A new approach to produce plant antioxidant-loaded chitosan for modulating proteolytic environment and bacterial growth.

This work reports a straightforward approach for incorporation of plant-derived flavonoid-based antioxidants into an intrinsically antimicrobial chitosan platform in order to generate chitosan-based materials suitable for biomedical applications. The novelty of this approach consists in the use of thioacidolysis - a common analytical method for the characterization of proanthocyanidins - to covalently functionalize natural macromolecules such as chitosan with bioactive phenolic moieties. It is known that proanthocyanidins undergo depolymerization in acid medium, where in the presence of nucleophiles they form stable flavan-3-ol derivatives. Based on this reaction, flavan-3-ol moieties from the polyphenol extract of Hamamelis virginiana are incorporated covalently into a previously thiolated chitosan matrix. The phenolics-functionalized chitosan possesses improved antioxidant and antimicrobial properties, and inhibitory efficiency over deleterious wound enzymes in vitro.