铜(Ⅱ)诱导双氢青蒿素过氧键断裂的电催化作用

Breakage of the Peroxy Bond in Dihydroartemisinin Induced by Electrocatalysis of Copper(Ⅱ)

双氢青蒿素(DHA)的过氧键是抗疟抗肿瘤作用的关键部位,过氧键的催化断裂将影响其药物活性.采用电化学方法研究了EDTA-Cu(Ⅱ)催化DHA过氧键的断裂,考察了酸度和扫描速率对体系的影响,并探讨了其催化作用的电极反应机理.结果表明,在含20%乙醇的B-R缓冲溶液(pH=7.2)中,一定浓度的EDTA-Cu(Ⅱ)使DHA于-0.681 V(vs SCE)处的还原峰峰电流上升,峰电位正移,表现出明显的电催化还原特征.当EDTA-Cu(Ⅱ)浓度为5.0×10-6mol/L,DHA浓度为5.0×10-4mol/L时,DHA的还原过电位降低了94 mV.与相同浓度的EDTA-Fe(Ⅲ)和血红素相比,EDTA-Cu(Ⅱ)具有更明显的催化效果,能催化DHA过氧键断键,从而影响DHA的药理活性.

The peroxy bond in dihydroartemisinin （DHA） is the most essential part for its anti-malarial and antitumor effect. The cleavage of the peroxy bond can affect its pharmacological activity. An electrochemical method was used to investigate the breakage of the peroxy bond in dihydroartemisinin induced by electrocatalysis of EDTA-Cu（Ⅱ）. The effect of acidity and scan rate on this catalytic system was studied. The mechanism of the re- action at the electrode surface was also discussed. There was an irreversible reduction peak at -0.681 V （vs SCE） for DHA in a B-R buffer solution containing 20 % ethanol （pH = 7.2）. The reduction potential shifted about 94 mV toward the positive direction, and the reduction current increased in the solution containing 5.0 × 10^-4 mol/L DHA and 5.0 × 10^-6 mol/L EDTA-Cu（ Ⅱ ）. Compared with EDTA-Fe（ Ⅲ ） and hemin, EDTA-Cu （ Ⅱ ） showed an obvious electrocatalytic effect to DHA in this system. These results indicated that EDTA-Cu （ Ⅱ） can induce the cleavage of the peroxy bond of DHA and affect the pharmacological activity of DHA.