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Metal-assisted red light-induced DNA cleavage by ternary L-methionine copper(II) complexes of planar heterocyclic bases

Patra, Ashis K and Dhar, Shanta and Nethaji, Munirathinam and Chakravarty, Akhil R (2005) Metal-assisted red light-induced DNA cleavage by ternary L-methionine copper(II) complexes of planar heterocyclic bases. In: Dalton Transactions (5). pp. 896-902.

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Abstract

Ternary copper(II) complexes [Cu(L-met)B(Solv)](ClO4) (1-4), where B isa N,N-donor heterocyclic base like 2,2 bipyridine (bpy, 1),1,10-phenanthroline (phen, 2), dipyrido[3,2-d:2',3'-f]quinoxaline (dpq,3) and dipyrido[3,2-a:2',3'-c] phenazene (dppz, 4), are prepared and their DNA binding and photo-induced DNA cleavage activity studied(L-Hmet = L-methionine). Complex 2, structurally characterized by X-ray crystallography, shows a square pyramidal (4 + 1) coordination geometry in which the N,O-donor L-methionine and N, N-donor heterocyclic base bind at the basal plane and a solvent molecule is coordinated at the axial site. The complexes display a d-d band at similar to600 nm in DMF and exhibit a cyclic voltam metric response due to the Cu(II)/Cu(I)couple near -0.1 V in DMF-Tris-HCl buffer. The complexes display significant binding propensity to the calf thymus DNA in the order: 4(dppz) > 3 (dpq) >2 (phen) >> 1 (bpy).Control cleavage experiments using pUC19 supercoiled DNA and distamycin suggest major groove binding for the dppz and minor groove binding for the other complexes. Complexes 2-4 show efficient DNA cleavage activity on UV (365 nm) or red light (632.8 nm) irradiation via a mechanistic pathway involving formation of singlet oxygen as the reactive species. The DNA cleavage activity of the dpq complex 3 is found to be significantly more than its dppz and phen analogues.

Item Type: Journal Article
Additional Information: Copyright for this article belongs to Royal Society of Chemistry.
Department/Centre: Division of Chemical Sciences > Inorganic & Physical Chemistry
Date Deposited: 21 Mar 2005
Last Modified: 19 Sep 2010 04:18
URI: http://eprints.iisc.ernet.in/id/eprint/2958

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