人参皂苷R_d及其C_(12)手性异构体对缺氧/再复氧后蛋白酪氨酸磷酸化的抑制作用

目的　探讨人参皂苷Rd C12 手性碳构型改变与其药理活性的关系。方法　建立牛主动脉内皮细胞 (BAEC)缺氧 /再复氧 (H/R)损伤模型 ;MTT法研究Rd 及Rd C12 手性异构体 (12 epi Rd)对H/R损伤BAEC的保护作用 ;Western印迹法检测蛋白酪氨酸磷酸化 (TPP)水平 ,研究二者对H/R损伤BAEC的TPP水平的影响。结果　 0 .5～ 6 4μmol·L- 1的Rd 及12 epi Rd 能浓度依赖性的保护H/R损伤的BAEC ,二者所能达到的最大存活率分别为 (72 .7± 1.5 ) %和 (70 .0± 1.5 ) % ,EC50 分别为 (1.0 6± 0 .19)和 (1.88±0 .5 5 ) μmol·L- 1(P <0 .0 5 )。Rd 及 12 epi Rd 均可抑制H/R引起的TPP水平的提高 ,浓度为 1,4 ,16μmol·L- 1时 ,Rd 的抑制率分别可达 (2 4 .3± 6 .8) % ,(5 2 .6± 8.7) %及 (73.4± 11.4 ) % ;而 12 epi Rd 的抑制率分别可达 (12 .8± 4 .4 ) % ,(2 4 .1± 10 .3) %及(4 2 .5± 13.0 ) % ,二者在三个浓度点的抑制率均有显著性差异 (P <0 .0 5 )。结论　人参皂苷Rd C12 手性碳构型的改变对其保护H/R损伤BAEC的作用及抑制H/R诱导的TPP水平增强的作用有一定的影响。RdC12 手性碳构型改变明显降低其抑制TPP增强的作用可能是其保护作用下降的重要原因之一。

Inhibitory effects of ginsenoside-Rd and its C12 isomer on tyrosine-phosphorylation induced by hypoxia/reoxygenated injury

AIM To investigate the relationship between the construction of chiral C₁₂ of ginsenoside and its pharmacological effects. METHODS A hypoxia-reoxygenated (H/R) model of cultured bovine aortic endothelial cells(BAEC) in vitro was established. The protective effects of ginsenosides R_d and 12-epi-R_d on H/R BAEC were studied by MTT. The effects of Rd and 12-epi-R_d on tyrosine phosphorylated protein (TPP) improved by H/R in BAEC were studied by Western blot. RESULTS Both R_d and 12-epi-R_d(0.5－64 μmol&#8226;L^-1) remarkably increased the survival rates of H/R BAEC (50.6±2.8)% in a concentration-dependent manner. The maximal survival rate of Rd (72.7±1.5)% was higher than that of 12-epi-R_d (70.0%±1.5)% (P<0.05); the EC₅₀(1.06±0.19)μmol&#8226;L^-1 of R_d to protect H/R BAEC was lower than the EC₅₀ (1.88±0.55)μmol&#8226;L^-1 of 12-epi-R_d (P<0.05). Both R_d and 12-epi-R_d had inhibitory effects on TPP in H/R BAEC after 2 h of reoxygenation. When the concentration of R_d and 12-epi-R_d were 1, 4, 16 μmol&#8226;L^-1, respectively, the inhibitory rates of Rd were (24.3±6.8)%, (52.6±8.7)% and (73.4±11.4)%, while the inhibitory rates of 12-epi-R_d were (12.8±4.4)%, (24.1±10.3)% and (42.5±13.0)%, respectively. Their inhibitory rates all had significant differences on each concentration (P<0.05). CONCLUSION The changing of the construction of chiral C₁₂ of R_d did alter its protective effects on H/R BAEC and its inhibitory effects on TPP in H/R BAEC. The reduced inhibitory effects induced by the changing of the construction of chiral C₁₂ may be one of the most important reasons for its reduced protective effects on H/R BAEC.