Oxidative degradation of non-phenolic lignin during lipid peroxidation by fungal manganese peroxidase.

A non-phenolic lignin model dimer, 1-(4-ethoxy-3-methoxyphenyl)-2-phenoxypropane-1,3-diol, was oxidized by a lipid peroxidation system that consisted of a fungal manganese peroxidase, Mn(II), and unsaturated fatty acid esters. The reaction products included 1-(4-ethoxy-3-methoxyphenyl)-1-oxo-2-phenoxy-3-hydroxypropane and 1-(4-ethoxy-3-methoxyphenyl)-1-oxo-3-hydroxypropane, indicating that substrate oxidation occurred via benzylic hydrogen abstraction. The peroxidation system depolymerized both exhaustively methylated (non-phenolic) and unmethylated (phenolic) synthetic lignins efficiently. It may therefore enable white-rot fungi to accomplish the initial delignification of wood.