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Photocytotoxic Oxovanadium(IV) Complexes Showing Light-Induced DNA and Protein Cleavage Activity

Sasmal, Pijus K and Saha, Sounik and Majumdar, Ritankar and Dighe, Rajan R and Chakravarty, Akhil R (2010) Photocytotoxic Oxovanadium(IV) Complexes Showing Light-Induced DNA and Protein Cleavage Activity. In: Inorganic chemistry, 49 (3). pp. 849-859.

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Official URL: http://pubs.acs.org/doi/abs/10.1021/ic900701s


Oxovanadium(IV) complexes [VO(L)(B)]Cl-2 (1-3), where L is bis(2-benzimidazolylmethyl)amine and B is 1,10-phenanthroline(phen),dipyrido[3,2-d:2',3'-f]quinoxaline(dpq) or dipyrido[3,2-a:2',3'-c]phenazine (dppz), have been prepared, characterized, and their photo-induced DNA and protein cleavage activity studied. The photocytotoxicity of complex 3 has been studied using adenocarcinoma A549 cells, The phen complex 1, structurally characterized by single-crystal X-ray crystallography, shows the presence of a vanadyl group in six-coordinate VON5 coordination geometry. The ligands L and phen display tridentate and bidentate N-donor chelating binding modes, respectively. The complexes exhibit a d-d band near 740 nm in 15% DMF-Tris-HCl buffer (pH 7.2). The phen and dpq complexes display an irreversible cathodic cyclic voltammetric response near -0.8 V in 20% DMF-Tris-HCl buffer having 0.1 M KCl as supporting electrolyte. The dppz complex 3 exhibits a quasi-reversible voltammogram near -0.6 V (vs SCE) that is assignable to the V(IV)-V(III)couple. The complexes bind to calf thymus DNA giving binding constant values in the range of 6.6 x 10(4)-2.9 x 10(5) M-1. The binding site size, thermal melting and viscosity binding data suggest DNA surface and/or groove binding nature of the complexes. The complexes show poor ``chemical nuclease'' activity in dark in the presence of 3-mercaptopropionic acid or hydrogen peroxide. The dpq and dppz complexes are efficient photocleavers of plasmid DNA in UV-A light of 365 nm via a mechanistic pathway that involves formation of both singlet oxygen and hydroxyl radicals. The complexes show significant photocleavage of DNA in near-IR light (>750 nm) via hydroxyl radical pathway. Among the three complexes, the dppz complex 3 shows significant BSA and lysozyme protein cleavage activity in UV-A light of 365 nm via hydroxyl radical pathway. The dppz complex 3 also exhibits photocytotoxicity in non-small cell lung carcinoma/human lung adenocarcinoma A549 cells giving IC50 value of 17 mu M in visible light(IC50 = 175 mu M in dark).

Item Type: Journal Article
Publication: Inorganic chemistry
Publisher: American Chemical Society
Additional Information: Copyright for this article belongs to American Chemical Society.
Department/Centre: Division of Biological Sciences > Molecular Reproduction, Development & Genetics
Division of Chemical Sciences > Inorganic & Physical Chemistry
Date Deposited: 09 Feb 2010 11:28
Last Modified: 19 Sep 2010 05:54
URI: http://eprints.iisc.ac.in/id/eprint/25521

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