Chronic toxicity and endocrine-disrupting effects of 4-tert-octylphenol and 4-tert-butylphenol in Daphnia magna.

Authors

Feyza Icoglu Aksakal, Özkan Aksakal

Published in

Comparative biochemistry and physiology. Toxicology & pharmacology : CBP. Volume 308. Pages 110609. Jul 06, 2026. Epub Jul 06, 2026.

Abstract

Alkylphenols such as 4-tert-octylphenol (4-tert-OP) and 4-tert-butylphenol (4-tert-BP) are recognized endocrine disruptors frequently detected in aquatic environments; however, their long-term effects on freshwater invertebrates remain insufficiently characterized. This study investigated the chronic toxicity and endocrine-disrupting effects of 4-tert-OP and 4-tert-BP on Daphnia magna using a comprehensive suite of endpoints, including life-history traits, physiological responses, oxidative stress markers, behavioral assessments, and gene expression analyses. Both compounds induced significant, concentration-dependent adverse effects, including reduced survival, growth inhibition, delayed reproduction, decreased offspring production, and reduced molting frequency. Biochemical assays revealed alterations in antioxidant enzyme activities, specifically changes in superoxide dismutase (SOD) and catalase (CAT), as well as elevated malondialdehyde (MDA) levels, indicative of oxidative stress and lipid peroxidation. Acetylcholinesterase (AChE) activity decreased, and swimming performance declined, indicating neurotoxic effects. At the molecular level, both alkylphenols downregulated genes associated with molting and hormonal regulation, including chitinase, cuticle protein, and key components of the ecdysteroid signaling pathway (ecra, ecrb, hr3, e75, and rxr). Additionally, the vitellogenin genes (vtg1 and vtg2), which are essential for reproduction, were suppressed. Collectively, these results demonstrate that 4-tert-OP and 4-tert-BP disrupt multiple biological targets in D. magna, with oxidative stress, neurotoxicity, and hormonal interference contributing to impaired growth and reproduction. These findings underscore the ecological risks posed by alkylphenol contamination and highlight the necessity of integrating multiple lines of evidence in environmental risk assessments.

PMID:
42407138
Bibliographic data and abstract were imported from PubMed on 07 Jul 2026.

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