4-Methylumbelliferyl oleate is a fluorescent substrate for lipases (Ex/Em=320/450 nm), which can be cleaved by lipase and can be used to measure pancreatic inhibitory activity.

Pancreatic lipase inhibitory activity was assessed by employing 4-Methylumbelliferyl (4-MU) oleate as the substrate. The assay mixture contained 0.1 mM 4-MU oleate (50 µL), McIlvaine buffer (20 µL of 0.1 M citrate-Na2HPO4, pH 7.4), and the test sample (5 µL). This was followed by the addition of porcine pancreatic lipase (25 µL), adjusting the total volume to 0.1 mL. Post incubation at 37℃ for 10 minutes, lipase-catalyzed liberation of 4-MU was quantified using fluorescence multi-detection reader at excitation and emission wavelengths of 320 nm and 450 nm, respectively [1].

4-Methylumbelliferyl (4-MU) oleate as a substrate to measure the inhibitory activity of compounds on pancreatic lipase
a. Reagent preparation: The reaction mixture includes 50 µL of 0.1 mM 4-MU oleate, 20 µL of McIlvane buffer (0.1 M citric acid-Na2HPO4, pH 7.4) and 5 µL of sample solution.
b. Operation steps:
1. Add 25 µL of porcine pancreatic lipase to the reaction mixture and adjust the total volume to 0.1 mL.
2. After the mixture is incubated at 37°C for 10 minutes, the amount of 4-MU released by lipase is measured by using a fluorescence multifunctional detector at an excitation wavelength of 320 nm and an emission wavelength of 450 nm.