Diastereomer selectivity in the degradation of a lignin model compound of the arylglycerol β-aryl ether type by white-rot fungi

Mixtures of about equal amounts of the diastereomers of arylglycerol beta-aryl ether 1-(3,4-dimethoxyphenyl)-2-(2-methoxyphenoxy)-1,3-propanedinl (1) were added to cultures of Trametes versicolor, Phanerochaete chrysosporium, and Pycnoporus cinnabarinus. Samples taken from the fungal cultures were analyzed with respect to the fraction of I degraded, the erythro:threo ratio in the remaining 1, and the product profile, using HPLC and UV-diode array detector. The P. cinnabarinus cultures exhibited laccase activity and partially decolorized Remazol Brilliant Blue R (RBBR), but they did not degrade I under the conditions studied. Cultures of T versicolor and P. chrysosporium preferentially degraded the threo isomer of 1. This is consistent with the fact that the product profiles showed larger amounts of threothan erythro-veratrylglycerol. The results can be discussed in relation to the diastereomer selectivity of various oxidants implicated in lignin degradation by white-rot fungi. Preferential degradation of the threo isomer of arylglycerol beta-aryl ethers is not in agreement with the action of Fenton's reagent, since this reagent does not exhibit any stereo preference. (C) 2008 Elsevier Inc. All rights reserved.