Inhibiting Effect of Cleistocalyx operculatus Buds' Extract (DMC) on Pancreatic Lipase

To investigate the inhibitory activity and interaction between DMC and pancreatic lipase, the pNPB was selected as the substrate to investigate the inhibition effect of DMC on pancreatic lipase. The interaction between DMC and pancreas lipase (PL) was also studied by ultraviolet spectroscopy, fluorescence spectroscopy and molecular docking. Pancreatic lipase inhibition assay showed that DMC exhibited competitive inhibitor against pancreatic lipase with IC₅₀ value of 50.01±3.56 μmol/L. The interaction mechanisms between DMC and pancreatic lipase were studied by fluorescence spectra. Experimental results showed that DMC quenched the fluorescence of pancreatic lipase mainly through dynamic quenching mode while increasing the DMC concentration. The synchronous fluorescence spectra and three-dimensional fluorescence spectroscopy indicated that pancreatic lipase microenvironment was not changed by DMC. The thermodynamic parameters ΔG<0 showed that the combination was a spontaneous reaction, and ΔH<0, ΔS<0 showed that the main forces were hydrogen bond or van der Waals force. Molecular docking studies further verified the above results. Thus, DMC has potential as a PL inhibitor.