Inhibitory potential of phenylpropanoid glycosides from Ligustrum purpurascens Kudingcha against α‐glucosidase and α‐amylase in vitro

The leaves of Ligustrum purpurascens are used in a Chinese traditional tea called small‐leaved kudingcha, which is rich in phenylpropanoid glycosides (PPGs) and has many beneficial properties. Two critical exoacting glycoside hydrolase enzymes (glucosidases) involved in carbohydrate digestion are α‐glucosidase and α‐amylase. We investigated the properties of PPGs from L. purpurascens for inhibiting α‐amylase and α‐glucosidase activity in vitro and found IC₅₀ values of 1.02 and 0.73 mg mL^?1, respectively. The patterns of inhibiting both α‐amylase and α‐glucosidase were mixed‐inhibition type. Multispectroscopy and molecular docking studies indicated that the interaction between PPGs and α‐amylase and α‐glucosidase altered the conformation of enzymes, with binding at the site close to the active site of enzymes resulting in changed enzyme activity. Our studies may help in the further health use of small‐leaved kudingcha.