Abstract: In order to investigate the application value of morin as a pancreatic lipase inhibitor, we conducted in vitro and in vivo tests to assess its hypolipidemic activity and mechanism of action in this study. The results showed that morin functioned as a reversible competitive pancreatic lipase inhibitor with a half maximal inhibitory concentration value of (0.42 ± 0.02) mg/mL. Morin interacted with characteristic amino acid residues in the active center of pancreatic lipase through hydrophobic forces, hydrogen bonding, and π-π stacking, resulting in static quenching of the enzyme’s fluorescence. Meanwhile, morin altered its secondary structure, leading to decreased relative content of α-helix and increased relative content of β-sheet and ultimately inhibiting the activity of pancreatic lipase. Notably, morin and the positive control drug orlistat were both competitive inhibitors of pancreatic lipase. The combined use of these two inhibitors showed an additive effect at low concentrations of orlistat but antagonistic effect at high concentrations of orlistat. Morin inhibited the rapid rise of triglyceride in the blood of mice within 6 h following oral ingestion of lard and its effect was not significantly different from that of orlistat. This indicates that morin could reduce fat decomposition and absorption by inhibiting the activity of pancreatic lipase, thereby exerting hypolipidemic effects. The findings of this study provide a theoretical basis for the in-depth development of morin-rich lipid-lowering foods.

Key words: morin; pancreatic lipase; inhibitory activity; action mechanism; triglyceride