Dihydrochalcone-derived polyphenols from tea crab apple (Malus hupehensis) and their inhibitory effects onα-glucosidase in vitro.
Food Funct. 2019 May 22 ;10(5):2881-2887. PMID: 31070208
Three dihydrochalcone-derived polyphenols, huperolides A-C (1-3), along with thirteen known compounds (4-16) were isolated from the leaves of Malus hupehensis, the well-known tea crab apple in China. Their chemical structures were elucidated by extensive spectroscopic analysis including NMR (HSQC, HMBC, 1H-1H COSY and ROESY), HRMS and CD spectra. Huperolide A is a polyphenol with a new type of carbon skeleton, while huperolides B and C are a couple of atropisomers, which were isolated from natural sources for the first time. The antihyperglycemic effects of the isolated compounds were evaluated based on assaying their inhibitory activities againstα-glucosidase. As a result, phlorizin (4), 3-hydroxyphloridzin (5), 3-O-coumaroylquinic acid (12) and β-hydroxypropiovanillone (15) showed significant concentration-dependent inhibitory effects on α-glucosidase. Therefore, those compounds might be responsible for the antihyperglycemic effect of this herb, and are the most promising compounds to lead discovery of drugs against diabetes.