title: Oxygenation of 4-alkoxyl groups in alkoxybenzoic acids by Polyporus dichrous.
abstract: The degradation of several alkyl ethers of vanillic acid, of 3-ethoxy-4-hydroxybenzoic acid, and of syringic acid, by the lignin-decomposing fungus Polyporus dichrous included (i) 4-dealkylation (e.g., 3-ethoxy-4-isopropoxybenzoic acid was in part dealkylated to 3-ethoxy-4-hydroxybenzoic acid), (ii) hydroxylation of the 4-alkoxyl groups (e.g., 3-ethoxy-4-isopropoxybenzoic acid was oxidized in part to 2-[4-carboxy-2-ethoxyphenoxy]-propane-1-ol), and (iii) reduction of carboxyl groups (older cultures) (e.g., 3-ethoxy-4-isopropoxybenzoic acid was reduced to 3-ethoxy-4-isopropoxybenzaldehyde and 3-ethoxy-4-isopropoxybenzyl alcohol). Some ethers (e.g., tri-O-methyl gallic acid and glycerol-beta-[4-carboxy-2-ethoxyphenyl]-ether) were not affected. The dealkylations and hydroxylations indicate that the fungus has a relatively nonspecific mechanism for oxygenating various 4-alkoxyl groups of alkoxybenzoic acids; no evidence for oxygenation of 3-alkoxyl groups was obtained. Hydroxylation products were generally degraded further, probably via dealkylation. The vanillic acid and 3-ethoxy-4-hydroxybenzoic acid formed by dealkylations were readily metabolized. Although the isopropyl ether of syringic acid was hydroxylated to 2-(4-carboxy-2, 6-dimethoxyphenoxy)-propane-1-ol, neither this compound nor the parent isopropyl ether was dealkylated; syringic acid itself was only slowly and incompletely metabolized. The relationship of these results to lignin degradation is discussed.
mesh_terms: D001487:Basidiomycota / Q000254:growth & development / Q000378:metabolism*; D001565:Benzoates / Q000378:metabolism*; D055598:Chemical Phenomena; D002621:Chemistry; D002849:Chromatography, Gas; D003470:Culture Media; D003640:Dealkylation; D004987:Ethers / Q000378:metabolism; D006900:Hydroxylation; D008031:Lignin / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D010084:Oxidation-Reduction; D013055:Spectrophotometry, Infrared; D013056:Spectrophotometry, Ultraviolet; D014934:Wood
chemical_list: D001565:Benzoates; D003470:Culture Media; D004987:Ethers; D008031:Lignin