Degradation of a non-phenolic β-<i>O</i>-4 substructure and of polymeric lignin model compounds by laccase of<i>Coriolus versicolor</i>in the presence of 1-hydroxybenzotriazole

Abstract

A L-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, L-ether cleavage, CK-CL cleavage, and CK-oxidation are catalyzed by laccase^1-hydroxybenzotriazole couple. Furthermore, depolymerization of a polymeric guaiacyl lignin model compound prepared from [L-IR C]coniferyl alcohol was also caused by this system.