Binuclear copper and zinc complexes possessing bio-potential ligands: synthesis, characterization, antimicrobial, SOD mimetic, DNA binding, and cleavage studies

• Published in: Journal of coordination chemistry Vol. 63; no. 6; pp. 1080 - 1096
• Main Authors: Raman, N., Sakthivel, A., Jeyamurugan, R.
• Format: Journal Article
• Language: English
• Published: Abingdon Taylor & Francis Group 01-03-2010; Taylor & Francis Ltd
• Subjects: Absorption spectroscopy; Antimicrobial; Antimicrobial agents; Binding constant; Chloride; Copper; Data processing; Deoxyribonucleic acid; distamycin; DNA; Fungi; Nuclease; Oxygen; Photo-cleavage; Reducing agents; Schiff base; SOD; Sodium azide; Superoxide dismutase; U.V. radiation; Viscosity; Zinc
• ISSN: 0095-8972; 1029-0389
• DOI: 10.1080/00958971003699745

Schiff bases (L) viz, N,N′,N′′,N′′′-tetra-3,4-dimethoxybenzalidene-3,3′-diaminobenzidine (TDBD), N,N′,N′′,N′′′-tetra-4-hydroxy-3-methoxybenzalidene-3,3′-diaminobenzidine (THMBD), and N,N′,N′′,N′′′-tetra-3-hydroxy-4-nitrobenzalidene-3,3′-diaminobenzidine (THNBD) afford binuclear [M
2
LCl
4
] complexes where M = Cu(II) or Zn(II). These Schiff bases and their binuclear complexes have been characterized by analytical and spectral data showing square-planar geometry on metalation with Cu
2+
. Intercalative binding of these complexes with DNA has been investigated by electronic absorption spectroscopy, viscosity measurements, cyclic voltammetry, and differential pulse voltammetry. Control DNA cleavage experiments using pUC19 supercoiled (SC) DNA and minor groove binder distamycin suggest that these synthesized complexes bind to the major groove. In the presence of a reducing agent like 3-mercaptopropionic acid (MPA), they show chemical nuclease activity. They also show an efficient photo-induced DNA cleavage on irradiation with a monochromatic UV light of 360 nm in the presence of inhibitors. Control experiments indicate the inhibition of cleavage in the presence of singlet oxygen quencher like sodium azide and the enhancement of cleavage in D
2
O show the formation of singlet oxygen as reactive species. The superoxide dismutase (SOD)-mimetic activity of the synthesized complexes has been assessed for their ability to inhibit the reduction of nitroblue tetrazolium chloride (NBT). The complexes have promising SOD-mimetic activity. The antimicrobial results indicate that the complexes inhibit the growth of bacteria and fungi more than free ligands.