Abstract: This research analyzed the structures of flavonoids extracted from chestnut shells and studied their inhibitory effect on pancreatic lipase as well as the type of inhibition. The flavonoids were extracted with aqueous ethanol as the solvent and purified with AB-8 macroporous resin. The content of the freeze-dried flavonoids was (107.50 ± 1.00) mg/g, and the extraction yield was (5.66 ± 0.05)%. Eight flavonoids were identified from chestnut shells by ultra-performance liquid chromatography-quadrupole/electrostatic field orbitrap mass spectrometry (UPLC-Q-Orbitrap MS). The p-nitrophenol method was used to investigate the inhibitory effect of chestnut shell flavonoids on pancreatic lipase under different reaction conditions. The results showed that chestnut shell flavonoids had a strong inhibitory effect on pancreatic lipase with a half maximal inhibitory concentration (IC50) of 0.074 mg/mL, and resulted in an alkaline shift in the optimum pH of pancreatic lipase. The type of inhibition was measured as noncompetitive inhibition by Lineweaver-Burk plot, with an inhibition constant (Ki) of 53.19 mg/mL. Thus, chestnut shell flavonoids are good pancreatic lipase inhibitors.

Key words: chestnut shells; flavonoids; ultra-performance liquid chromatography-quadrupole/electrostatic field orbitrap mass spectrometry; pancreatic lipase; inhibition