Interaction of rhenium(I) complex carrying long alkyl chain with Calf Thymus DNA: Cytotoxic and cell imaging studies

Abstract

The interaction of three rhenium(I)-diimine complexes carrying long alkyl chain fac-[Re(CO)3(α-diimine){4-C11py}] CF3SO31a–1c (α-diimine=2,2′-bipyridine (1a), 4,4′-di-tert-butyl-2,2′-bipyridine (1b), 4,4′-dinonyl-2,2′-bipyridine (1c); 4-C11py=(4-undecylpyridine) and fac-[Re(CO)3(α-diimine)(4-Etpy)]CF3SO3 (1d) (α-diimine=2,2′-bipyridine, 4-Etpy=4-Ethylpyridine) with Calf Thymus DNA (CT DNA) is studied by UV–vis absorption, luminescence and CD spectral techniques at pH 7.2. Spectral, viscosity and molecular docking studies unambiguously establish the formation of a groove binding between the Re(I) complex and CT DNA. The binding constant values of 1b and 1c are one order more than that of 1a and 1d indicating the importance of hydrophobic interaction of alkyl groups on bpy and py ligands with DNA. The complexes 1b and 1c exhibit the most pronounced antibacterial activity against four different microorganisms and all Re(I) complexes inhibit the growth of T and B cell lymphoma (Raji and Jurkat) cancer cells. Complex 1c exhibits the moderate cytotoxicity and cellular uptake of cancer cell lines attributed to the lipophilic alkyl chain on bpy and pyridine ligands which facilitate the hydrophobic interaction with DNA and healthy membrane permeability.