Antidiabetic potential of Catechu via assays for a-glucosidase, a-amylase, and glucose uptake in adipocytes

Zhang, Kun

JOURNAL OF ETHNOPHARMACOLOGY

2022

291

Zhang, YM

Ethnopharmacological relevance: Catechu is the dry water extract of barked branches or stems from Senegalia catechu(L. F.)P. J. H. Hurter & Mabb, which is used as a hypoglycemic regulator in recent researches. Potential anti-hyperglycemic components and the putative mechanisms were evaluated in this investigation. Aim of the study: Evaluated the hypoglycemic activity of Catechu via alpha-glucosidase, alpha-amylase inhibition assays, and glucose uptake in 3T3-L1 adipocytes. Materials and methods: The effects of Catechu on alpha-glucosidase, alpha-amylase inhibition assays and glucose uptake experiment were tested after the ethanol extract of Catechu (EE) was sequentially partitioned with petroleum ether (PEE), ethyl acetate (EAE), and n-butanol fractions (NBE). Next, HPLC-MS and traditional Chinese medicine (TCM) database were used to detect and analyze the primary active ingredients presented in hypoglycemic fraction. In addition, in silico molecular docking study was used to evaluate the candidates' inhibitory activity against alpha-glucosidase and alpha-amylase. Results: The results of alpha-glucosidase and alpha-amylase inhibition assays indicated that all fractions, with the exception of PEE, presented significant inhibitory effects on alpha-glucosidase and alpha-amylase. The inhibitory effect of NBE on alpha-glucosidase was similar to the positive control (NBE IC50 = 0.3353 +/- 0.1215 mu g/mL; Acarbose IC50 = 0.1123 +/- 0.0023 mu g/mL). Furthermore, the inhibitory kinetics of alpha-glucosidase revealed that all fractions except for PEE belong to uncompetitive type. In silico molecular docking analysis showed that the main compositions of NBE ((-)-epicatechin, cyanidin, and delphinidin) possessed superior binding capacities with alpha-glucosidase (3WY1 AutoDock score: 4.82 kcal/mol;-5.59 kcal/mol;-5.63 kcal/mol) and alpha-amylase (4GQR AutoDock score: 4.80 kcal/mol;-5.89 kcal/mol;-4.26 kcal/mol), respectively. The results of glucose uptake experiment indicated that EE, PEE, EAE, and NBE without significant promotion effect on glucose uptake rate of 3T3-L1 adipocytes (P > 0.05). Conclusion: This study revealed that the hypoglycemic effect of Catechu might be related to the inhibitory effects of phenols on digestive enzymes (alpha-glucosidase and alpha-amylase), and the possible active phenols were (-)-epicatechin, cyanidin, delphinidin and their derivatives, which provided scientific evidences for Catechu's traditional use to treat T2DM.