Accumulation of endocrine disrupting chemicals in the liver of Diplodus sargus sargus in Torre Guaceto Natural Reserve

Impact of 2,4-di-tert-butylphenol on pancreatic lipase activity in emulsions: Multispectral, molecular docking, and in vitro digestion analysis

2,4-di-tert-butylphenol (2,4-DTBP) is an additive used in food packaging. The inhibitory effects of 2,4-DTBP on pancreatic lipase (PL) were investigated in this study. Kinetic analysis indicated that 2,4-DTBP competitively and reversibly inhibited PL activity. At 4.85 mM, PL activity decreased by 35.5 ± 1.6 %. 2,4-DTBP quenched the fluorescence of PL by hydrogen bonding and van der Waals forces. Circular dichroism spectroscopy showed that 2,4-DTBP induced changes in the secondary structure of PL. Molecular docking revealed that 2,4-DTBP interacted with Phe77, Leu153, and Ser152 residues of PL, which account for suppressing lipid hydrolysis. An in vitro digestion study showed that 2,4-DTBP inhibited the digestion of lipid in oil-in-water emulsions. This study improved our understanding of the effects of 2,4-DTBP on digestive enzyme. It also underscored the need for better monitoring and control of the leaching of this additive from packaging materials into foods.

Long-term exposure to 2,4-di-tert-butylphenol impairs zebrafish fecundity and affects offspring development

As a widely used antioxidant, 2,4-di-tert-butylphenol (2,4-DTBP) has been frequently detected in the environment and biota. Although a few studies reported its hormone-like activity in vitro, the endocrine disrupting potential of 2,4-DTBP and its effect on reproduction are not yet elucidated. In this study, adult zebrafish were exposed to 5 and 50 nM 2,4-DTBP for 60 days. Reduction in cumulative egg production was observed after 45 days of exposure. Gonadal maturation was also delayed in both female and male zebrafish following 2,4-DTBP exposure. The impaired fecundity was attributed to an imbalance of 17β-estradiol/testosterone ratio (E2/T) and altered transcripts involved in the hypothalamic-pituitary-gonadal (HPG) axis. Upon exposure, aromatase (CYP19) and E2 levels were significantly decreased in females, but were increased in males. Additionally, molecular docking revealed potential binding of 2,4-DTBP to estrogen receptors and CYP19, highlighting molecular initiating events that may interfere with steroid hormone synthesis. We also showed that 2,4-DTBP can be transferred to offspring, affecting their development and compromising immunity. The expression of triiodothyronine (T3) and hatching-related genes (esr2α, esr2β, and zhe2) were altered, suggesting that parental exposure to 2,4-DTBP resulted in intergenerational toxicity in F1 larvae. Taken together, these findings provide novel insight into the reproductive toxicity of 2,4-DTBP, contributing to its ecological risk assessment.

Comprehensive analysis of water and sediment from holy water body 'Pokhri' reveals presence of biomolecules that may educe skin, gastroenterological and neurological dysfunction

'Pokhri mai' refers to the natural pond amidst the hilly forest slopes of the Buxa tiger reserve (BTR) nearby Jayanti considered to be sacred by the local ethnic groups serving as the prime source of water for wild animals and occasionally by neighbouring inhabitants. However, the water body is designated to be noxious by a group of native people with no scientific validation. This paper focuses to explore its toxicity status and allied environmental concerns through Pokhri water and sediment sample analysis through physicochemical assessment, in vitro antioxidant assay, microbiological investigation followed by AAS, GC-MS and in silico study. pH of soil and water samples were found to be quite high (>6.8) with organic matter, carbon and available nitrogen content being 1.5308 ± 0.28 %, 0.89 ± 0.17 % and 0.072 ± 0.34 % respectively. Profuse microbial growths were observed in both sediment and water samples with consortia obtained exhibiting tolerance against a range of antifungals and antibiotics. Inhibition zone was absent for sediment consortium whereas consortium of water samples portrayed susceptibility against various heavy metals viz. Cu2+, Pb2+, Zn2+, Fe3+ and Al3+ salts with corresponding AAS quantified values of sediment samples being 133, 223.3, 86.8, 1449 and 481.5 ppm. A summative of 18 metabolites were identified by GC-MS in Pokhri lake sediment among which 13 (occupying 96.35 % peak area) were investigated to be potentially toxic with 2,4-Di-tert-butylphenol (53.38 %) as the major compound. Biomolecular characterization, ADMET test and molecular docking study with dermal, gastrointestinal and neural peptides exhibiting high binding affinity scores (ranging between -2.6 to -8.3 kcal/mol) further affirmed the toxicity attributes of the GC-MS deciphered molecules. The findings clearly justifies the local 'myth' of Pokhri water to be deleterious with prospective dermatotoxic, neurotoxic and being evident of gastrointestinal toxicity emphasizing ecological risk to the environment, wildlife and microflora of the adjoining forests.

