Novel Bis-Schiff’s base derivatives of 4-nitroacetophenone as potent α-glucosidase agents: Design, synthesis and in silico approach

Bis-Schiff's base derivatives of 4-nitroacetophenone (1-18) were synthesized in good yields by reacting hydrazone of 4-nitroacetophenone with substituted aldehydes and ketones with catalytic amount of acetic acid. The structures of synthesized products (1-18) were deduced with the help of spectroscopic techniques like 1H NMR, 13C NMR and HR-ESIMS. The synthesized bis-Schiff's bases were assessed for their α-glucosidase inhibitory activity where compound 4 (IC50 = 2.79 ± 0.04 µM), 1 (IC50 = 9.76 ± 0.31 µM), 6 (IC50 = 11.37 ± 0.20 µM), 17 (IC50 = 14.10 ± 0.12 µM), 14 (IC50 = 17.21 ± 0.28 µM), and 8 (IC50 = 20.73 ± 0.53 µM), showed a very high potential for inhibition of α-glucosidase. Compounds 11, 15, 16, 2, 18, 7, and 5 showed significant inhibition against alpha-glucosidase with IC50 values 22.98 ± 0.34, 24.45 ± 0.53, 27.31 ± 0.29, 40.56 ± 0.60, 41.58 ± 0.47, 46.53 ± 0.76, and 47.46 ± 0.89 µM, respectively. Furthermore, compound 10 (IC50 = 52.63 ± 0.74 µM), 12 (IC50 = 70.80 ± 3.59 µM), 3 (IC50 = 82.68 ± 0.69 µM), 13 (IC50 = 88.89 ± 4.25 µM), and 9 (IC50 = 94.58 ± 0.86 µM) showed moderate activity towards the inhibition of α-glucosidase enzyme. All these compounds were compared with acarbose (IC50 = 875.75 ± 1.24 µM) as a standard α-glucosidase inhibitor. Molecular docking was used to know the molecular bases of such high activities against α-glucosidase. High docking scores were recorded implying significant interactions between the active compounds and amino acid residues of the active site of α-glucosidase.