•The inhibition and binding affinities of PPGs for lipase were analyzed.•The hydrogen bond plays an important role in the interaction between PPGs and lipase.•With increasing phenolic hydroxyl groups on PPGs, the interaction increase.•The inhibitory effect of phenolic hydroxyl group is higher at the A-ring than B-ring.The phenolic hydroxyl group in polyphenols is a significant structural feature to for understanding their inhibition of lipase. In this paper, we studied four phenylpropanoid glycosides (PPGs) (acteoside, lipedoside A-I, syringalide A 3′-α-l-rhamnopyranoside and osmanthuside B) with different numbers and positions of the phenolic hydroxyl groups in terms of their inhibition of and affinities for porcine pancreatic lipase. The inhibitory effects on lipase were in the order of acteoside (IC50 = 2.17 ± 0.13 mg/ml) > syringalide A 3′-α-l-rhamnopyranoside (IC50 = 3.87 ± 0.21 mg/ml) > lipedoside A-I (IC50 = 4.27 ± 0.22 mg/ml) > osmanthuside B (IC50 = 23.14 ± 0.51 mg/ml). The order of binding affinity to lipase was acteoside > syringalide A 3′-α-l-rhamnopyranoside > lipedoside A-I > osmanthuside B. The hydrogen bond plays an important role in the interaction between PPGs and lipase. With increasing phenolic hydroxyl groups in PPGs, their binding affinities and inhibition for lipase increased.

•Acteoside from kudingcha showed inhibition of lipase activity.•Acteoside might act as a non-competitive pancreatic lipase inhibitor.•Acteoside altered the conformation of lipase, which changed the enzyme activity.Acteoside is the most abundant and major active component of Ligustrum purpurascens (kudingcha tea). Here, we explored the anti-obesity properties of acteoside by investigating its effect on lipase activity. Characterization of acteoside and lipase by fluorescence spectroscopy, isothermal titration calorimetry and circular dichroism revealed that acteoside might act as a non-competitive lipase inhibitor. Acteoside bound to lipase at Ka = 1.88 × 104 l mol−1. Thermodynamic features suggested that the binding interaction was mainly hydrophobic and the complex was stabilized by hydrogen bonding, with 1:1 interaction of acteoside and lipase. Furthermore, docking results supported experimental findings and revealed hydrogen bonding with Lys271, Leu272 and Thr68 of lipase. This non-covalent bonding between acteoside and lipase alters the molecular conformation of lipase, which decreases the enzyme catalytic activity.

Understanding the interaction of (−)-epigallocatechin-3-gallate (EGCG) and lipase is important for understanding EGCG’s inhibition of lipase. In this paper, the interaction of EGCG and porcine lipase was characterized by fluorescence spectroscopy, circular dichroism (CD), isothermal titration calorimetry, and molecular docking. EGCG might act as a noncompetitive pancreatic lipase inhibiter. EGCG bound to lipase with affinity of Ka = 2.70 × 104 L mol–1. Thermodynamic features suggested that the interaction process was spontaneous, with hydrogen bonds and electrostatic force perhaps primarily responsible for the interaction, with 1:1 interaction of lipase and EGCG. CD studies indicated conformation change of lipase on binding to EGCG. Furthermore, docking results supported experimental findings and revealed hydrogen-bonding interaction with Val21, Glu188, and Glu220. This noncovalent bonding between EGCG and lipase alters the molecular conformation of lipase, which decreases the enzyme catalytic activity. This study will help further understand the antiobesity mechanisms of green tea.