Phenyl propenoic side chain degradation of ferulic acid by Pycnoporus cinnabarinus - elucidation of metabolic pathways using [5-H-2]-ferulic acid

The white-rot fungus Pycnoporous cinnabarinus (DMS-1184) was submerged cult ured for 22 days under controlled conditions in a bioreactor. After 6, 9, a nd 15 days of culture the growth medium was supplemented with [5-H-2]-label led ferulic acid (I). The major phenolic compounds identified labelled were four lignans, the methyl esters of ferulic (I) and vanillic acid (VIII), ( E)-coniferyl aldehyde (II), (E)-coniferyl alcohol (III), vanillic acid (VII I), vanillin (IX) and vanillyl alcohol (X). The detection of considerable a mounts of labelled 4-hydroxy-3-methoxyacetophenone (VII) in the late growth phase suggested the increasing formation and decarboxylation of free 4-hyd roxy-3-methoxybenzoylacetic acid (VI) and, thus, a beta -oxidation-like deg radation of ferulic acid (I) or its methyl ester to vanillic acid (VIII). 4 -Hydroxy-3-methoxybenzoyl acetic acid methyl ester (VI) and 3-hydroxy-(4-hy droxy-3-methoxyphenyl)-propanoic acid methyl eater (V) were synthesised and then identified as metabolites in the culture medium. The fungal degradati on of the phenyl propenoic side chain of ferulic acid (I), a principal key step of lignin decomposition, appeared to proceed analogous to fatty acids. (C) 2001 Elsevier Science B.V. All rights reserved.