Acteoside: a lipase inhibitor from the Chinese tea Ligustrum purpurascens kudingcha.

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=1.88×10(4)lmol(-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.