In-vitro binding analysis and inhibitory effect of capsaicin on lipase

Abstract Capsaicin is the main active ingredient in chilis. This study selected capsazepine as a comparative model and revealed the binding mechanism and inhibitory effect of capsaicin on lipase in vitro. Electrochemical results showed capsaicin has a moderate affinity to lipase with a 7.413 × 104 L/mol binding constant, which is higher than capsazepine (3.388 × 104 L/mol). Structural analysis displayed that capsaicin/capsazepine caused a slight disturbance (less than 1%) to the secondary structure of lipase. The capsaicin binding epitope on the lipase was characterized by nuclear magnetic resonance. H47, H48 and H49 were the protons mainly involved in the interaction. In the comparison model, the H27 and H26 were involved in the capsazepine-lipase system. Hydrogen proton binding epitope analysis combined with molecular docking showed the main elements involved in the binding details. Enzyme kinetics results showed that capsaicin could inhibit the activity of lipase, resulting in a decrease in its ability to hydrolyze the substrate varying hydrolysis rate from 0% to 33.33% in different capsaicin concentrations. The biological model in vitro established in this study will support the development of weight-loss-related functional foods.