Novel tetradentate Schiff base zinc(II) complex as a potential antioxidant and cancer chemotherapeutic agent: Insights from the photophysical and computational approach

Abstract

In this study a new N4 Schiff base ligand (SB) was synthesized via condensation reaction of 3,4-diaminobenzophenone with diacetyl monoxime in 1:2 M ratio. Moreover, the synthesization and characterization of its zinc (II) complex was carried out through elemental analysis, FT-IR, 1H NMR, UV–Vis spectroscopies and molar conductance. Afterwards we scrutinized the above obtained complex to determine its potential anticancer activity against MCF-7 cell line through MTT test, reducing the viable cell numbers to 11% of the control samples after exposure for 72 h. In order to specify its in vitro antioxidant activity, the Zn(II) complex was evaluated, as a radical scavenger, versus 1,1-diphenyl-2-picrylhydrazyl radicals (DPPH). Data obtained from the above assay revealed that Zn(II) complex demonstrated limited (IC50 = 239.5 mg L−1) antioxidant activity in comparison with ascorbic acid. For the purpose of investigating the complex-model proteins binding, human serum albumin (HSA) and β-lactoglobulin (β-LG), we used biophysical methods and molecular modeling. Experimental results showed that the two systems demonstrated identical interactions (hydrogen bonding and Van der Waals forces). But the β-LG demonstrated a much firmer binding affinity to Zn(II) complex than HSA (Kb ∼ 0.67 (±0.10) × 104 M−1 for HSA-Zn complex and 6.45 (±0.15) × 104 M−1 for β-LG-Zn complex). According to the molecular modeling analysis, the Zn(II) complex develops bonds to the remnants that exist in the subdomain IIA of HSA and site A of β-LG.