Mitochondria‐Targeted Photoinduced Anticancer Activity of Oxidovanadium(IV) Complexes of Curcumin in Visible Light

Oxidovanadium(IV) complexes [VO(py‐aebmz)(B)]Cl ( 1 , 2 ) and [VO(napth‐py‐aebmz)(cur)]Cl [ 3 ; py‐aebmz = 2‐(1 H ‐benzimidazol‐2‐yl)‐ N ‐(pyridin‐2‐ylmethylene)ethanamine, HB = acetylacetone (Hacac, 1 ) and curcumin (Hcur, 2 ), napth‐py‐aebmz = naphthalimide conjugated to py‐aebmz ] have been prepared, characterized and their photoinduced DNA cleavage activities and photocytotoxicities studied. Complexes 1 – 3 each exhibited an irreversible cyclic voltammetric response of the V IV /V III redox couple at around –0.85 V versus SCE in dmf/0.1 M tbap. The complexes showed DNA photocleavage activity in visible light of 454, 530 and 647 nm through hydroxyl radical and singlet oxygen pathways. Fluorescence microscopy data suggest mitochondrial localization of complex 3 bearing a naphthalimide with a two‐fold increase in photocytotoxicity in HaCaT cells with an IC 50 value of 6.3 μ M and a three‐fold increase in MCF‐7 cells with an IC 50 of 5.4 μ M compared with complex 2 . Both 2 and 3 were non‐toxic in the dark.