Synthesis, DNA binding, nuclease activity and cytotoxic studies of a wheel-shaped octanuclear copper(II) complex based on 1,2,4-triazole

The antitumor activity shown by many platinum complexes has produced a strong interest in research of new organometallic compounds. Among the metal compounds synthesized and tested, copper compounds have received considerable attention because of their cytotoxic activity against solid tumors. A novel wheel-shaped octanuclear copper(II) complex with a 1,2,4-triazole derivative ligand formulated as [Cu8L4](ClO4)(8)11H(2)O (1) (L=3,5-bis((bis(2-hydroxylethyl)amino)methyl)-4H-1,2,4,-triazole-4-amine) has been synthesized and structurally characterized. In 1, eight Cu atoms are linked through 1,2,4-triazole units and alkoxide bridges to form a centrosymmetric octanuclear Cu(II) metallomacrocycle. The interaction of complex 1 with calf thymus DNA has been studied using UV absorption, fluorescence and circular dichroism spectroscopies, viscosity measurements and cyclic voltammetry. The apparent binding constant (k(app)) value for 1 is 1.59x10(5)M(-1). Furthermore, complex 1 displays efficient oxidative cleavage of supercoiled DNA in the presence of external agents, the rate constant for the conversion of supercoiled to nicked DNA being 2.67x10(-5)s(-1). Interestingly, cytotoxicity studies on the MCF-7 human breast cancer cell line show that the IC50 value of 1 is less than that of cisplatin for the same cell line, revealing that it has the potential to act as an effective metal-based anticancer drug. Copyright (c) 2016 John Wiley & Sons, Ltd.