Structural investigation, DNA interactions and in vitro anticancer studies of transition metal complexes of 3-(2-(2, 4-dihydroxy benzylidene) hydrazinyl) quinoxalin-2(1H) -one.

The Schiff base ligand, 3-(2-(2, 4-dihydroxybenzylidene) hydrazinyl) quinoxalin-2(1H)-one (RHQO) has been synthesized and characterized by spectral and single crystal X-ray analysis. The Mn(II), Ni(II) and Cu(II) complexes of RHQO have been synthesized and characterized by FT-IR, UV-VIS, mass, EPR spectra, CHN, thermo gravimetric analysis, magnetic susceptibility and conductivity measurements. The morphology of the ligand and complexes is studied by Scanning Electron Microscopy. The metal complexes formed were found to be polymeric in nature. The abilities of the ligand and its metal complexes to interact and bind with calf thymus DNA (CT-DNA) has been studied by electronic absorption spectroscopy and their quantitative binding strength was evaluated in terms of their intrinsic binding constant (Kb). The cleavage interaction of the ligand and its metal complexes with super coiled pBR 322 DNA has been investigated by agarose gel electrophoresis. Cytotoxicity of the Cu(II) and Ni(II) complexes was evaluated using various cancer cell lines, Human cervical cancer cell line (Hela), B16 melanoma F10(B16-F10), Human ovarian cancer cell (SKOV3) and Breast cancer cell line (MCF7) by MTT assay. The results indicated that the ligand and its metal complexes bind with CT-DNA by groove binding mode and cleaved the supercoiled pBR 322 DNA in to nicked form. The Ni(II) and Cu(II) complexes exhibited anticancer activity without affecting the normal CHO-K1 cell lines. Communicated by Vsevolod Makeev.