Synthesis, characterization, DNA-binding and biological studies of novel titanium (IV) complexes

Abstract

A series of novel binuclear titanium (IV) complexes, [Ti(sal)LI–V(OBu)(μ-OBu)]2, was synthesized by the reaction of salicylic acid (H2sal) and substituted indoles (LI = Tryptophol, LII = 5-Methoxyindole, LIII = Indole-5-Carboxaldehyde, LIV = 5-Cyanoindole, LV = 6-Nitroindole) with titanium(IV) tetrabutoxide in predetermined molar ratios under stirring and refluxing conditions in THF solvent. The chemical structure of synthesized complexes was found to be binuclear based on the FTIR, IH (proton) NMR and ESI-Mass (Electron-spray ionization) spectroscopic data. Each titanium metal was surrounded by two bridged butoxy groups and one terminal butoxy group along with bidentate salicylic acid and coordinated substituted indoles. These complexes were investigated for antioxidant potential using DPPH (2,2-diphenyl-1-picrylhydrazyl) assay where they exhibited moderate to good antioxidant activity. Gel electrophoresis method was employed to study the ct-DNA (calf thymus DNA) cleavage efficiency of complexes using an agarose gel. Antimicrobial results stated that most of the complexes were ineffective against selected bacterial and fungal strains. Complexes were investigated for anticancer activity against two selected cancerous cell lines (L6 and L929). From MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay, it has been inferred that complexes 1 and 2 have better anticancer properties than their respective indoles. The DNA binding study of synthesized complexes studied in order to check their efficacy to hinder DNA replication/transcription using electronic absorption and fluorescence spectroscopy revealed them as electrostatic/groove binder. The synthesized complexes were also evaluated for antidiabetic properties using alpha-amylase inhibition assay and complex 5 possessed better alpha-amylase inhibition activity than other complexes. Synopsis: The synthesis, structural characterizationand biological activities of a novel binuclear titanium(IV) complexes [Ti(sal)LI–V(OBu)(μ-OBu)]2 is reported.