常见还原性物质还原五价无机砷的实验研究

目的研究还原型谷胱甘肽(GSH)、半胱氨酸(Cys)、维生素C(VC)和亚铁离子(Fe2+)等常见还原性物质对五价无机砷As(Ⅴ)]的还原作用及特点。方法模拟体内环境建立还原体系37℃、pH7.0的磷酸盐缓冲液、3μmol/L As(Ⅴ)、60mmol/L巯基化合物(GSH和Cys)、0~30mmol/L VC、0~40mmol/LFe2+],采用高效液相色谱-氢化物发生-原子荧光法(HPLC-HG-AFS)检测各种反应过程中的三价无机砷As(Ⅲ)]和As(Ⅴ)。结果As(Ⅴ)还原率和As(Ⅲ)生成率随GSH浓度增加(0~60mmol/L)而增加;当GSH浓度为60mmol/L时,As(Ⅴ)还原率和As(Ⅲ)生成率达到峰值;随着GSH浓度继续增加(60~80mmol/L),As(Ⅴ)还原率和As(Ⅲ)生成率反而下降;巯基化合物中的巯基(-SH)在还原As(Ⅴ)过程中起关键作用,60mmol/L的-SH反应30分钟后As(Ⅴ)还原率达到60%,As(Ⅴ)还原率与-SH的具体存在形式(GSH或Cys)无关;单独VC或Fe2+不能还原As(Ⅴ),但是当VC浓度大于10mmol/L或Fe2+浓度大于20mmol/L时,可以增加60mmol/L的-SH的还原作用(P<0.01)。结论巯基化合物中的-SH可以非酶促还原As(Ⅴ),VC和Fe2+可以增强-SH的还原作用。

Study of the arsenate reducted by common reducing agents

OBJECTIVE: To study the role of glutathione (GSH), cysteine (Cys), vitamin C (VC) and ferrous ion (Fe2+) in the reduction of arsenate As (V)] and the characteristic of reduction. METHODS: The reaction conditions (37 degrees C, pH7.0 phosphate buffer) and the concentrations of As (V) (3 micromol/L), GSH (60 mmol/L), Cys (60 mmol/L), VC (0-30 mmol/L) and Fe2+ (0-40 mmol/L)] were simulated in vitro. ArseniteAs(III)] and As(V)] were determined by the high performance liquid chromatography-hydride generation-atomic fluorescence spectrometry (HPLC-HG-AFS). RESULTS: The reduction, of As(V) and As(III) formation, increased with the concentration, of GSH (0-60 mmol/L), and reached a maximum values at the concentration of 60 mmol/L GSH, then decreased with the concentration of (60-80 mmol/L) GSH. -SH in sulfhydryl compound, could play an important role in the reduction of As(V), and at the concentration of 60 mmol/L -SH (both GSH and Cys) could reduce 60%, of As(V) to As(III) for 30 min. VC or Fe2+ could not reduce As(V) alone, but when the concentration of VC or Fe2+ reached to 10 mmol/L or 20 mmol/L, they could have a significantly synergistic effect with 60 mmol/L -SH on the reduction of As(V) (P < 0.01). CONCLUSION: SH could reduce As(V) alone without any reductase. VC and Fe2+ could have a synergistic effect with -SH on the reduction of As(V).