Xu Xu, Dong Xiao-wei, Mao Ping
State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, China.
Yao Xue Xue Bao. 2003 Oct;38(10):779-82.
To study the thermodynamics of precipitation reaction and kinetics between berberine and rheinic acid. The former is the main compound in rhubarb root or corktree bark, the latter is a representation of anthraquinone compounds that are the main kind compound in coptis rhizome. The precipitate produced in preparation of complex prescription of Chinese herbal medicines Xiexin decoction and Shaoyao decoction had made an appeal. The work should build a good basement for two decoctions research and development.
Capillary electrophoresis (CE) and front analysis methods are used for determining two compounds' equilibrium concentration at different precipitate conditions to calculate the constants of thermodynamics and kinetics.
The molar ratio of berberine and rheinic acid in precipitate is 1:1. The solubility product constant Ksp = [B] [R] = (3.29 +/- 0.19) x 10(-9) mol2.L-2. The precipitate reaction is an endotherm process and Ksp shows less effect by temperature. The reaction occurred immediately even though the precipitate cannot be observed in time. The precipitate process in experiments is practically just an aging or grown process of the precipitate particles. High temperature can quicken the aging.
The precipitate in Chinese herbal medicines Xiexin decoction and Shaoyao decoction should be resulted from anthraquinone compounds and alkaloids. The reproductivity of capillary electrophoresis can be improved for simple sample by combining peak height measurement.
研究小檗碱与大黄酸沉淀反应的热力学及动力学。小檗碱是大黄根茎或黄柏树皮中的主要成分，大黄酸是蒽醌类化合物的代表，而蒽醌类化合物是黄连根茎中的主要化合物类型。中药泻心汤和芍药汤复方制剂中产生的沉淀引发了关注。该研究应为这两种汤剂的研发奠定良好基础。
采用毛细管电泳（CE）和前沿分析法测定两种化合物在不同沉淀条件下的平衡浓度，以计算热力学和动力学常数。
沉淀中小檗碱与大黄酸的摩尔比为1:1。溶度积常数Ksp = [B][R] = (3.29 ± 0.19)×10⁻⁹ mol²·L⁻²。沉淀反应是吸热过程，Ksp受温度影响较小。即使不能及时观察到沉淀，反应也会立即发生。实验中的沉淀过程实际上只是沉淀颗粒的老化或生长过程。高温可加速老化。
中药泻心汤和芍药汤中的沉淀应是由蒽醌类化合物和生物碱所致。通过结合峰高测量，可提高毛细管电泳对简单样品的重现性。
