effect of intestinal flora changes on the pharmacokinetics of astragaloside Ⅳ in rats with type 2 diabetes mellitus was explored in this study. The rat model in preliminary experiment was established by high-sugar and high-fat diet combined with the intraperitoneal injection of low-dose streptozotocin(STZ). Rats were divided into model group, astragaloside Ⅳ group, berberine group and combination group(five rats in each group). After two weeks of gavage, the rats' feces was taken for 16 S rRNA sequencing of intestinal flora. Pharmacokinetic experiments were performed on astragaloside Ⅳ in the four groups one day after the preliminary experiment. Plasma samples were precipitated in methanol with ginsenoside Rb_1 as an internal standard, and the plasma concentrations of astragaloside Ⅳ at different time points were determined by UPLC-MS/MS. The chromatographic separation was performed on a Waters Acquity UPLC BEH-C_(18) column(2.1 mm×100 mm, 1.7 μm) via gradient elution. The mobile phase was acetonitrile(A) and 5 mmol·L~(-1) ammonium formate solution with 0.2% formic acid(B). The flow rate was 0.4 mL·min~(-1), the injection volume 5 μL and the column temperature 40 ℃. The mass spectrometry was carried out with electrospray ionization source(ESI) in multiple reaction monitoring and positive ion modes. The specificity, linearity range, accuracy, precision, stability and dilution effect of the method all met the requirements for the determination of astragaloside Ⅳ in plasma. Plasma concentration-time curves were plotted and relevant pharmacokinetic parameters were calculated by DAS 3.2.8. The results showed that the concentration of absorbed astragaloside Ⅳ increased within 0-3.95 h and began to decline since 3.95 h. After 36 h, the metabolism was complete. The area under the plasma concentration-time curve(AUC_(0-t)) and the peak concentration(C_(max)) of astragaloside Ⅳ were increased in the three administration groups compared with the model group, but without significant difference, which suggested that the pharmacokinetic characteristics of saponin components would not necessarily change after the drug-induced alteration of intestinal flora.
Keywords: UPLC-MS/MS; astragaloside Ⅳ; berberine; pharmacokinetics.