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Indazole Schiff bases were synthesized 1–24 and structurally characterized by different spectroscopic techniques such as EI-MS, HREI-MS, 1H- and 13C-NMR. Stereochemistry of azomethine moiety in synthesized compounds was confirmed by 2D-NOESY. Among the twenty-four compounds, fourteen compounds 1–5, 7, 9–14, 17, and 20 are structurally new. Compounds 1–24 were screened for in vitro α-glucosidase enzyme inhibitory activity. All compounds were In vitro α-glucosidase inhibitory assay results identified a number of molecules including 1, 2, 4, 7, 9, 10, 12, 13, 18, 19, 21, and 23 as potent α-glucosidase inhibitors with IC50 values 9.4 ± 0.1 to 303.7 ± 0.1 μM as compared to the standard acarbose (IC50 = 750 ± 10 µM). Compound 1 (IC50 = 9.43 ± 0.1 µM) was found to be the most potent molecule of this library. Kinetic studies on most active compound 1 suggested the competitive inhibition mechanism. In silico studies indicated the interaction details between analogs (ligands) and active site of α-glucosidase enzyme.

Inhibition of α-glucosidase enzyme is of prime importance for the treatment of diabetes mellitus (DM). Apart of many organic scaffolds, pyridine based compounds have previously been reported for wide range of bioactivities. The current study reports a series of pyridine based synthetic analogues for their α-glucosidase inhibitory potential assessed by in vitro, kinetics and in silico studies. For this purpose, 2-amino-4-aryl-6-(phenylthio)pyridine-3,5-dicarbonitriles 1–28 were synthesized and subjected to in vitro screening. Several analogs, including 1–3, 7, 9, 11–14, and 16 showed many folds increased inhibitory potential in comparison to the standard acarbose (IC50 = 750 ± 10 µM). Interestingly, compound 7 (IC50 = 55.6 ± 0.3 µM) exhibited thirteen-folds greater inhibition strength than the standard acarbose. Kinetic studies on most potent molecule 7 revealed a competitive type inhibitory mechanism. In silico studies have been performed to examine the binding mode of ligand (compound 7) with the active site residues of α-glucosidase enzyme.