Abstract: Schaftoside purified from the ethanol extract of Phyllostachys edulis shoot processing residues by gel permeation chromatography (GPC) was characterized structurally, and its inhibitory effect against pancreatic lipase (PL) was analyzed by enzymatic kinetics, ultraviolet (UV) spectroscopy, fluorescence spectroscopy, and molecular docking. The results showed that in the tested concentration range, schaftoside had a potent inhibitory effect on PL with half maximum inhibitory concentration (IC50) value of (76.3 ± 0.12) μg/mL in a reversible competitive manner. The fluorescence spectra indicated that schaftoside statically quenched the intrinsic fluorescence of PL with a binding constant (Ka) of 1.13 × 104 L/mol (at 293 K) and one binding site. The thermodynamic parameters showed that schaftoside could spontaneously combine with PL through hydrogen bonds and Van Der Waals force to form a stable complex. The synchronous fluorescence and 3D fluorescence spectra unveiled that schaftoside resulted in a red shift in the fluorescence emission wavelength of tyrosine (Tyr) and tryptophan (Trp) residues in PL and a decline in the quenching intensities, leading to enhanced microenvironmental polarity, decreased hydrophobicity, and increased hydrophilicity. Furthermore, molecular docking demonstrated that the carbonyl group in the C ring of schaftoside could combine with PL’s active sites including His264 through hydrogen bonds, hydrophobic force, and Van der Vaals’ force. Our findings provide a theoretical basis for the development of lipid-lowering functional foods based on P. edulis shoot extract.

Key words: Phyllostachys edulis shoot processing residues; schaftoside; pancreatic lipase; competitive inhibition; molecular docking