Licochalcone A: A lipase inhibitor from the roots of Glycyrrhiza uralensis

In order to develop a functional food and anti-obesity drug through the inhibition of absorption of dietary lipids, we investigated the inhibitory effects on pancreatic lipase of extracts from more than 800 species of herbs in Korea. In this study, licochalcone A was isolated from the ethyl acetate/n-hexane fraction of ethyl acetate extract of the roots of Glycyrrhiza uralensis. Its structure was elucidated by 1H NMR, 13C NMR and HR-EI mass spectroscopy. Licochalcone A substantially inhibited activity with IC50 value of 35 μg/mL (103.4 μM). In an investigation of reversibility, licochalcone A was shown to be reversible to pancreatic lipase. The inhibition mode of licochalcone A was a non-competitive inhibitor, determined by Lineweaver–Burk plot analysis, and Ki value was 11.2 μg/mL (32.8 μM). Furthermore, licochalcone A significantly reduced the production of oleic acid with not only artificial substrate DNPB but natural substrate triolein by pancreatic lipase.