三七总皂苷对小鼠肝脏谷胱甘肽-S-转移酶的抑制作用及其动力学分析

Inhibition of glutathione-S-transferase by total saponins of Panax notoginseng and its kinetics analysis in liver of mice

目的:研究三七总皂苷(total saponins of Panax notoginseng,PNS)对小鼠肝脏谷胱甘肽-S-转移酶(glutathione-S-transferase,GST)的抑制作用及其酶动力学。方法:采用差速离心法制备小鼠胞质液酶,用半数效量概率单位法及Lineweaver-Burk双倒数作图法求得小鼠肝脏GST的米氏常数(Km)、最大反应速度(Vmax)和三七总皂苷对小鼠肝脏GST的半数抑制浓度(IC50)以及判断三七总皂苷对GST的抑制类型和抑制常数(KI,KIS)。结果:三七总皂苷对小鼠肝脏GST有抑制作用,其IC50是189.54 mg.L-1;对底物还原型谷胱甘肽(GSH),GST的Km是0.456 3 mmol.L-1,Vmax是476.19 U.mg-1;对底物1-氯-2,4-二硝基苯(CDNB),GST的Km是0.109 7 mmol.L-1,Vmax是400.00 U.mg-1。对底物GSH,三七总皂苷对小鼠肝脏GST属于混合性抑制,其抑制常数KI是0.27 mg.L-1,KIS是0.68 mg.L-1;对底物CDNB,三七总皂苷对小鼠肝脏GST属于混合性抑制,其抑制常数KI是0.21 mg.L-1,KIS是0.66 mg.L-1。结论:三七总皂苷对小鼠肝脏GST的活性有明显抑制作用。

Objective： To study the inhibition of glutathione-s-transferase by total saponins of Panax notoginseng and its kinetics analysis in liver of mice. Method： Mouse liver cytochyma enzyme was obtained by different velocity centrifugation, the mouse liver glutathione-S-transferase of michaelis constant （Km ）, maximum velocity （ Vmax ） and the inhibition of glutathione-S-transferase by total saponins of P. notoginseng of 50% inhibiting concentration （ IC50 ）, inhibition constant （ KI, KIS）, the type of inhibition were calculation by Lineweaver-Burk and the low of semi-effect-probit. Result： It was found that total saponins of P. notoginseng inhibited the glutathione-S-transferase activity with IC50 of 189. 54 mg · L-1 . Kinetics analysis showed the glutathione-S-transferase of Km was O. 456 3 mmol. L-1 and Vmax was 476. 19 U · mg-1 with reduced glutathione （GSH） substrate, O. 109 7 mmol · L-1 （Kin） and 400. 00 U · mg -1 （ Vmax ） with 1-chloro-2,4-dinitrobenzene （ CDNB ） substrate. Kinetics studies of total saponins of P. notoginseng on glutathione-S-transferase showed the inhibition were belong to mix-type with GSH and CDNB ; the inhibition constant was 0. 27 mg · L-1 （ KI）, 0. 68 mg · L-1 （KIS） with GSH, and 0. 21 mg · L-1 （ KI）, 0. 66 mg · L-1 （KIS） with CDNB. Conclusion： Total saponins of P. notoginseng strongly inhibited the glutathione-S-transferase activity.