US EPA

614198 

Journal Article 

DNA binding and oxidative DNA cleavage activity of (μ-oxo)diiron(iii) complexes in visible lightElectronic supplementary information (ESI) available: Figures for spectral, magnetic, redox, DNA binding and cleavage data (Fig. S1-S11). See 

Mithun, R; Ramkumar, S; Akhil, RC 

2009 

Yes 

Dalton Transactions
ISSN: 1477-9226
EISSN: 1477-9234 

2009 

6 

1024-1033 

Four (μ-oxo)diiron(iii) complexes [Fe2(μ-O)(H2O)2B4](ClO4)4(1and 2) and [Fe2(μ-O)(μ-O2CMe)B4](ClO4)3(3and 4), where B = 1,10-phenanthroline (phen) and dipyrido[3,2-d:2′,3′-f]quinoxaline (dpq), are prepared and their DNA binding and cleavage activity studied. The complexes show DNA binding propensity giving Kbvalues of 3.6–9.3 × 104M−1. The viscosity and DNA melting data suggest a surface and/or groove binding nature of the complexes to calf thymus (CT) DNA. The DNA binding data obtained from isothermal calorimetric study indicate two binding modes involving surface aggregation and/or partial intercalation of the phenanthroline bases to CT DNA. All the complexes show chemical nuclease activity in the presence of 3-mercaptopropionic acid as a reducing agent following a mechanistic pathway that involves formation of superoxide and hydroxyl radicals. Photoirradiation of pUC19 DNA at 365 nm in the presence of 1–4show that the complexes, barring 1, are efficient photocleavers of supercoiled DNA to its nicked circular form. Complexes 2–4display photocleavage activity in visible light of different wavelengths. Complexes 3and 4exhibit significant DNA cleavage activity in red light of 633 nm, the wavelength known for the activity of the photodynamic therapeutic drug Photofrin®. The mechanistic study using various additives suggests a minor groove binding nature of the complexes with the formation of singlet oxygen from the quinoxaline moiety of dpq and hydroxyl radical from photodecarboxylation of the acetate ligand as the reactive oxygen species. [ABSTRACT FROM AUTHOR] Copyright of Dalton Transactions: An International Journal of Inorganic Chemistry is the property of Royal Society of Chemistry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts) 

DNA-ligand interactions; IRON compounds; METAL complexes; OXIDATION-reduction reaction; THYMUS; QUINOXALINES; ACTIVE oxygen; DECARBOXYLATION