Isomer-Specific Degradation and Endocrine Disrupting Activity of Nonylphenols

Abstract

Degradation of technical nonylphenol by Sphingobium xenophagum Bayram led to a significant shift in the isomers composition of the mixture. By means of gas chromatography-mass spectrometry, we could observe a strong correlation between transformation of individual isomers and their alpha-substitution pattern, as expressed by their assignment to one of six mass spectrometric groups. As a rule, isomers with less bulkiness at the alpha-carbon and those with an optimally sized main alkyl chain (4-6 carbon atoms) were degraded more efficiently. By mass spectrometric analysis, we identified the two most recalcitrant main isomers of the technical mixture (Group 4) as 4-(1,2-dimethyl-1-propylbutyl)phenols (NP193a and NP193b), which are diastereomers with a bulky alpha-CH3, alpha-CH(CH3)C2H5 substitution. Our experiments with strain Bayram show that the selective enrichment of isomers with bulky alpha-substitutions observed in nonylphenol fingerprints of natural systems can be caused by microbial ipso-hydroxylation. Based on the yeast estrogen assay (YES), we established an estrogenicity ranking with a variety of single isomers and compared it to rankings obtained with different reporter cell systems. Structure-activity relationships derived from these data suggest that Group 4 isomers have a high estrogenic potency. This indicates a substantial risk that enrichment of highly estrogenic isomers during microbial degradation by ipso-substitution will increase the specific estrogenicity of aging material.

Intracellular proteome expression during 4-n-nonylphenol biodegradation by the filamentous fungus Metarhizium robertsii

“…Proteomic studies of filamentous fungi have only recently begun to appear in the literature, despite the prevalence of these organisms in the fields of biotechnology, industry and environmental protection and their importance as both human and plant pathogens (Kim et al 2007;Doyle 2011;Bregar et al, 2012;Salvachúa et al 2013;Kroll et al 2014). Although the fungal biodegradation pathways of 4-NP have been proposed for several fungal organisms (Junghanns et al 2005;Gabriel et al 2008;Girlanda et al 2009;Różalska et al 2010;Krupiński et al 2013), little is known about the proteomic background of these processes. In the current work, the 4-n-NP biodegradation pathway in the filamentous fungus, Metarhizium robertsii, which leads to the complete removal of the xenobiotic through consecutive oxidations of the alkyl chain followed by aromatic ring oxidation and the initial proteome background of 4-n-NP removal, was described.…”

Toxic Substances in Articles

“…Wastewater treatment decreases the concentration of NPEs but increases the concentration of the toxic metabolites of NPEs. 67 Use. Studies have found that textiles manufactured in factories that use NPEs frequently contain residual NPEs in the final product.…”

Quantification of the Influence of Extracellular Laccase and Intracellular Reactions on the Isomer-Specific Biotransformation of the Xenoestrogen Technical Nonylphenol by the Aquatic HyphomyceteClavariopsis aquatica

“…Nonylphenols are known to disrupt normal endocrine functions in vertebrates (57). Certain isomers contained in t-NP have been reported to possess a considerably higher estrogenic activity than the t-NP mixture (15). Due to increasing concerns with respect to their largely unknown environmental fate and potentially adverse environmental and human health effects, nonylphenols have been listed as priority hazardous substances in the EU water framework directive.…”

“…Bacterial degradation pathways have only been documented in the genera Sphingomonas and Sphingobium. Bacterial mineralization of the aromatic moiety of t-NP isomers to CO 2 and H 2 O is initiated via ring hydroxylation at the ipso (C-4) position of the phenolic ring, and nonanols are produced from the nonyl chains (10,11,15,16). Bacteria have been shown to utilize branched-chain nonylphenols as growth substrates (11,12,17,43).…”

“…Recent literature data indicate that certain t-NP isomers with an estrogenic potency higher than those of the original t-NP mixture can be enriched in remaining t-NP. This results from the selective removal of individual isomers upon bacterial ipso-substitution degradation mechanisms (15). However, the effects of fungal biotransformation reactions on the isomeric profile of t-NP have not yet been quantified.…”