Identification of antidiabetic components from Cyclocarya paliurus

Cyclocarya paliurus (C. paliurus) is a well-known new food resource whose extraction has certain antidiabetic activity. In this study, compounds were prepared from C. paliurus and their antidiabetic activity were further evaluated in vivo and in vitro. Besides, chemical structures of these compounds were analyzed using nuclear magnetic resonance (NMR). The study showed that compounds extracted from C. paliurus showed excellent antidiabetic activity, which was shown in hypoglycemic effect, lipid metabolism regulation, antioxidant enzyme system improvement, insulin sensitivity increasing and repairment of islet cells. Two major antidiabetic compounds were identified, namely quercetin-3-O-β-D-glucuronide-6′-methyl ester (compound 1) and kaempferol-3-O-β-D-glucuronide-6′-methyl ester (compound 2), and compound 1 was firstly discovered in C. paliurus. Compounds 1 and 2 were proved great inhibition in vitro with IC50 values of 48.25 μg/mL, 66.30 μg/mL of α-amylase inhibition and 115.2 μg/mL, 136.8 μg/mL of α-glucosidase inhibition, respectively. Molecular docking analysis proved that compounds can bind to the active sites of enzymes. The results explored the antidiabetic compounds of C. paliurus, which can further help promote development of C. paliurus and enlarge kinds of therapeutic alternatives to antidiabetic recipes.