Single crystal, DNA interaction and cytotoxicity studies of rhenium(I) organometallic compounds

Abstract

A series of seven rhenium(I) complexes [(Re(CO)3L1−7)Cl], where L = 2-(1-phenyl-5-(p-tolyl)-4,5-dihydro-1H-pyrazol-3-yl)pyridine (L1), 2-[5-(4-bromophenyl)-1-phenyl-4,5-dihydro-1H-pyrazol-3-yl]pyridine (L2), 1-(6-bromopyridin-2-yl)ethan-1-one (L3), 1-(6-methoxypyridin-2-yl)ethan-1-one (L4), 4-phenyl-2-(pyridin-2-yl)quinoline (L5), 6-chloro-4-phenyl-2-(pyridine-2-yl)quinolone (L6), 6-chloro-4-(2-chlorophenyl)-2-(pyridine-2-yl)quinolone (L7) were synthesized and characterized by spectroscopic techniques. The geometry of complex (V) was confirmed by single crystal analysis, which suggests distorted octahedral geometry of all complexes and complemented by UV–Visible spectra of complexes. Absorption titration and viscosity measurement studies of HS DNA under the influence of complexes were carried out to evaluate the binding capabilities and binding mode. The data of above studies suggest groove mode of binding (Kb = 0.9–21.3 × 105 M−1), which is also supported by molecular docking study and groove binding competition assay. The cytotoxicity of complexes was screened against S. pombe cells at the cellular level and against HCT116 cancer cell line. The IC50 values show the potent cytotoxic nature of complexes (I), (II), (V) and (VII) against HCT116 cancer cell line. The ability of complexes to cleave genomic DNA (DNA smearing) of S. pombe cells was studied by gel electrophoresis. The antibacterial activity of coordination compounds was evaluated against 2 g-positive and 3 g-negative pathogens, which suggests that complexes (MIC = 68–104 μM) have better antibacterial activity than all ligands (MIC = 272–320 μM). The toxicity of complexes was checked on brine shrimp in terms of their LC50 values (13.0–18.5 μM).