The Reactions of Hydroxyl Radicals with Aromatic Rings in Lignins, Studied with Creosol and 4-Methylveratrol

Gierer, Josef; Yang, Erquan; Reitberger, Torbjörn

doi:10.1515/hfsg.1992.46.6.495

Cited by 94 publications

(53 citation statements)

References 8 publications

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“…This analogy is reasonable since the main intermediates involved in such reactions are believed to be phenoxy radicals. 20 The phenolic diphenylmethane and a-5 structures, 8 and 13, respectively, were found to be remarkably more reactive than the 5-5 H dicreosol model compound 1, that was degraded by the laccase treatments only in low amounts. The diphenylmethane model 8, which showed the highest reactivity, also showed the highest amount of high molecular weight metabolites, probably arising from radical coupling reactions.…”

Section: Discussionmentioning

confidence: 94%

The early oxidative biodegradation steps of residual kraft lignin models with laccase

Crestini

Argyropoulos

1998

Bioorganic & Medicinal Chemistry

129

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Section: Discussionmentioning

confidence: 94%

The early oxidative biodegradation steps of residual kraft lignin models with laccase

Crestini

Argyropoulos

1998

Bioorganic & Medicinal Chemistry

129

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“…Intracellular hydroxylation was also observed in white rot fungi: Phanerochaete chrysosporium produced 4,5-dichlorocatechol from 3,4-dichlorophenol (5). Aromatic hydroxylation involving chemically generated hydroxyl radicals has been studied with a variety of compounds (10,21,22). From salicylic acid, congeners hydroxylated in ortho and para positions were formed: the generation of 2,3-dihydroxybenzoate and 2,5-dihydroxybenzoate has been used to detect hydroxyl radicals (7,13).…”

Section: Discussionmentioning

confidence: 99%

Hydroxylated Metabolites of 2,4-Dichlorophenol Imply a Fenton-Type Reaction in Gloeophyllum striatum

Schlößer

Fahr

Karl³

et al. 2000

Appl Environ Microbiol

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While degrading 2,4-dichlorophenol, two strains of Gloeophyllum striatum, a basidiomycetous fungus causing brown rot decay of wood, simultaneously produced 4-chlorocatechol and 3,5-dichlorocatechol. These metabolites were identified by comparing high-performance liquid chromatography retention times and mass spectral data with those of chemically synthesized standards. Under similar conditions, 3-hydroxyphthalic hydrazide was generated from phthalic hydrazide, a reaction assumed to indicate hydroxyl radical formation. Accordingly, during chemical degradation of 2,4-dichlorophenol by Fenton's reagent, identical metabolites were formed. Both activities, the conversion of 2,4-[U-14 C]dichlorophenol into 14 CO 2 and the generation of 3-hydroxyphthalic hydrazide, were strongly inhibited by the hydroxyl radical scavenger mannitol and in the absence of iron. These results provide new evidence in favor of a Fenton-type degradation mechanism operative in Gloeophyllum.Basidiomycetous fungi causing brown rot decay of wood play an important role in the carbon cycle. They depolymerize the cellulose component of wood while lignin remains as an amorphous brown residue. In this process, an extracellular Fentontype mechanism, providing hydroxyl radicals via Fe 2ϩ and hydrogen peroxide, has long been implicated (15). However, the potential of species like Gloeophyllum striatum and Gloeophyllum trabeum in the degradation of xenobiotics was explored only recently: two fluoroquinolone antibacterial drugs, polyethylene glycol, and two chlorophenols have been shown to be decomposed (9, 14,23,24). G. striatum produced three remarkable hydroxylated congeners of enrofloxacin, which could also be generated via Fenton's reaction (23). An extracellular 2,5-dimethoxyhydroquinone-driven Fenton reaction in G. trabeum, employed to depolymerize polyethylene glycol, represents the most recent mechanistic evidence (14).Wheat straw cultures of G. striatum catalyzed CO 2 production from the environmental pollutant 2,4-dichlorophenol (2,4-DCP). Moreover, in a defined mineral medium lacking carbon, nitrogen, and phosphate, G. striatum expressed a degradation capacity similar to that shown on wheat straw (9, 23). Here, our aim was to provide further evidence for a Fenton-type reaction in G. striatum by (i) identifying primary metabolites of 2,4-DCP formed by the fungus and in Fenton's reaction as well; (ii) testing for hydroxylation of phthalic hydrazide (PH) giving 3-hydroxyphthalic hydrazide (3-OHPH), which has been postulated to specifically indicate hydroxyl radical formation (1, 2, 19); and (iii) inhibiting the conversion of 2,4-[U-14 C]DCP to 14 CO 2 as well as hydroxylation of PH under conditions antagonizing hydroxyl radical activity. Such data are intended to help to firmly establish the capability of some higher fungi to employ a Fenton-type reaction in the degradation of xenobiotics. This reaction may even take different forms in the few genera investigated so far (13, 14). MATERIALS AND METHODSOrganisms. The source and maintenance of G. str...

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“…Barr and Aust (1994) and Gierer et al (1992) discussed depolymerization and repolymerization of lignin in the presence of hydroxyl radicals, and Goodell et al (1997) suggested that a similar mechanism existed in brown rot when the chelator-mediated Fenton reaction was active. More recent research suggests that brown-rot fungi have a greater ligninolytic capability (Arantes et al 2009aYelle et al 2008Yelle et al , 2011Martinez et al 2011) than previously thought (Agosin et al 1989;Eriksson et al 1990).…”

Section: Lignin Oxidationmentioning

confidence: 99%

Peculiarities of brown-rot fungi and biochemical Fenton reaction with regard to their potential as a model for bioprocessing biomass

Arantes

Jellison

Goodell

2012

Appl Microbiol Biotechnol

284

214

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This work reviews the brown-rot fungal biochemical mechanism involved in the biodegradation of lignified plant cell walls. This mechanism has been acquired as an apparent alternative to the energetically expensive apparatus of lignocellulose breakdown employed by white-rot fungi. The mechanism relies, at least in the incipient stage of decay, on the oxidative cleavage of glycosidic bonds in cellulose and hemicellulose and the oxidative modification and arrangement of lignin upon attack by highly destructive oxygen reactive species such as the hydroxyl radical generated non-enzymatically via Fenton chemistry [Formula: see text]. Modifications in the lignocellulose macrocomponents associated with this non-enzymatic attack are believed to aid in the selective, near-complete removal of polysaccharides by an incomplete cellulase suite and without causing substantial lignin removal. Utilization of this process could provide the key to making the production of biofuel and renewable chemicals from lignocellulose biomass more cost-effective and energy efficient. This review highlights the unique features of the brown-rot fungal non-enzymatic, mediated Fenton reaction mechanism, the modifications to the major plant cell wall macrocomponents, and the implications and opportunities for biomass processing for biofuels and chemicals.

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The Reactions of Hydroxyl Radicals with Aromatic Rings in Lignins, Studied with Creosol and 4-Methylveratrol

Cited by 94 publications

References 8 publications

The early oxidative biodegradation steps of residual kraft lignin models with laccase

The early oxidative biodegradation steps of residual kraft lignin models with laccase

Hydroxylated Metabolites of 2,4-Dichlorophenol Imply a Fenton-Type Reaction in Gloeophyllum striatum

Peculiarities of brown-rot fungi and biochemical Fenton reaction with regard to their potential as a model for bioprocessing biomass

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