Degradation of a non-phenolic β-O-4 substructure and of polymeric lignin model compounds by laccase ofCoriolus versicolorin the presence of 1-hydroxybenzotriazole

Abstract

A β-O-4 lignin substructure model compound, 2-(2,6-dimethoxy-4-formylphenoxy)-1,3-dihydroxy-1-(4-ethoxy-3-methoxyphenyl)propane, was oxidized by Coriolus versicolor laccase in the presence of 1-hydroxybenzotriazole to form four products: 2,3-dihydroxy-1-(4-ethoxy-3-methoxyphenyl)propanone, 1-(4-ethoxy-3-methoxyphenyl)-3-hydroxypropanone, 4-ethoxy-3-methoxybenzoic acid, and 2,6-dimethoxy-p-benzoquinone. The results show that three types of the reactions, β-ether cleavage, Cα-Cβ cleavage, and Cα-oxidation are catalyzed by laccase–1-hydroxybenzotriazole couple. Furthermore, depolymerization of a polymeric guaiacyl lignin model compound prepared from [β-14C]coniferyl alcohol was also caused by this system.