Phenylpropanoid glycoside inhibition of pepsin, trypsin and α-chymotrypsin enzyme activity in Kudingcha leaves from Ligustrum purpurascens

•Kudingcha (bitter tea) has been used for health in China for a long time.•Phenylpropanoid glycosides are important ingredients in Kudingcha.•Phenylpropanoid glycosides have a binding effect on digestive enzymes.•Phenylpropanoid glycosides could inhibit digestive enzyme activities.

Phenylpropanoid glycosides (PPGs) are important ingredients in Kudingcha bitter tea from Ligustrum purpurascens, possessing many beneficial properties. Here, we investigated the effect of PPGs on the activity of the digestive enzymes pepsin, trypsin and α-chymotrypsin. Furthermore, we explored the interactions between PPGs and digestive enzymes by a multi-spectroscopic method and docking studies. PPGs could inhibit digestive enzyme activities with a non-competitive pattern of inhibition. PPGs may have a binding effect on these digestive enzymes, changing the polarity and the structure of enzymes, which results in decreased enzyme activity. This description of the effects of PPG inactivation of pepsin, trypsin and α-chymotrypsin helps reveal the potential anti-nutritional property of PPGs.