2.3.2. Pancreatic Lipase Inhibition in Vitro Assay

The pancreatic lipase inhibition rate was determined according to the method proposed by Prados et al. [33] with some modifications. Dissolved p-nitrophenyl acetate in DMSO to prepare a 50 mM stock solution, then diluted to 10 mM with distilled water. Porcine pancreatic lipase was dissolved in water to prepare a solution with a concentration of 10 mg/mL, and then centrifuged at 13,000 rpm for 5 min. The total volume of the entire reaction system is 0.2 mL, and the composition was as follows: 0.02 mL extract, 0.02 mL enzyme solution, 0.14 mL Tris buffer (pH 7.4), 0.02 mL substrate solution. The absorbance valued of the released p-nitrophenol was measured at 405 nm. The inhibition rate of pancreatic lipase was calculated according to the following formula:

where Amax is the absorbance of the solution without any peptide (the maximum activity of the enzyme), A_S is the absorbance of the enzyme-containing solution after adding peptides, and A_So is the absorbance of sample solution without enzyme.