New acetohydrazide-based Schiff base complexes with the ability to enhance catalase activity

Abstract

Due to the wide biological capabilities of Schiff bases, the use of these ligands in the synthesis of metal complexes has been greatly expanded. Here, a new Schiff base ligand N'-3-(hydroxyimino)butan-2-ylidene)acetohydrazide, HIBYA, and its Zn(II) complexes, [Zn(HIBYA)2]Cl2 (C1), [Zn(HIBYA)(bpy)](NO3)2 (C2), and [Zn(HIBYA)(phen)](NO3)2 (C3) (bpy = 2,2′-bipyridine and phen = 1,10-phenanthroline) were synthesized and characterized. The antioxidant properties of the ligand and C1-C3 were evaluated with the help of •DPPH (2,2-Diphenyl-1-picrylhydrazyl) assay and it showed that C1 has more ability to inhibit free radicals. The antioxidant performance of compounds increased as follows: C1 > C3 > C2 > HIBYA. The binding mechanism of C1-C3 with bovine liver catalase (BLC) was also evaluated. The structure and activity of the BLC showed changes in the presence of C1-C3. The activity of the enzyme showed the greatest change in the presence of C1, so that at a concentration of 0.17 μM, C1-C3 improved initial enzyme performance by 68 %, 23 %, and 56 %, respectively. The binding strength of the C1-C3 with BLC was almost similar and with the order of 104 M−1 (Kb = 11.74 × 104 M−1 for C1, 1.23 × 104 M−1 for C2, and 12.58 × 104 M−1 for C3 at 303 K). The mechanism of C1-C3 binding with BLC was similar, the dominant forces in the interaction process were hydrogen bonds and van der Waals forces. Docking studies confirmed the spectroscopic results and predicted the amino acids involved in the interaction.