Degradation of Paeoniflorin in Guanxin II Prescription by Intestinal Bacteria

OBJECTIVE To develop a HPLC method for investigating the degradation characteristics and possible covariates of paeoniflorin when being incubated with rat feces.METHODS Paeoniflorin content was measured by HPLC.The separation was performed on a C18 reverse phase column with the mobile phase consisting of CH3CN-H2O at the flow rate of 1.0 mL·min-1.The detection wavelength was at 230 nm.Four different types of paeoniflorin solution were prepared and incubated with rat feces for different times.The degradation profiles were estimated with a nonlinear mixed effect modeling program.RESULTS The HPLC method developed was satisfactory for the investigation of paeoniflorin degradation kinetics in rat feces.The liearity was in the range of 0.787 5~39.38 mg·L-1.Both intra-day and inter-day variability were less than 5%.The degradation of paeoniflorin took place about one hour after the start of incubation.The degradation time delay,the rate constant,as well as the style of degradation was influenced by the types of paeoniflorin solution.CONCLUSION The change of paeoniflorin concentration in most of the four types of solutions can be described by a First-order kinetic model,except for the group of Guanxin II where the change of paeoniflorin's concentration is fitted with a zero-order kinetic model.