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Photocytotoxicity and DNA cleavage activity of L-arg and L-lys Schiff base oxovanadium(IV) complexes having phenanthroline bases

Sasmal, Pijus K and Majumdar, Ritankar and Dighe, Rajan R and Chakravarty, Akhil R (2010) Photocytotoxicity and DNA cleavage activity of L-arg and L-lys Schiff base oxovanadium(IV) complexes having phenanthroline bases. In: Dalton Transactions (2003), 39 (30). pp. 7104-7113.

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Oxovanadium(IV) complexes [VO(sal-argH)(B)] Cl (1-3) and [VO(sal-lysH)(B)] Cl (4-6), where sal-argH2 and sal-lysH(2) are N-salicylidene-L-arginine and N-salicylidene-L-lysine Schiff bases and B is a phenanthroline base, viz. 1,10-phenanthroline (phen in 1 and 4); dipyrido[3,2-d: 2', 3'-f] quinoxaline (dpq in 2 and 5) and dipyrido[3,2-a: 2', 3'-c] phenazine (dppz in 3 and 6), have been prepared, characterized and their DNA photocleavage activity studied. Complex 1, characterized by X-ray crystallography, shows the presence of a vanadyl group in VIVO3N3 coordination geometry with a tridentate Schiff base having a pendant guanidinium moiety and bidentate phen ligand. The complexes exhibit a d-d band at similar to 715 nm in 20% DMF-Tris-HCl buffer. The complexes are redox active showing cathodic and anodic responses near -1.0 V and 0.85 V (vs. SCE) for the V(IV)-V(III) and V(V)-V(IV) couples, respectively, in DMF-Tris-HCl buffer. The complexes bind to calf thymus DNA giving Kb values in the range of 3.8 x 10(4) to 1.6 x 10(5) M-1. Thermal denaturation and viscosity data suggest DNA groove binding nature of the complexes. The complexes do not show any `chemical nuclease'' activity in dark in the presence of 3-mercaptopropionic acid or H2O2. The dpq and dppz complexes are efficient photocleavers of plasmid DNA in UV-A (365 nm) and red light (676 nm) via singlet oxygen pathway. The dppz complexes exhibit photocytotoxicity in HeLa cancer cells giving IC50 values of 15.4 mu M for 3 and 17.5 mu M for 6 in visible light while being non-toxic in dark giving IC50 values of > 100 mu M.

Item Type: Journal Article
Publication: Dalton Transactions (2003)
Publisher: Royal Society of Chemistry
Additional Information: Copyright of this article belongs to Royal Society of Chemistry.
Department/Centre: Division of Biological Sciences > Molecular Reproduction, Development & Genetics
Division of Chemical Sciences > Inorganic & Physical Chemistry
Date Deposited: 23 Aug 2010 09:52
Last Modified: 19 Sep 2010 06:14
URI: http://eprints.iisc.ac.in/id/eprint/31333

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