Preparation of ethoxyquin salts and their genotoxic and antioxidant effects on human lymphocytes

Błaszczyk, Alina; Skolimowski, Janusz

doi:10.3998/ark.5550190.0008.615

Cited by 4 publications

(1 citation statement)

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“…Ethoxyquin has also been found to stimulate nuclear translocation of Nrf2 protein, and the subsequent increases in gene products that detoxify and eliminate cytotoxic metabolites are useful for treatment of diabetic retinopathy . Among unfavorable side effects, one can mention an inhibitory effect on electron transport in the mitochondrial respiratory chain, a hypothermal effect in rodents, and apoptosis and cytotoxicity and genotoxicity in human lymphocytes. The toxicity of ethoxyquin is an area of ongoing debate.…”

Section: Introductionmentioning

confidence: 99%

Antioxidant Profile of Ethoxyquin and Some of Its S, Se, and Te Analogues

et al. 2007

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6-(Ethylthio)-, 6-(ethylseleno)-, and 6-(ethyltelluro)-2,2,4-trimethyl-1,2-dihydroquinoline-three heavier chalcogen analogues of ethoxyquin-were prepared by dilithiation of the corresponding 6-bromodihydroquinoline followed either by treatment with the corresponding diethyl dichalcogenide (sulfur derivative) or by insertion of selenium/tellurium into the carbon-lithium bond, oxidation to a diaryl dichalcogenide, borohydride reduction, and finally alkylation of the resulting areneselenolate/arenetellurolate. Ethoxyquin, its heavier chalcogen analogues, and the corresponding 6-PhS, 6-PhSe, and 6-PhTe derivatives were assayed for both their chain-breaking antioxidative capacity and their ability to catalyze reduction of hydrogen peroxide in the presence of a stoichiometric amount of a thiol reducing agent (thiol peroxidase activity). Ethoxyquin itself turned out to be the best inhibitor of azo-initiated peroxidation of linoleic acid in a water/chlorobenzene two-phase system. In the absence of N-acetylcysteine as a coantioxidant in the aqueous phase, it inhibited peroxidation as efficiently as alpha-tocopherol but with a more than 2-fold longer inhibition time. In the presence of 0.25 mM coantioxidant in the aqueous phase, the inhibition time was further increased by almost a factor of 2. This is probably due to thiol-mediated regeneration of the active antioxidant across the lipid-aqueous interphase. The ethyltelluro analogue 1d of ethoxyquin was a similarly efficient quencher of peroxyl radicals compared to the parent in the two-phase system, but less regenerable. Ethoxyquin was found to inhibit azo-initiated oxidation of styrene in the homogeneous phase (chlorobenzene) almost as efficiently (kinh = (2.0 +/- 0.2) x 106 M-1 s-1) as alpha-tocopherol with a stoichiometric factor n = 2.2 +/- 0.1. At the end of the inhibition period, autoxidation was additionally retarded, probably by ethoxyquin nitroxide formed during the course of peroxidation. The N-H bond dissociation enthalpy of ethoxyquin (81.3 +/- 0.3 kcal/mol) was determined by a radical equilibration method using 2,6-dimethoxyphenol and 2,6-di-tert-butyl-4-methylphenol as equilibration partners. Among the investigated compounds, only the tellurium analogues 1d and, less efficiently, 1g had a capacity to catalyze reduction of hydrogen peroxide in the presence of thiophenol. Therefore, analogue 1d is the only antioxidant which is multifunctional (chain-breaking and preventive) in character and which can act in a truly catalytic fashion to decompose both peroxyl radicals and organic hydroperoxides in the presence of suitable thiol reducing agents.

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Section: Introductionmentioning

confidence: 99%

Antioxidant Profile of Ethoxyquin and Some of Its S, Se, and Te Analogues

et al. 2007

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Synthesis and biological activity of fibrate-based acyl- and alkyl-phenoxyacetic methyl esters and 1,2-dihydroquinolines

et al. 2020

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Ethoxyquin: An Antioxidant Used in Animal Feed

Błaszczyk

Augustyniak

Skolimowski

2013

International Journal of Food Science

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101

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Ethoxyquin (EQ, 6-ethoxy-1,2-dihydro-2,2,4-trimethylquinoline) is widely used in animal feed in order to protect it against lipid peroxidation. EQ cannot be used in any food for human consumption (except spices, e.g., chili), but it can pass from feed to farmed fish, poultry, and eggs, so human beings can be exposed to this antioxidant. The manufacturer Monsanto Company (USA) performed a series of tests on ethoxyquin which showed its safety. Nevertheless, some harmful effects in animals and people occupationally exposed to it were observed in 1980's which resulted in the new studies undertaken to reevaluate its toxicity. Here, we present the characteristics of the compound and results of the research, concerning, for example, products of its metabolism and oxidation or searching for new antioxidants on the EQ backbone.

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Preparation of ethoxyquin salts and their genotoxic and antioxidant effects on human lymphocytes

Cited by 4 publications

References 10 publications

Antioxidant Profile of Ethoxyquin and Some of Its S, Se, and Te Analogues

Antioxidant Profile of Ethoxyquin and Some of Its S, Se, and Te Analogues

Synthesis and biological activity of fibrate-based acyl- and alkyl-phenoxyacetic methyl esters and 1,2-dihydroquinolines

Ethoxyquin: An Antioxidant Used in Animal Feed

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