人参皂苷Rd的理化性质及降解研究

Physicochemical Properties and Degradation Behaviors of Ginsenoside Rd

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。

The equilibrium solubility and the apparent partition coefficient of ginsenoside Rd in series medium of different p H 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（ lgP_（app）= 1. 51）. The partition coefficients of ginsenoside Rd were close to or greater than 1 in different p H conditions. After 7 days,the degradation rates of ginsenoside 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 Pappwere affected by the various p H values. The degradation of ginsenoside Rd under alkali and high temperature conditions was relatively slow,and ginsenoside Rd was unstable under acid or oxidizing conditions.