Trichlorohydroxyquinone

Hancock, James; Morrell, Charles E.; Rhum, David

doi:10.1016/s0040-4039(00)70943-9

Cited by 25 publications

(17 citation statements)

References 2 publications

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“…The possibility that peroxidases might catalyze such dechlorinations was noted by Saunders and Stark (1967), who were, however, unable to detect 2,6dichloro-p-benzoquinone as a product when 2,4,6-trichlorophenol was incubated for three days with turnip peroxidase and H202. Chloroquinones have been reported to be unstable in water (Hancock et al, 1962;Saunders & Stark, 1967), and we also have observed that 0.1 mM aqueous solutions of 2,6-dichloro-p-benzoquinone and 2,3,5,6-tetrachloro-pbenzoquinone develop a purple color with concomitant disappearance of the quinones (as determined by HPLC, data not shown) within ca. 1 h. Our success in identifying the chloroquinones as products is probably attributable to short reaction times (<20 min) and immediate derivatization.…”

Section: Discussionsupporting

confidence: 62%

The oxidative 4-dechlorination of polychlorinated phenols is catalyzed by extracellular fungal lignin peroxidases

Hammel¹,

Tardone²

1988

Biochemistry

188

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The extracellular lignin peroxidases (ligninases) of Phanerochaete chrysosporium catalyzed HzOz-dependent spectral changes in several environmentally significant polychlorinated phenols: 2,4-dichloro-, 2,4,5-trichloro-, 2,4,6-trichloro-, and pentachlorophenol. Gas chromatography/mass spectrometry of reduced and acetylated reaction products showed that, in each case, lignin peroxidase catalyzed a 4-dechlorination of the starting phenol to yield a p-benzoquinone. The oxidation of 2,4-dichlorophenol also yielded a dechlorinated coupling dimer, tentatively identified as 2-chloro-6-(2,4-dichlorophenoxy)-p-benzoquinone. Experiments on the stoichiometry of 2,4,6-trichlorophenol oxidation showed that this substrate was quantitatively dechlorinated to give the quinone and inorganic chloride. Hz'*O-labeling experiments on 2,4,6trichlorophenol oxidation demonstrated that water was the source of the new 4-OXO substituent in 2,6-dichloro-p-benzoquinone. Our results indicate a mechanism whereby lignin peroxidase oxidizes a 4-chlorinated phenol to an electrophilic intermediate, perhaps the 4-chlorocyclohexadienone cation. Nucleophilic attack by water and elimination of HCl then ensue at the 4-position, which produces the quinone. Lignin peroxidases have previously been implicated in the degradation by Phanerochaete of several nonphenolic aromatic pollutants [cf. Haemmerli, S. D., Leisola, M. S.

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Section: Discussionsupporting

confidence: 62%

The oxidative 4-dechlorination of polychlorinated phenols is catalyzed by extracellular fungal lignin peroxidases

Hammel¹,

Tardone²

1988

Biochemistry

188

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“…A new product was detected by HPLC whose UV-visible spectrum in phosphate buffer at pH 7 exhibited a strong absorption at 293 nm and a broad one at 530 nm. This spectrum is identical to that of an authentic sample of TCHQ obtained from tetrachloro-1,4-benzoquinone under highly basic conditions (8). This product was then isolated from a large-scale incubation and purified by TLC, but the hydroxyquinone could not be characterized by mass spectrometry because of its instability during this analysis.…”

Section: Resultssupporting

confidence: 54%

Metabolism of polychlorinated phenols by Pseudomonas cepacia AC1100: determination of the first two steps and specific inhibitory effect of methimazole

