Exploring the phytochemicals and inhibitory effects against α-glucosidase and dipeptidyl peptidase-IV in Chinese pickled chili pepper: Insights into mechanisms by molecular docking analysis

The present work investigated the effect of 90 days' traditional fermentation on phytochemicals and inhibition towards α-glucosidase and dipeptidyl peptidase-IV (DPP-IV) of pickled chili pepper, and clarified their possible mechanisms based on molecular docking analysis. The results show that traditional fermentation significantly enhanced the inhibition for α-glucosidase but reduced the inhibitory effects towards DPP-IV (P < 0.05), especially fermented for 42 days. In pickled chili peppers, a total of 12 phytochemical compounds were characterized and quantified, of which kaempferol-3-O-rutinoside, kaempferol-3-O-glucoside, apigenin, luteolin, and luteolin glycosides increased significantly after fermentation (P < 0.05). Among the compounds, luteolin showed the highest inhibition against α-glucosidase and isorhamnetin-3-O-glucoside exhibited the strongest inhibition capacity towards DPP-IV. Molecular docking results indicated luteolin, apigenin, and isorhamnetin-3-O-glucoside could effectively interact with crucial amino acid residues of α-glucosidase, while isorhamnetin-3-O-glucoside and isoschaftoside could effectively interact with the key amino acid residues of DPP-IV.