New β-carboline derivatives as potential α-glucosidase inhibitor: Synthesis and biological activity evaluation

α-Glucosidase is an important therapeutic target of diabetes mellitus. To find potent α-glucosidase inhibitors, thirty-one β-carboline derivatives containing piperazine moieties (6a∼6u, 7a∼7j) were synthesized and evaluated their α-glucosidase inhibitory activity. Most β-carboline derivatives showed potential α-glucosidase inhibitory activity, especially, compound 7c presented obvious α-glucosidase inhibitory activity (IC50: 8.9 ± 0.2 μM), ∼ 69 folds stronger than acarbose (IC50: 610.7 ± 0.1 μM). Inhibition mechanism and kinetics explained compound 7c to be a reversible and mixed-type inhibitor. CD spectra, 3D fluorescence, and molecular docking were employed to reveal the mechanisms of 7c against α-glucosidase. Cell cytotoxicity assay ascertained low cytotoxicity of 7c.