人参皂苷Rd的理化性质及降解研究

采用RP-HPLC法和摇瓶法测定了人参皂苷Rd在水和不同pH介质中的平衡溶解度及其在正辛醇-水及各pH介质组成的体系中的表观油水分配系数(P_(app)),并考察了人参皂苷Rd在4个强降解条件下的降解情况。结果表明:在25℃时,人参皂苷Rd在水(pH 7.0)和不同pH(1.0,2.0,4.0,5.8,6.8,7.4)介质中的平衡溶解度依次为0.224,0.015,0.050,0.116,0.136,0.439,0.201 g/L;人参皂苷Rd在水中的Papp=32.45(lg Papp=1.51),在不同pH介质中的油水分配系数均接近或大于1;人参皂苷Rd在0.1 mol/L Na OH、0.1 mol/L HCl、70℃、0.3%H2O24个强降解条件下,放置7 d后的降解率分别为20.02%、88.53%、28.15%、69.81%。上述研究结果表明:人参皂苷Rd极微溶于水,脂溶性好,且不同的pH对其溶解度和Papp均具有较大影响,在碱和高温条件下较稳定,在酸和氧化条件下降解较快。

Physicochemical Properties and Degradation Behaviors of Ginsenoside Rd

The equilibrium solubility and the apparent partition coefficient of ginsenoside Rd in series medium of different pH values were measured by RP-HPLC and shake-flask method.The destructive tests of ginsenoside Rd were also performed in four conditions.Results show that at 25℃,the equilibrium solubility of ginsenoside Rd in water and in different media (1.0,2.0,4.0,5.8,6.8,7.4)was 0.224,0.015,0.050,0.116,0.136,0.439 and 0.201 g/L,respectively.The Papp of ginsenoside Rd was 32.45 (lgPapp =1.51).The partition coefficients of ginsenoside Rd were close to or greater than 1 in different pH conditions.After 7 days,the degradation rates of ginsen oside Rd in four forced conditions were 20.02％,88.53％,28.15％ and 69.81％,respectively.The results of this study indicated that ginsenoside Rd showed poor water solubility and good lipid solubility,and the solubility and P app were affected by the various pH values.The degradation of gin senoside Rd under alkali and high temperature conditions was relatively slow,and ginsenoside Rd was unstable under acid or oxidizing conditions.