Fonctionnalisation enzymatique de chitosane par des composés phénoliques : évaluation des propriétés biologiques et physico-chimiques de ces nouveaux biopolymères

Abstract : Oxidation of ferulic acid and its ester (ethyl ferulate) by Myceliophtora thermophila laccase has been studied in aqueous medium under mild experimental conditions (30°C and pH 7.5) as a green process to synthesize natural neo-molecules. Enzymatic oxidation led to colored and colorless intermediaries for ferulic acid and ethyl ferulate, respectively. Additionally, ethyl ferulate was oxidized faster than ferulic acid. This procedure has led to dimeric major products with MM = 443 g/mol and MM = 386 g/mol for ethyl ferulate and ferulic acid, respectively. New synthesized molecules demonstrated important antioxidants properties with weak antibacterial and cytotoxic properties. With insoluble chitosan particles in the reaction medium, laccase was protected from inhibition due to oxidation products and the polymerization degree of these products was checked. In addition, the oxidation products reacted with the free NH2 groups forming covalent bonds of Schiff base type (C=N) at C-2 region. The majority of the oxidation products grafted onto chitosan was of dimeric form. This procedure led to colored and colorless chitosans by ferulic acid and ethyl ferulate, respectively, with new properties due to grafting of phenolic compounds. These chitosan derivatives presented interesting functional properties such as antioxidant, physico-chemical (thermal stability) and biological (cell adhesion) as well as the preservation of antibacterial properties of native chitosan
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Abdulhadi Aljawish. Fonctionnalisation enzymatique de chitosane par des composés phénoliques : évaluation des propriétés biologiques et physico-chimiques de ces nouveaux biopolymères. Alimentation et Nutrition. Université de Lorraine, 2013. Français. ⟨NNT : 2013LORR0089⟩. ⟨tel-01749864⟩

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