A study on the performance, structure, composition, and release behavior changes of polybutylene adipate terephthalic acid (PBAT) film during food contact

Polybutylene adipate terephthalic acid (PBAT) is an emerging biodegradable material in food packaging. However, concerns have been raised regarding the potential hazards it could pose to food safety. In this study, the changes of PBAT films during food contact and the release of small molecules were inestigated by a multiscale approach. On a macro-scale, the surface roughness of the films increased with the reduction in the concentration of food simulants and the increase in contact temperatures, especially after immersion in acidic food environments. On a micro-scale, the crystallinity (Xc) and degradation indexes (DI) of the films increased by 5.7-61.2% and 7.8-48.6%, respectively, which led to a decrease in thermal stability. On a scale approaching the molecular level, 2,4-di-tert-butylphenol (2,4-DTBP) was detected by gas chromatography-mass spectrometry (GC-MS/MS) with the highest migration content, and the release behavior of 2,4-DTBP was further investigated by migration kinetics. In addition, terephthalic acid (TPA), a hydrolysis product of PBAT, was detected in acidic food environments by liquid chromatography-mass spectrometry (LC-MS/MS). The results of this study could provide practical guidance and assistance to promote sustainable development in the field of food packaging.

Effects of the plastic additive 2,4-di-tert-butylphenol on intestinal microbiota of zebrafish

Plastic additives such as the antioxidant 2,4-di-tert-butylphenol (2,4-DTBP) have been widely detected in aquatic environments, over a wide range of concentrations reaching 300 μg/L in surface water, potentially threatening the health of aquatic organisms and ecosystems. However, knowledge of the specific effects of 2,4-DTBP on aquatic vertebrates is still limited. In this study, adult zebrafish were exposed to different concentrations of 2,4-DTBP (0, 0.01, 0.1 and 1.0 mg/L) for 21 days in the laboratory. The amplicon sequencing results indicated that the diversity and composition of the zebrafish gut microbiota were significantly changed by 2,4-DTBP, with a shift in the dominant flora to more pathogenic genera. Exposure to 2,4-DTBP at 0.1 and 1.0 mg/L significantly increased the body weight and length of zebrafish, suggesting a biological stress response. Structural assembly defects were also observed in the intestinal tissues of zebrafish exposed to 2,4-DTBP, including autolysis of intestinal villi, adhesions and epithelial detachment of intestinal villi, as well as inflammation. The transcriptional expression of some genes showed that 2,4-DTBP adversely affected protein digestion and absorption, glucose metabolism and lipid metabolism. These results are consistent with the PICRUSt2 functional prediction analysis of intestinal microbiota of zebrafish exposed to 2,4-DTBP. This study improves our understanding of the effects of 2,4-DTBP on the health of aquatic vertebrates and ecosystems.

Exposure to environmental levels of 2,4-di-tert-butylphenol affects digestive glands and induces inflammation in Asian Clam (Corbicula fluminea)

2,4-Di-tert-butylphenol (2,4-DTBP) is used as an antioxidant added to plastics. Due to its potential toxicity and relatively high concentrations in environments and presence in human tissue, concern has been raised for 2,4-DTBP as a contaminant associated with adverse health outcomes. However, studies on the toxicity of 2,4-DTBP are relatively limited, especially for benthic aquatic organisms. In this study, Asian clams (Corbicula fluminea) were exposed to environmentally relevant concentrations of 2,4-DTBP (0.01-1 μM, corresponding to 2.06-206.32 μg/L) for 21 days. Accumulation of 2,4-DTBP was noted in both gills and digestive glands, with the latter presenting as the primary target tissue. Increased damage rate of digestive tube and cellular DNA damage were observed in the digestive glands of 2,4-DTBP exposed clams. The injury was attributed to the imbalance of the antioxidant system, characterized by elevated oxidative stress and inflammation (upregulation of ROS, MDA, NO, and pro-inflammatory factors). In contrast, upon 2,4-DTBP exposure, antioxidant system in gills was activated, while ROS and NO were not promoted. Moreover, NF-κB and IL-1 were significantly decreased. These results suggested that biochemical mechanisms were activated in gills to maintain homeostasis. Internal exposure in the digestive gland was significantly correlated with the biochemical biomarkers tested, underscoring the potential risk associated with the bioaccumulation of 2,4-DTBP from contaminated environments. These findings provide novel insights into toxicity of 2,4-DTBP in bivalves, contributing valuable knowledge to risk assessment and chemical management.

