香加皮提取物杠柳毒苷水解动力学研究

目的:明确香加皮提取物中杠柳毒苷的水解动力学特征。方法:采用HPLC-UV考察杠柳毒苷在不同的初始浓度(10～100μg/mL),pH值在1.2～8.7之间和温度(50～70℃)条件下的水解过程,并运用HPLC-ESI-TOF/MS对其水解产物进行鉴定。结果:在pH=2,T=50℃条件下杠柳毒苷水解的速率常数Kobs不受药物影响;温度对反应速率常数的影响遵循阿伦尼乌斯方程;在25℃条件下杠柳毒苷在pH=4的条件下较为稳定(pH=4时,半衰期为56.62天);采用液质联用对其水解产物进行定性分析,确定水解产物为杠柳苷元。结论:杠柳毒苷的水解过程符合一级动力学,杠柳毒苷的初始浓度对水解动力学参数没有影响,水解速率与温度和pH相关性较大。

Study on Hydrolysis Kinetics of Periplocin Extracted from Cortex periplocae

Objective:To investigate the hydrolysis kinetics of periplocin extracted from Cortex periplocae.Method:The hydrolytic kinetics in aqueous buffers of periplocin extracted from Cortex periplocae was detected using stability-indicating HPLC with UV detection and ultra high performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry(UHPLC-ESI-TOF/MS).The hydrolysis of periplocin was investigated in aqueous buffers under a variety of initial concentration(10~100μg/mL),pH value(pH=1.2~8.7)and temperatures(50~70℃).And then the hydrolytic degradation product was separated and identified by UHPLC-ESI-TOF/MS.Result:The rate constant of hydrolysis had no change under different initial concentration in the condition of pH=2,T=50℃.The logKobs-pH profile showed the optimal stability range at pH>4 and the half-life at 25℃ was predicted to be 56.62 days in the solution of pH=4.0.The rate constant of overall hydrolysis as a function of temperature under the given conditions obeyed the Arrhenius equation.Conclusion:The results of the experiment showed that the hydrolysis followed pseudo-first-order kinetics and the initial concentration of periplocin has no effect on the degradation rate.Then the temperature and pH value can change the process of the hydrolysis of periplocin.