Different modes of DNA cleavage activity of dihydroxo-bridged dicopper(II) complexes having phenanthroline bases

Dihydroxo-bridged dicopper(II) complexes [{Cu(phen)} 2(μ-OH) 2](ClO 4) 2 ( 1), [{Cu(dpq)} 2(μ-OH) 2](ClO 4) 2 ( 2) and [{Cu(dppz)(DMF)} 2(μ-OH) 2](PF 6) 2 ( 3), where phen, dpq and dppz are 1,10-phenanthroline, dipyridoquinoxaline and dipyridophenazine, respectively, are prepared and their DNA bindi...

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Bibliographic Details
Published in:Journal of inorganic biochemistry 2004-06, Vol.98 (6), p.1087-1094
Main Authors: Thomas, Anitha M., Nethaji, Munirathinam, Chakravarty, Akhil R.
Format: Article
Language:English
Subjects:
Animals
Cattle
Copper - chemistry
Crystal structure
Dicopper(II) complexes
DNA - chemistry
DNA cleavage
Groove selectivity
Molecular Structure
Organometallic Compounds - chemical synthesis
Organometallic Compounds - chemistry
Oxidation-Reduction
Phenanthroline bases
Phenanthrolines - chemistry
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Summary:Dihydroxo-bridged dicopper(II) complexes [{Cu(phen)} 2(μ-OH) 2](ClO 4) 2 ( 1), [{Cu(dpq)} 2(μ-OH) 2](ClO 4) 2 ( 2) and [{Cu(dppz)(DMF)} 2(μ-OH) 2](PF 6) 2 ( 3), where phen, dpq and dppz are 1,10-phenanthroline, dipyridoquinoxaline and dipyridophenazine, respectively, are prepared and their DNA binding and cleavage properties studied. Complex 3 has been structurally characterized by X-ray crystallography. The complexes have a {Cu 2(μ-OH) 2} 2+ core with an essentially planar arrangement of two CuN 2O 2 basal planes. The complexes are avid binder to calf thymus DNA ( K app value of 4.8 × 10 6 and 5.9 × 10 6 M −1 for 2 and 3, respectively, from ethidium displacement assay) and exhibits significant cleavage of supercoiled (SC) pUC19 DNA in dark in presence of mercaptopropionic acid. Besides, the dpq and dppz complexes display photo-induced DNA cleavage on UV (312 nm) and red light (632.8 nm) irradiations in absence of any additives. Mechanistic investigations reveal minor groove binding for the phen and dpq complexes, and major groove preference for the dppz species. The oxidative DNA cleavage reactions in presence of mercaptopropionic acid as a reducing agent involve hydroxyl radicals. The photo-cleavage reactions at UV light involve singlet oxygen as the reactive species, while similar reactions on red light irradiation (632.8 nm) proceed through the formation of hydroxyl radical. The complexes show significant DNA hydrolase activity in absence of any additives under dark reaction conditions.
ISSN:0162-0134
1873-3344
DOI:10.1016/j.jinorgbio.2004.02.029