Electrochemical activity of holotransferrin and its electrocatalysis-mediated process of artemisinin

Holotransferrin, the iron (III) transport protein in the blood, can significantly increase the anticancer activity of artemisinin, which is isolated from the Chinese plant qinghaosu. This paper investigates the action process of holotransferrin-induced electrocatalytic reduction of artemisinin by spectroscopic and electrochemical techniques. Results show that holotransferrin(Fe(III)) is the electrochemical sites of holotransferrin, which can catalyze the reduction of artemisinin through lowering the overpotential by about 80 mV. Compared with the different electrochemical behaviors of artemisinin with apotransferrin and holoprotein (apotransferrin in the presence of Fe(III)), respectively, it demonstrates that holotransferrin(Fe(III)) plays an important role in the electrocatalytic reduction of artemisinin, which can catalyze the cleavage of the endoperoxide bridge in artemisinin. A reliable two-step process is proposed to explain that artemisinin is activated by holotransferrin(Fe(III))-mediated electrocatalytic reduction. These results can provide further information for better understanding the anticancer action of holotransferrin-conjugated artemisinin.

A sequential two-step process is proposed to explain hololtransferrin-mediated electrocatalytic reduction of artemisinin. Holotransferrin (holo-TF) initially interacts with artemisinin (QHS) to form an adduct [holo-TF(Fe(ΙΙΙ))·QHS–(O–O)–]ads, subsequently, holo-TF(Fe(ΙΙΙ)) obtains one electron and then forms an intermediate adduct [holo-TF(Fe(ΙΙ))·QHS–(O–O)–]∗, which induces the cleavage of the peroxide bond in artemisinin and then generates QHS-(O)2 free radicals.Figure optionsDownload as PowerPoint slide