Biotin-tagged cis-dichlorido-oxidovanadium(IV) complex for DNA crosslinking and photo-induced apoptotic cytotoxicity

Abstract Cis-dichlorido-oxidovanadium(IV) complexes [VO(dpa/L1)Cl2] (1, 2) of dipicolylamine (dpa, 1 as control species) and 5-[(3aS,4S,6aR)-2-oxohexahydro-1H-thieno[3,4-d]imidazol-4-yl]pentanoic acid (biotin)-appended dpa (L1, 2 as active species) were prepared and their anticancer activity studied. Single crystal X-ray diffraction analysis of complex 1 revealed a cis arrangement of two chloride ligands in a distorted octahedral geometry with VIVON3Cl2. The dpa ligand displayed a facial mode of coordination. The complexes were 1:1 electrolytic in an aqueous medium and showed a significant enhancement of conductivity on irradiation with visible light. Complex 2 having the biotin moiety showed cytotoxicity in visible light of 400-700 nm giving IC50 value of 15.0(±0.2) µM in HeLa cells and 5.0(±1.2) μM in HepG2 cells. The complex did not show any apparent generation of reactive oxygen species (ROS) in dichlorofluorescein diacetate (DCFDA) assay. The complex displayed apoptotic photo-induced cytotoxicity following DNA crosslinking pathway as ascertained from the comet assay.