Adverse effects of plastic leachate and its component 2,4-DTBP on the early development of zebrafish embryos

Plastic waste has become a global environmental problem threatening the health of aquatic organisms especially via leachate. In this study, the test of zebrafish embryo showed adverse effects of leachate from some agricultural mulching films after UV light aging for 60 h. A typical phenolic antioxidant 2,4-di-tert-butylphenol (2,4-DTBP) was detected in the leachate and tested further for the zebrafish embryo biotoxicity. The microplastic leachate (6, 8 g/L, mass concentration measured by weight of plastic) increased the death and malformation rates, and reduced the hatching rate, heart rate, and body length of zebrafish larvae in the 96-hour early development period. Similar adverse effects were also caused by the 2,4-DTBP (0.01, 0.1, 1.0 mg/L, corresponding to 0.049, 0.49, and 4.85 μM) to some degree but could not completely explain the significant influences caused by the plastic leachate. Transcriptome analysis of zebrafish embryos exposed to the 2,4-DTBP for 96 h showed that the protein, fat, and carbohydrate digestion and absorption pathways, pancreatic secretion, PPAR signaling pathway, tryptophan metabolism, and adipocytokine signaling pathway were considerably down-regulated, but the cholesterol metabolism pathway was up-regulated in larval zebrafish. The altered transcriptional expression of mRNA at early development stage (96 h post fertilization) of zebrafish suggested that the 2,4-DTBP caused reduction of digestive capacity and pancreatic secretory function, and adversely affected processes associated with energy metabolism and glycolipid metabolism of larval zebrafish. This study helps us further understanding the effects of plastic leachate on the early development of fishes.

Trophodynamic of endocrine disrupting compounds in the aquatic food webs: Association with hydrophobicity and biota metabolic rate

Increasing concentration of endocrine disrupting compounds (EDCs) are released into the aquatic environment, resulting in irreversible effects on the endocrine and reproductive systems of biota. How the liver enzymes affect metabolic rate of these compounds and thus their structure-related trophic transfer in aquatic food webs remains largely unknown. In this study, the concentrations of seven common EDCs were measured in 15 species of fish, 7 invertebrate species and plankton collected from Liuxi River to Pearl River, South China. The mean ΣEDC concentrations generally were found to increase as follows: plankton (29.59 ng g^-1 dw) < invertebrate species (50.69 ng g^-1 dw) < fish (122.56 ng g^-1 dw), with 4-nonylphenol (4-NP) and bisphenol S (BPS) as the predominant components. Trophic magnification factors (TMFs) values were >1.0 ranged from 1.30 (BPS) to 4.07 (4-NP), indicating trophic magnification potential. Measurement of metabolism and activities of microsomal CYP450 enzymes were performed in the fish liver microsomes of Hypophthalmichthys molitrix ([TL] = 2.27), Cirrhinus mrigala (TL = 3.87) and Odontamblyopus rubicundus (TL = 4.73). TMFs were significantly negatively correlated with the obtained in vitro biotransformation clearance rates (CL _{in vitro}) of EDCs and CYP450 enzymes activities. A multiple linear regression model indicated that biotransformation clearance is a more powerful predictor for TMFs than the hydrophobicity (Kow) to drive changes in the studied aquatic food web trophodynamics.

Environmental concentrations of 2, 4-DTBP cause immunotoxicity in zebrafish (Danio rerio) and may elicit ecological risk to wildlife

Synthetic phenolic antioxidant 2,4-di-tert-butylphenol (2,4-DTBP) has gained growing concerns due to relatively high concentrations in aquatic ecosystems. There are, however, significant knowledge gaps regarding its potential toxicity to aquatic organisms. In this study, zebrafish (Danio rerio) larvae were exposed to 0.01, 0.1, or 1 μM 2,4-DTBP for 6 d. Transcriptomic analysis of larvae revealed that biological processes related to anti-inflammatory function of macrophage M2 lineage were inhibited by 0.01 μM 2,4-DTBP. Decreases of transcripts related to the IL1B-MYD88-NF-κB pathway (i.e., il1b, il1rl1, myd88, irak4, irak1, traf6, ikbkg, nfkbia, nfkb) and protein levels of NF-κB in larvae intestine confirmed anti-inflammatory effects of 2,4-DTBP. Subsequently, larvae exposed to 2,4-DTBP were challenged with E. coli and showed higher survival rate, suggesting sustained activation of inflammation via LPS can be attenuated by 2,4-DTBP. Moreover, histological examination revealed that intestine barrier was compromised and there was an imbalance of intestine macrophage homeostasis. Food intake was also reduced following exposure to 0.1 and 1 μM 2,4-DTBP. In addition, a risk assessment revealed that 2,4-DTBP in surface water pose low to high ecological risks to aquatic organisms. Taken together, exposure to environmentally relevant concentrations of 2,4-DTBP could negatively affect immune response in zebrafish and may elicit ecological risk in fish population.

