DNA BINDING AND CYTOTOXICITY STUDIES OF TERNARY COPPER(II) COMPLEXES CONTAINING HETEROCYCLIC BASES AND THIOUREA

This article describes the Cu(II) complexes including [Cu(phen)(L-val)TU)] 1 & [Cu(bpy)(L-val)TU)] 2 (phen = 1, 10-phenanthroline; bpy = 2,2’-bipyridyl, L-val = L-valine and TU = Thiourea). The complexes were synthesized by ligand substitution method and characterized by various physicochemical techniques. The intense UV band around 270 nm was due to n-π* transition. The binding behaviors of these complexes to cal thymus DNA (CT-DNA) were explored by spectroscopic titrations, emissions, viscosity measurements, and cyclic voltammetry. The binding constant value of complexes 1 and 2 was 8.42 × 10⁵ M^-1 and 7.12 × 10⁵ M^-1 respectively. Results suggest that the complex 1 can bind to CT-DNA through intercalation and complex 2 binds through partial intercalation. However, their binding ability differed, this may be attributed to the difference in ligand coordinated the metal centre, complex 1 shows higher binding affinity than complex 2, this is due to the extended π-conjugated system of phenanthroline ring. The cytotoxicity of complexes 1 and 2 evaluated by MTT assay; results indicated that complexes have significant cytotoxicity with HePG2 tumor cell line.