Oxidative and hydrolytic DNA cleavage by Cu(II) complexes of salicylidene tyrosine schiff base and 1,10 phenanthroline/bipyridine

Ternary Cu(II) complexes [Cu(II)(saltyr)(B)] (1,2), (saltyr = salicylidene tyrosine, B = 1,10 phenanthroline (1) or 2,2′ bipyridine (2)) were synthesized and characterized by various techniques. The complexes exhibit square pyramidal (CuN3O2) geometry. CT-DNA binding studies revealed that the complexes show good binding propensity (Kb = 3.47 × 104 M−1 and 3.01 × 104 M−1 for 1 and 2, respectively). The role of these complexes in the oxidative and hydrolytic DNA cleavage was studied. The catalytic ability of 1 and 2 follows the order: 1 > 2. The rate constants for the hydrolysis of phosphodiester bond were determined as 2.80 h−1 and 2.11 h−1 for 1 and 2, respectively. It amounts to (0.58–0.77) × 108 fold rate enhancement compared to non-catalyzed DNA cleavage, which is significant.

Graphical abstractOxidative and hydrolytic cleavage of pUC19 DNA by Cu(II)–salicylidene tyrosine schiff base-1,10 phenanthroline complex at physiological conditions.Figure optionsDownload full-size imageDownload as PowerPoint slideResearch highlights► Tyrosine schiff base Cu(II) complexes [Cu(II)(saltyr)(B)] (1,2), (B = 1,10 phenanthroline (1) or 2,2′ bipyridine (2)) were synthesized and characterized. ► DNA binding and cleavage (oxidative and hydrolytic) experiments were performed. ► Complexes exhibit high rate of cleavage activity. ► Rate constants for the hydrolysis of phosphodiester bond were determined as 2.80 h−1 and 2.11 h−1 for 1 and 2, respectively. They amount to an impressive rate enhancement of (0.58–0.77) × 108 compared to non-catalyzed DNA cleavage.