A paramagnetic oxalato-bridged binuclear copper(II) complex as an effective catalase inhibitor. Spectroscopic and molecular docking studies

A binuclear oxalato-bridged Cu complex formulated as [mu-(ox){Cu(Mebpy) (NO3) (H2O)}(2)] (where Mebpy is 5,5'-dimethyl-2,2'-dipyridyl and ox is oxalate) was synthesized through an environment-friendly reaction under ultrasound irradiation. This complex was selected to investigate its molecular interactions with bovine liver catalase (BLC) using experimental and molecular modeling methods. The experimental results demonstrated that, the enzymatic activity of BLC decreased to 34.6% when the concentration of the above complex is equal to 9.0 x 10(-5) M. The fluorescence results showed that Cu complex could bind with BLC with a relatively strong affinity (K-b = 2.61 and 2.67 x 10(7) M-1 at 300 and 310 K, respectively). Due to Cu complex interactions, the intrinsic fluorescence of the BLC was quenched by a static quenching mechanism and hydrogen bonds and van der Waals forces were the main active forces in the interaction process. The results of molecular modeling were in good agreement with the experimental data and showed that there is one binding site for Cu complex on BLC. Also, the in vitro antioxidant activity of the Cu complex was evaluated against 1,1-diphenyl-2-picrylhydrazyl radicals (DPPH.). The obtained results showed that Cu complex presented moderate antioxidant activity (IC50 = 25 mg L-1) in comparison with ascorbic acid. (C) 2020 Elsevier B.V. All rights reserved.