New transition metal ion complexes with benzimidazole-5-carboxylic acid hydrazides with antitumor activity

Metal complexes of 2-methyl-1H-benzimidazole-5-carboxylic acid hydrazide (4a; L1) and its Schiff base 2-methyl-N-(propan-2-ylidene)-1H-benzimidazole-5-carbohydrazide (5a; L2) with transition metal ions e.g., copper, silver, nickel, iron and manganese were prepared. The complexes formed were 1:1 or 1:2 M:L complexes and have the structural formulae [Cu(L1)Cl(H2O)]Cl·3H2O (6), [Ag(L1)NO3(H2O)] (7), [Ni(L1)Cl2(H2O)2]·H2O (8), [Fe(L1)Cl3(H2O)]·3H2O (9) and [Mn(L1)2Cl(H2O)]Cl·3H2O (10) for ligand L1, and [Cu(L2)Cl2(H2O)2]·H2O (11), [Ag(L2)2]NO3·H2O (12), [Ni(L2)2Cl2]·5H2O (13), [Fe(L2)2Cl2]Cl·2H2O (14) and [Mn(L2)Cl2(H2O)2]·H2O (15) for ligand L2. The antitumor activity of the synthesized compounds has been studied. The silver complex 7 was found to display cytotoxicity (IC50 = 2 μM) against both human lung cancer cell line A549 and human breast cancer cell line MCF-7.

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