Response to Comments on “Endocrine Disrupting Nonylphenols Are Ubiquitous in Food”

Guenther, Klaus; Heinke, Volkmar; Thiele, Bjoern; Kleist, E.; Prast, Hartmut; Raecker, Torsten

doi:10.1021/es0300057

Cited by 14 publications

(5 citation statements)

References 7 publications

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“…Nonylphenols are highly toxic to aquatic organisms (25,32,35) and are able to mimic estrogens in fishes, mammals, and other animals (33,35,41). The estrogenic activity of the individual isomers varies widely (16,23), and therefore the isomeric composition of nonylphenol mixtures needs to be taken into account for investigations about the environmental fate and the toxic effects of nonylphenol compounds (17).…”

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confidence: 99%

Elucidation of theipso-Substitution Mechanism for Side-Chain Cleavage of α-Quaternary 4-Nonylphenols and 4-t-Butoxyphenol inSphingobium xenophagumBayram

Gabriel

Cyris

Jonkers

et al. 2007

Appl Environ Microbiol

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Recently we showed that degradation of several nonylphenol isomers with ␣-quaternary carbon atoms is initiated by ipso-hydroxylation in Sphingobium xenophagum Bayram (F. L. P. Gabriel, A. Heidlberger, D. Rentsch, W. Giger, K. Guenther, and H.-P. E. Kohler, J. Biol. Chem. 280: [15526][15527][15528][15529][15530][15531][15532][15533] 2005). Here, we demonstrate with 18 O-labeling experiments that the ipso-hydroxy group was derived from molecular oxygen and that, in the major pathway for cleavage of the alkyl moiety, the resulting nonanol metabolite contained an oxygen atom originating from water and not from the ipso-hydroxy group, as was previously assumed. Our results clearly show that the alkyl cation derived from the ␣-quaternary nonylphenol 4-(1-ethyl-1,4-dimethylpentyl)-phenol through ipso-hydroxylation and subsequent dissociation of the 4-alkyl-4-hydroxy-cyclohexadienone intermediate preferentially combines with a molecule of water to yield the corresponding alcohol and hydroquinone. However, the metabolism of certain ␣,␣-dimethyl-substituted nonylphenols appears to also involve a reaction of the cation with the ipso-hydroxy group to form the corresponding 4-alkoxyphenols. Growth, oxygen uptake, and 18 O-labeling experiments clearly indicate that strain Bayram metabolized 4-tbutoxyphenol by ipso-hydroxylation to a hemiketal followed by spontaneous dissociation to the corresponding alcohol and p-quinone. Hydroquinone effected high oxygen uptake in assays with induced resting cells as well as in assays with cell extracts. This further corroborates the role of hydroquinone as the ring cleavage intermediate during degradation of 4-nonylphenols and 4-alkoxyphenols.Technical nonylphenol is a complex mixture of more than 100 isomers which differ in the structure and the position of the alkyl moiety attached to the phenol ring (20). More than 90% of the mixture consists of para-substituted nonylphenols (36, 40). The technical product serves mainly in the manufacture of nonylphenol polyethoxylates, a class of nonionic surfactants that have a wide range of industrial applications and are used in large amounts worldwide (36). Because such surfactants are designed for usage in aqueous solutions, they are discharged mainly into wastewaters and thereby enter sewage treatment plants, where they are rapidly degraded to more-recalcitrant metabolites, such as short-chain nonylphenol ethoxylates, carboxylic acid derivatives, and nonylphenols (1, 2, 4, 38). Nonylphenols are highly toxic to aquatic organisms (25,32,35) and are able to mimic estrogens in fishes, mammals, and other animals (33,35,41). The estrogenic activity of the individual isomers varies widely (16, 23), and therefore the isomeric composition of nonylphenol mixtures needs to be taken into account for investigations about the environmental fate and the toxic effects of nonylphenol compounds (17).Recently isolated microorganisms (12,13,37) are able to grow with ␣-quaternary nonylphenols as the sole sources of carbon and energy. These bacteria degrade nonylphenol...

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confidence: 99%

Elucidation of theipso-Substitution Mechanism for Side-Chain Cleavage of α-Quaternary 4-Nonylphenols and 4-t-Butoxyphenol inSphingobium xenophagumBayram

Gabriel

Cyris

Jonkers

et al. 2007

Appl Environ Microbiol

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“…Surfactants are chemicals that help insecticides distribute, moisten, and penetrate more easily. It has been discovered that certain surfactants, such as alkylphenol ethoxylates (APEs) and nonylphenol ethoxylates (NPEs), are harmful to aquatic life and have endocrine-disrupting effects [ [91] , [92] , [93] , [94] ]. In an analogous way, pesticide shelf life and stability are improved by stabilizers and preservatives.…”

Section: Resultsmentioning

confidence: 99%

Pesticides impacts on human health and the environment with their mechanisms of action and possible countermeasures

Ahmad,

Alsayegh

et al. 2024

Heliyon

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“…In ersten Untersuchungen wurden Unterschiede von mehreren Größenordnungen ermittelt (Abb. 2) (Günther et al, 2003).…”

Section: Isomerenspezifische Aspekteunclassified

Estrogen-aktive Metabolite der Alkylphenolethoxylate in Lebensmitteln: Eine ungelöste und komplexe Problematik

Günther

2006

J. Verbr. Lebensm.

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Response to Comments on “Endocrine Disrupting Nonylphenols Are Ubiquitous in Food”

Cited by 14 publications

References 7 publications

Elucidation of theipso-Substitution Mechanism for Side-Chain Cleavage of α-Quaternary 4-Nonylphenols and 4-t-Butoxyphenol inSphingobium xenophagumBayram

Elucidation of theipso-Substitution Mechanism for Side-Chain Cleavage of α-Quaternary 4-Nonylphenols and 4-t-Butoxyphenol inSphingobium xenophagumBayram

Pesticides impacts on human health and the environment with their mechanisms of action and possible countermeasures

Estrogen-aktive Metabolite der Alkylphenolethoxylate in Lebensmitteln: Eine ungelöste und komplexe Problematik

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