Degradation of biphenyl lignin model compounds by laccase of Trametes versicolor in the presence of 1-hydroxybenzotriazole and heteropolyanion [SiW11VO40]5-

A series of phenolic/non-phenolic biphenyl model compounds mimicking 5-5' type "condensed" lignin substructures were subjected to the oxidation with laccase of Trametes versicolor in the presence of 1-hydroxybenzotriazole (HBT) or [SiW11VO40](5-) (SiW11V) as mediators. Phenolic models suffered a significant degradation in both the laccase-mediator systems (LMS), which was more pronounced, however, in the case of SiW11V-mediated oxidation. This result was explained, at least partially, by HBT decomposition and by the increased extent of competing radical coupling reactions of phenolic models in the HBT-laccase reaction system. The non-phenolic biphenyl model was non-reactive in the presence of SiW11V and degraded substantially in the presence of HBT. The main degradation pathways of lignin model compounds were deduced based on the analysis of the detected oxidation products. (C) 2003 Elsevier Science B.V. All rights reserved.