Laccase-initiated reaction between phenolic acids and chitosan

• DOI: 10.1016/j.reactfunctpolym.2013.01.005
• Publication Date: 2013-01-16T08:15:35Z
• Authors: Mojca Božič; Janez Štrancar; Vanja Kokol
• Keywords: ABTS; Phenolic acid; Trametes versicolor

Abstract Phenolic acids are known to possess antioxidant activities whilst chitosan is a biocompatible polymer with antibacterial activity against a broad spectrum of bacteria. Merging both types of molecules could therefore provide several potential applications. In this work, antioxidant properties of phenolic acid–functionalized-chitosan were investigated after being prepared from structurally-different phenolic acids (caffeic and gallic acids) and chitosan using the laccase from Trametes versicolor as the reaction initiator. A laccase-mediated oxidation kinetic of phenolic acids was monitored by UV–vis spectroscopy and cyclic voltammetry, as well as spin-trapping electron paramagnetic resonance spectroscopy (ST-EPR). The pH was shown to have a significant effect on the degree of phenolic acid self-polymerization, indicating the involvement of phenolate anions within the formations of coupled polyphenol products, and their functionalities, i.e. antioxidant activity. All the phenolic acid-functionalized-chitosans displayed greatly improved ABTS radical cation scavenging capacities, compared with the untreated chitosan.