et al. 1995

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Resting cells of 2,4,5-trichlorophenoxyacetic acid-grown Pseudomonas cepacia AC1100 metabolize both dichlorophenols, such as 2,4-dichlorophenol, 2,6-dichlorophenol, 3,4-dichlorophenol, and 3,5-dichlorophenol, and more highly substituted phenols, such as 2,4,6-trichlorophenol and pentachlorophenol, to the corresponding chlorohydroquinones. The first hydroxylation occurs in the para position of the phenol regardless of whether this position is replaced by a chlorine substituent. The first evidence leading to the characterization of para-hydroxylase as a flavin-containing enzyme is provided by the inhibitory effect of methimazole, an alternate substrate for this monooxygenase, on the degradative ability of the strain. In a second step, with tetrachlorohydroquinone, trichlorohydroxyquinone was isolated and completely characterized. Trichlorohydroxyquinone was also obtained from tetrachloroquinone. Incubation of the cells in the presence of an external source of NADPH prevents the further degradation of tetrachlorohydroquinone, suggesting that the quinone derived from the two-electron oxidation of the hydroquinone is more likely the substrate for the second hydroxylation.

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“…These results indicate that the major reaction product between TCBQ and H 2 O 2 was probably the ionic form of TrCBQ-OH (peak clusters at m/z 227). This was further confirmed by comparing with the authentic TrCBQ-OH synthesized according to the published method (10), which showed the same ESI-MS profile (Fig. 3C) and the same retention time in HPLC (see Materials and Methods).…”

Section: The Major Reaction Product Between Tcbq and H2o2 Was Identifsupporting

confidence: 63%

Molecular mechanism for metal-independent production of hydroxyl radicals by hydrogen peroxide and halogenated quinones

Zhu

Kalyanaraman

Jiang

2007

Proc. Natl. Acad. Sci. U.S.A.

162

132

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We have shown previously that hydroxyl radicals (HO • ) can be produced by H 2 O 2 and halogenated quinones, independent of transition metal ions; however, the underlying molecular mechanism is still unclear. In the present study, using the electron spin resonance secondary radical spin-trapping method, we found that tetrachloro-1,4-benzoquinone (TCBQ), but not its corresponding semiquinone anion radical, the tetrachlorosemiquinone anion radical (TCSQ •؊ ), is essential for HO • production. The major reaction product between TCBQ and H 2O2 was identified by electrospray ionization quadrupole time-of-flight mass spectrometry to be the ionic form of trichlorohydroxy-1,4-benzoquinone (TrCBQ-OH), and H 2O2 was found to be the source and origin of the oxygen atom inserted into the reaction product TrCBQ-OH. On the basis of these data, we propose that HO • production by H2O2 and TCBQ is not through a semiquinone-dependent organic Fenton reaction but rather through the following mechanism: a nucleophilic attack of H 2O2 to TCBQ, forming a trichlorohydroperoxyl-1,4-benzoquinone (TrCBQ-OOH) intermediate, which decomposes homolytically to produce HO • . This represents a mechanism of HO • production that does not require redox-active transition metal ions.ESR spin-trapping ͉ tetrachloro-1,4-benzoquinone ͉ tetrachlorosemiquinone anion radical ͉ Fenton reaction T he hydroxyl radical (HO • ) has been considered to be one of the most reactive oxygen species produced in biological systems. It has been shown (1-4) that HO • can cause DNA, protein, and lipid oxidation. One of the most widely accepted mechanisms for HO • production is through the transition metalcatalyzed Fenton reaction (where ''Me'' represents a transition metal, such as iron or copper) (1-4):[ Reaction 1]We reported previously (5, 6) that, by using the salicylate hydroxylation assay and electron spin resonance (ESR) spintrapping methods, HO • can be produced by H 2 O 2 and halogenated quinones independent of transition metal ions; however, the underlying molecular mechanism is still unclear. On the basis of our experimental results, a unique mechanism was proposed for HO • production by H 2 O 2 and halogenated quinones.

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Trichlorohydroxyquinone

Cited by 25 publications

References 2 publications

The oxidative 4-dechlorination of polychlorinated phenols is catalyzed by extracellular fungal lignin peroxidases

The oxidative 4-dechlorination of polychlorinated phenols is catalyzed by extracellular fungal lignin peroxidases

Metabolism of polychlorinated phenols by Pseudomonas cepacia AC1100: determination of the first two steps and specific inhibitory effect of methimazole

Molecular mechanism for metal-independent production of hydroxyl radicals by hydrogen peroxide and halogenated quinones

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