New aryl-chitosan derivatives with strong antioxidant properties by chemoenzymatic modification.

Boeriu, C. (Speaker), Marinella van Leeuwen (Contributor), van den Broek, B. (Contributor), Frissen, G. (Speaker)

Activity: Talk or presentationOral presentationAcademic

Description

Oral presentation, abstract and conference paper
Chitosan, the N-deacetylated derivative of chitin, is a biocompatible, biodegradable and nontoxic natural material, with inherent antimicrobial properties imparted by its specific structure and reactive groups distribution. Antibacterial, antifungal and insecticidal activity of chitosan has been demonstrated in numerous studies. However, the applicability of chitosan in aqueous solutions is limited by its cationic nature in acidic media and the lack of solubility in water and in organic solvents.
This paper reports the synthesis of novel hydroxyaryl-chitosan derivatives with increased solubility and pH-independent bioactive properties.
Laccase, a multinuclear copper-containing oxidase, that is able to oxidise a wide range of phenolic compounds, was used to catalyse the oxidation of phenolic acids to the corresponding quinones, which were further reacting in situ with the nucleophilic amino group of the glucosamine building blocks of chitosan, via a Michael addition reaction. Using this approach, various phenolic acids, e.g. 3-(4-hydroxyphenyl) propionic acid (HPPA), caffeic acid (CA) and ferulic acid (FA), and low molecular weight lignin oligomers (LMW-lignin) were covalently bound to chitosan and hydroxypropyl-chitosan, in acetone/water mixtures containing 50% vol. acetone. FT-IR, 1H-NMR and 2D HSQC-NMR confirmed the formation of new chitosan derivatives. The synthesis was optimized to obtain products with a higher degree of modification. The hydroxyaryl-chitosan derivatives showed strong radical scavenging activity and were able to form hydrogels in water.
In conclusion, laccase-mediated grafting of phenolic compounds to chitosan produces novel materials with enhanced bioactive properties and potential application as antimicrobial and antioxidant agents in food, medical, cosmetic and textile industries.
Period3 Jun 20187 Jun 2018
Event title17<sup>th</sup> Polymer and Organic Chemistry Conference
Event typeConference
LocationPalavas Les Flots, France
Degree of RecognitionInternational