青蒿素及其衍生物电化学性质的研究Ⅱ: 青蒿素在 氯化血红素存在下的还原

用电化学方法研究了青蒿素与氯化血红素之间的相互作用。青蒿素在玻璃碳电极上于-1.08V处发生一个2电子转移的不可逆还原。但是,即使在低至4.0×10^-^8mol/L氯化血红素存在下,青蒿素仍可被催化还原,阴极过电位降低了600mV。配合物EDTA-Fe(Ⅲ)具有类似氯化血红素的催化性质,它降低了QHS阴极过电位590mV。在这个体系中,青蒿素在碳电极上的还原是一个借助于氯化血红素催化的还原过程,氯化血红素的存在降低了青蒿素还原活化能,促进了青蒿素的分解。文中讨论了该反应的还原机理。

Study on the Electrochemical Behaviors of Artemisinin(Qinghaosu) and Its Derivatives II. Reduction Mechanism of Artemisinin in the Presence of Hemin

The interaction between artemisinin and hemin was investigated by electrochemical methods. Artemisinin was irreversibly reduced at -1. 08V via a two-electron transfer process at glassy carbon electrode. In the presence of hemin at concentration as low as 4.0×10^-^8mol/L, artemisinin can be reduced via the hemin-catalysis and its original cathodic peak at -1.08V completely disappeared. The cathodic overpotential of artemisinin is decreased by ca. 600mV. This process is verified by the fact that complex EDTA-Fe(Ⅲ) can also promote the artemisinin reduction with decreasing the cathodic overpotential of artemisinin for 590mV. These results show that the reduction of artemisinin at glassy carbon electrode is a catalytic process with the aid of hemin. Hemin can greatly decrease the cathodic activation energy of the reduction of artemisinin and promote the decomposition of artemisinin.