女贞子中5种环烯醚萜苷类成分的降解动力学研究

Degradation kinetics of five iridoid glycosides in Ligustrum lucidum

关键词:  女贞子  稳定性  环烯醚萜苷  化学动力学

Key words:  ligustrum lucidum  stability  iridoid glycosides  chemical kinetics

摘要:

[目的] 研究女贞子中5种环烯醚萜苷类成分在不同温度、酸碱性、光照强度以及金属离子等条件下的降解动力学特征。[方法] 采用超高液相色谱（UPLC）考察不同环境下5种成分含量随时间的变化情况，以化学反应动力学方法获得一系列反应动力学参数，总结其降解规律。[结果] 5种成分在多种条件下均发生不同程度的降解，且均符合一级动力学模型；随温度升高降解速率加快；除女贞酸外其他4种成分在偏中性条件下较为稳定，酸碱性均会发生不同程度的降解；紫外灯和日光灯均会不同程度地加速5种单体成分的降解；与水溶液相比，金属离子环境下5种单体成分半衰期明显缩短，且对其降解速率的影响程度为Fe³⁺＞Fe²⁺＞Na⁺。[结论] 女贞子中5种环烯醚萜苷类成分不稳定，其稳定性受酸碱、高温、光照以及金属离子的影响，在运输或存放时应避免长时间照射、保持低温、pH近中性，且应避免与金属离子尤其是Fe³⁺接触。

Abstract:

[Objective] To study the degradation kinetic characteristics of five iridoid glycosides in Ligustrum luciduml in aqueous solution under different temperature,acid and base,light intensity and metal ion. [Methods] Ultra-high liquid chromatography(UPLC) was used to investigate the changes of the contents of five components with time in different environments. The degradation equation and a series of reaction kinetic parameters were obtained by chemical reaction kinetics method and the degradation law was summarized. [Results] The degradation rates of the five components were consistent with the first-order kinetic model under various conditions,and the degradation rate increases with increasing temperature. In addition,the other four components except nuezhenidic acid were stable under neutral condition,and the acid and alkalinity could be degraded to different degrees. Both UV lamp and fluorescent lamp could accelerate the degradation of the five monomer components in different degrees. Compared with aqueous solution,the half-life of the five monomer components was obviously shortened in metal ion environment,and the degree of degradation rate was Fe³⁺>Fe²⁺>Na⁺. [Conclusion] The five iridoid glycosides in Ligustrum lucidum are unstable,and their stability is affected by acid and alkali,high temperature,and illumination. During transportation or storage,it is necessary to avoid long-term light exposure,keep low temperature,pH near neutral,and avoid contact with metal ions,especially Fe³⁺。