Neurotoxic effects of synthetic phenolic antioxidants on dopaminergic, serotoninergic, and GABAergic signaling in larval zebrafish (Danio rerio)

Synthetic phenolic antioxidants (SPAs) are an environmental concern because they are widely detected in aquatic ecosystems and can pose potential threats to organisms. Studies have reported developmental deficits and behavioral changes in response to SPAs, indicating possible neurotoxic effects. However, their neuroactive potency as well as their mode of action (MoA) remain unclear. As such, this study evaluated the potential neurotoxicity of three SPAs [butylated hydroxytoluene (BHT), 2,4-di-tert-butylphenol (2,4-DTBP), and 4-tert-octylphenol (4-t-OP)] at three concentrations (0.01, 0.1 and 1 μM) to zebrafish larvae. Both 2,4-DTBP and BHT decreased spontaneous tail coiling (STC) at 28 hpf (hours post fertilization) whereas 4-t-OP increased STC. Locomotor activity, based on the velocity and distance of larvae (144 hpf) travelled, was promoted by 2,4-DTBP while it decreased in larvae with exposure to 4-t-OP and BHT. In the light-dark preference assay, exposure to either 2,4-DTBP or BHT resulted in variability in the visiting frequency to the dark zone, and larvae (144 hpf) spent less time in the dark, suggesting anxiety-like behavior. Conversely, zebrafish exposed to 4-t-OP, especially at 1 μM concentration, were hypoactive and spent more time in dark, suggestive of anxiolytic-like responses. RNA-seq was conducted to discern mechanisms underlying behavioral responses. Transcriptomic analysis revealed that gene networks related to neuroactive ligand-receptor interaction as well as neurotransmitter-related pathways were altered by all three SPAs based on gene set and subnetwork enrichment analysis. Modulation of dopaminergic, serotoninergic, and/or GABAergic signaling at the transcript level was noted for each of the three SPAs, but different expression patterns were observed, indicating SPA- and dose-specific responses of the transcriptome. The present study provides novel insight into potential mechanisms associated with neurotoxicity of SPAs congeners.

Polycyclic aromatic hydrocarbons in breast milk of obese vs normal women: Infant exposure and risk assessment

Biomonitoring of human breast milk is one of the best ways to identify body burdens of contaminants and associated risk estimation. The objectives of the current study were to evaluate milk concentrations of persistent organic pollutants (POPs), mainly polycyclic aromatic hydrocarbons (PAHs), associated exposure estimation, and the role of body mass index (BMI) in their bioaccumulation. A total of 45 breast milk samples were collected from 24 women with BMI > 30 (obese) and 21 women with BMI < 25 (18.5-24.9, normal) from 14 different counties surrounding Lubbock in west Texas/New Mexico (age range: 18-34 years). Samples were analyzed using high resolution gas chromatography coupled with mass spectrometry. A total of 31/45 (69%) of samples tested positive for PAHs. Phenanthrene was the most frequently detected PAH followed by pyrene and fluoranthene. The mean of individual PAH concentration for all samples ranged from 0 to 25.1 ng/g milk fat; the sum of all means of individual PAHs was 146.9 ng/g milk fat. The mean concentration of total PAHs in the BMI > 30 group was 224.8 ng/g milk fat, which was approximately 4 times the mean concentration of total PAHs in the BMI 18.5-24.9 group (57.9 ng/g milk fat). None of the samples from the BMI 18.5-24.9 group contained higher molecular weight (5-6 rings) PAHs, while in the BMI >30 group, a total of 11 PAHs including listed EPA priority pollutants were observed. In this study, benzo(b)fluoranthene was found to contribute the highest percentage of carcinogenic PAHs (32.08%), yet it was not detected in any samples from the BMI 18.5-24.9 group. The estimated total PAHs intakes by infants via obese and normal mothers' milk were 1.26 and 0.32 (μg/kg/day), which are 0.049 and 0.003 (μg/kg/day) B[a]P equivalent, respectively. These findings suggest that breastfed babies from obese mothers are potentially at higher risk of exposure to carcinogenic PAHs.