Design and synthesis of two new thiosemicarbazide based Schiff base metal complexes of nickel (II): DNA binding study and cytotoxicity profile analysis

Two new nickel (II) substituted thiosemicarbazone Schiff base complexes [Ni(meph)2] (1) [where H(2)meph = (2E)-N-methyl-2-[1-(pyridin-2-yl)ethylidene]hydrazine-1-carbothioamide] and [Ni(hmm)(2)](NO3)(2)& sdot;2H(2)O (2) [where H2hmm = (2E)-2-[(2-hydroxyphenyl)methylidene]-N-methylhydrazine-1-carbothioamide] have been designed and synthesized by the condensation of 4-methyl-3-thiosemicarbazide with 2-acetylpyridine and salicylaldehyde respectively. Both the metal complexes 1 and 2 are characterized using different available spectroscopic techniques like FT-IR, UV-Vis spectroscopy, elemental analysis, and single crystal X-ray structure analysis. X-ray crystal structure analysis reveal that complex 1 and 2 are octahedral Ni(II) complexes. The calfthymus CT-DNA-binding property of 1 and 2 has been evaluated by employing UV-Vis and fluorescence spectral titration. All the results show that CT-DNA binds with both nickel(II) complexes 1 and 2. In vitro cytotoxicity activity of complexes 1 and 2 toward A375 and MDA-MB-231 was evaluated using MTT assay and other methods which confirm that both complexes 1 and 2 behave as promising anti-cancer agents.