Lignin as functional enzyme inhibitors: Activity, mechanism, and application

Lignin, as a sustainably sourced phenol-containing polymer, is gaining increasing attention for its valorization potential although its currently underused status. Lignin presents a unique crosslinked aromatic structure with an abundance of active groups such as phenolic hydroxyl and carboxyl groups. These groups contribute the interaction of lignin with the active sites of some enzymes, thus inhibiting their activities. Recent studies have demonstrated that lignin can inhibit enzymes such as tyrosinase, α-amylase, trypsin, and α-D-glucosidase, highlighting their potential as functional enzyme inhibitors. Building on this, this review provides a comprehensive analysis of the mechanisms behind lignin's enzyme inhibition and explores its practical applications, particularly in the pharmaceutical, cosmetic, and food industries. By systematically exploring its potential, this study aims to facilitate the transformation of lignin from an industrial by-product into a high-value bioactive material, contributing to sustainable development and innovative industrial applications. • The potential of lignin as an enzyme inhibitor is explored. • The mechanism of lignin as an enzyme inhibitor is identified and described. • The interaction between lignin's functional groups and the enzyme is crucial for inhibition. • The pathways of enhancement of enzyme inhibition by different lignin are analyzed. • The current practical applications of lignin-derived enzyme inhibitors are summarized.