Diacetyl Monoxime‐Based N∩N Donor Schiff Base and Its Zn(II) Complexes. In Vitro and In Silico Analysis

ABSTRACT Schiff bases are introduced as versatile pharmacophores for the design and development of various bioactive compounds. Oxime‐based Schiff base ligands form an important and flexible class of ligands that have attracted attention due to their wide applications in various fields. Here, novel 3‐(2‐hydroxyphenyl‐imino)butan‐2‐one oxime, ( HPIO ) Schiff base and Zn(II) complexes derived from it, [Zn(bpy)(HPIO)](NO 3 ) 2 , C1 , (bpy = 2,2′‐bipyridine) and [Zn(HPIO) 2 ]Cl 2 , C2 , were synthesized and characterized. Theoretical studies showed that both complexes are reactive and have high pharmacological affinity. Experimental investigations were done to compare some biological properties of the complexes. Antioxidant studies using ·DPPH (2,2‐diphenyl‐1‐picrylhydrazyl) assay presented the following trend: C1 > C2 > HPIO . Considering the importance of the antioxidant enzyme catalase in removing reactive oxygen species (ROS), the binding process of C1 / C2 with catalase was evaluated. Kinetic studies showed that C1 / C2 can inhibit the catalytic performance of catalase by mixed‐type inhibition mechanism. The C1 and C2 quenched the catalase fluorescence emission with static quenching mechanism. The binding affinity to catalase was higher for C1 than C2 ( K b = 1.51 and 0.89 × 10 5 M −1 for C1 and C2 , respectively at 305 K). In C1 / C2 interaction with catalase, which was an exothermic and spontaneous process, hydrogen bonds, van der Waals forces, and hydrophobic interactions played a decisive role and strongly confirmed by molecular docking data. Tracking the structural changes of catalase showed that enzyme undergoes structural changes in the presence of both complexes.