Inhibitory effect of lignin from Canna edulis Ker residues on trypsin: kinetics and molecular docking studies

Background: In our previous study, the lignin extracted from Canna edulis Ker residues showed a strong α-glucosidase inhibitory and α-amylase enhanced activity. Protease activity inhibition may play a key role in disease processes, such as metastasis, tumor invasion, and bacterial colonization. Hence, the inhibitory mechanism of lignin on trypsin was examined in this study, including the interaction type, thermodynamic parameters, structure, reaction site, and molecular docking.

Results: The isolated lignin presented an inhibitory effect on trypsin activity with an IC₅₀ value of 1.35 μM. This inhibition was a mixed linear type with a constant K_i of 3.92 μM. The lignin could bind with the key amino acid residue Ser195 on the active site of the trypsin molecule to inhibit its activity, and the phenolic hydroxyl group and -OH on the β-O-4 structure of the lignin molecule were the major groups bound with trypsin.

Conclusions: These results provided an illustration of the inhibitory effects of Canna edulis residue lignin on protease, which was beneficial for us to understand the possible application of lignin in the food industry as functional foods. This article is protected by copyright. All rights reserved.

Keywords: Canna edulis residue lignin; inhibitory effects; molecular docking; trypsin.