Three common caffeoylquinic acids as potential hypoglycemic nutraceuticals: Evaluation of α-glucosidase inhibitory activity and glucose consumption in HepG2 cells

The demand for plant-derived antidiabetic nutraceuticals is increasing. In this study, the effects of three common caffeoylquinic acids (CQAs) (chlorogenic acid, isochlorogenic acid A, and cynarin) on alpha-glucosidase activity and glucose consumption in HepG2 cells were systematically compared. Their alpha-glucosidase inhibitory activities followed the order of isochlorogenic acid A > chlorogenic acid > cynarin. The fluorescence analysis indicated that they exerted the inhibitory role by forming the complex with alpha-glucosidase at the molar ratio of 1:1. Isochlorogenic acid A possessed the highest binding capacity, followed by chlorogenic acid and cynarin. The effect of caffeoyl group distribution on the alpha-glucosidase inhibitory activity was clarified by the molecular docking results. In the HepG2 cells, isochlorogenic acid A also showed the best glucose consumption with negligible cytotoxicity, which might be related to its reactive oxygen species scavenging capacity in cells. Our results confirm its potential application as the antidiabetic nutraceutical. Practical applications The hypoglycemic activities of three common CQAs (chlorogenic acid, isochlorogenic acid A, and cynarin) were systemically evaluated in this study. Isochlorogenic acid A exhibited the strongest alpha-glucosidase inhibitory activity and highest glucose consumption in HepG2 cells with low cytotoxicity. The results suggest that isochlorogenic acid A can be used as the potential hypoglycemic nutraceutical in functional foods.