Functionalization of chitosan by laccase-catalyzed oxidation of ferulic acid and ethyl ferulate under heterogeneous reaction conditions

• Published in: Carbohydrate polymers 2012-01, Vol.87 (1), p.537-544
• Main Authors: Aljawish, Abdulhadi, Chevalot, Isabelle, Piffaut, Bernadette, Rondeau-Mouro, Corinne, Girardin, Michel, Jasniewski, Jordane, Scher, Joël, Muniglia, Lionel
• Format: Article
• Language: English
• Subjects: absorbance; antioxidant activity; Antioxidant properties; Applied sciences; biocatalysts; Bioengineering; Biological and medical sciences; Biomaterials; carbon; Chemical and Process Engineering; Chitosan; color; Engineering Sciences; Enzymatic functionalization; Ethyl ferulate; Exact sciences and technology; Ferulic acid; Fourier transform infrared spectroscopy; General and cellular metabolism. Vitamins; laccase; Life Sciences; Medical sciences; Myceliophtora thermophyla laccase; Natural polymers; nuclear magnetic resonance spectroscopy; oxidation; Pharmacology. Drug treatments; phosphates; Physicochemistry of polymers; schiff bases; stable isotopes; Starch and polysaccharides
• ISSN: 0144-8617; 1879-1344
• DOI: 10.1016/j.carbpol.2011.08.016

► Chitosan was functionalized as solid particles with phenolic compounds. ► Phenolic acids were grafted onto chitosan thanks to laccase catalysis. ► Covalent bonds were proved between oxidative products and free amino groups of chitosan. ► Chitosan derivatives presented improved functional properties. ► The grafting, an eco-friendly procedure, is performed in aqueous medium. Chitosan particles were functionalized with ferulic acid (FA) and ethyl ferulate (EF) as substrates using laccase from Myceliophtora thermophyla as biocatalyst. The reactions were performed with chitosan particles under an eco-friendly procedure, in a heterogeneous system at 30°C, in phosphate buffer (50mM, pH 7.5). The FA-chitosan derivative presented an intense yellow-orange color stable while the EF-chitosan derivative was colorless. The spectroscopic analyses indicated that the reaction products bound covalently to the free amino groups of chitosan exhibiting a novel absorbance band in the UV/Vis spectra between 300 and 350nm, at C-2 region by the duplication of C-2 signal in the 13C NMR spectrum, via Schiff base bond (NC) exhibiting novel bands in the FT-IR spectrum at 1640 and 1620cm−1. Additionally, antioxidant capacities of chitosan derivatives showed that the chitosan derivatives presented improved antioxidant properties, especially for FA-chitosan derivative (EC50 were 0.52±0.04, 0.20±0.02mg/ml for DPPH and ABTS+ scavenging, respectively).