Anomalous behavior of pentacoordinate copper complexes of dimethylphenanthroline and derivatives of terpyridine ligands: Studies on DNA binding, cleavage and apoptotic activity

Copper(II) complexes with substituted terpyridine ligands, namely [Cu(itpy)(dmp)](NO3)2 (1) and [Cu(ptpy)(dmp)](NO3)2 (2) have been synthesized and characterized. The interaction of the complexes with CT-DNA has been explored using spectroscopic techniques and viscosity. Complexes 1 and 2 bind in the grooves of DNA, interestingly 1 in the minor and 2 in the major groove. Both the complexes have been found to promote DNA cleavage; complex 1 through hydrolytic and 2 oxidative. Complexes 1 and 2 have been found to be cytotoxic and bring about apoptosis of human lung cancer cell line A549.

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► Synthesis of two pentacoordinate Copper(II) complexes and characterization by X-Ray crystal diffraction.
► Both the complexes are avid DNA binders.
► Complex 1 binds in the minor groove whereas complex 2 binds in the major groove of DNA.
► Complex 1 cleaves DNA hydrolytically whereas complex 2 cleaves in the presence of hydrogen peroxide.
► Both the complexes bring about apoptosis of A549 lung cancer cell line.