Insights into the Endocrine Disrupting Activity of Emerging Non-Phthalate Alternate Plasticizers against Thyroid Hormone Receptor: A Structural Perspective

Unlocking the Reverse Targeting Mechanisms of Cannabidiol: Unveiling New Therapeutic Avenues

Cannabidiol (CBD) and Δ9-tetrahydrocannabinol (THC), the main components of Cannabis sativa plants, have attracted a significant amount of attention due to their biological activities. This study identified GPR18 as the target of partial agonist CBD activating the p42/p44 MAPK pathway leading to migration of endometrial epithelial cells. Induced fit docking (IFD) showed that the affinity of THC for GPR18 is higher than that of CBD, and molecular dynamics (MD) simulations showed that CBD-GPR18 complexes at 130/200 ns might have stable conformations, potentially activating GPR18 by changing the distances of key residues in its active pocket. In contrast, THC maintains "metastable" conformations, generating a "shrinking space" leading to full agonism of THC by adding mechanical constraints in GPR18's active pocket. Steered molecular dynamics (SMD) revealed GPR18's active pocket was influenced more by CBD's partial agonism compared with THC. This combined IFD-MD-SMD method may be used to explain the mechanism of activation of partial or full agonists of GPR18.

Phthalates and other organic chemicals in agricultural soils after use of different types of conventional and biodegradable plastics

Various plastic materials are used in contact with agricultural soil, like mulching films, crop covers, weed controlling fabrics and nets. Polyethylene (PE) mulches have already been recognized as a significant source of plastic in soil and they have been shown to contain additives like phthalates, known as endocrine disruptors. However, other agricultural plastics are less studied, and little is known on the substances potentially released from them endangering biodiversity and the human health. This research aims to assess whether different agricultural plastics release additives into soil and to compare the release among various materials. We collected soil samples from 38 agricultural fields where conventional mulching films (PE), weed controlling fabrics (PP), biodegradable mulches based on polybutylene adipate terephthalate (PBAT), frost covers (PP), and oxo-degradable films (at least OXO-PE) were used. We analyzed the soils for phthalates and acetyl tributyl citrate (ATBC), used as plastic additives, and for polycyclic aromatic hydrocarbons (PAH) and dodecane that have high affinity for plastics. In comparison to the control soils, dibutylphthalate (DBP) and ATBC concentrations were significantly higher in soils mulched with PE and, partly, with biodegradable films. DBP concentration found in soil samples ranged between below the limit of quantification at a control site (1.5 μg kg-1) to 135 μg kg-1 at a site mulched with OXO-PE. The highest ATBC concentration, 22 ± 6 μg kg-1, was registered in a site mulched with PE, showing a statistically significant difference not only in comparison to the controls but also when compared to sites mulched with OXO-PE (p = 0.029) and PBAT (p < 0.009). On the contrary, the use of agricultural plastics did not influence the concentration of PAHs and dodecane. Our results indicate that agricultural plastics are a source of some organic chemicals to agricultural soils, including phthalates that are known for posing threat to soil ecosystem and human health.

In silico analysis of endocrine-disrupting potential of triclosan, bisphenol A, and their analogs and derivatives

Owning to the increasing body of evidence about the ubiquitous exposure to endocrine disruptors (EDCs), particularly bisphenol A (BPA), and associated health effects, BPA has been gradually substituted with insufficiently tested structural analogs. The unmanaged excessive use of antimicrobial agents such as triclosan (TCS) during the COVID-19 outbreak has also raised concerns about its possible interferences with hormonal functions. The similarity of BPA and estradiol, as well as TCS and non-steroidal estrogens, imply that endocrine-disrupting properties of their analogs could be predicted based on the chemical structure. Hence, this study aimed to evaluate the endocrine-disrupting potential of BPA substitutes as well as TCS derivatives and degradation/biotransformation metabolites, in comparison to BPA and TCS based on their molecular properties, computational predictions of pharmacokinetics and binding affinities to nuclear receptors. Based on the obtained results several under-researched BPA analogs exhibited higher binding affinities for nuclear receptors than BPA. Notable analogs included compounds detected in receipts (DD-70, BTUM-70, TGSA, and BisOPP-A), along with a flame retardant, BDP. The possible health hazards linked to exposure to TCS and its mono-hydroxylated metabolites were also found. Further research is needed in order to elucidate the health impacts of these compounds and promote better regulation practices.

Calculating toxic pressure for mixtures of endocrine disruptors

Incidence of autoimmune disorders, birth defects, and neurological diseases rose over the past 50 years due to increasing variety and quantity of pollutants. To date, there appear few methods capable to evaluate and predict mixture effects by endocrine disruptors (EDs). For the first time, we have developed calculus to determine mixture effects by all kinds of EDs. Our method uses the golden ratio ϕ and draws from bifurcation and chaos theory. Using also the concept of molecular mimicry, we developed the equation: e f f e c t = 100 % 1 + e 5 · ∑ K i C i - n i ϕ 3 . We successfully tested the equation using a range of cohort studies and biomarkers, and for different pollutants like heavy metals, thyroid hormone mimickants, chromate/chlorate, etc. The equation is simple enough to use with only minor prior knowledge and understanding of basic algebra. The method is universal and calculation is data 'light', requiring only pollutant concentrations [C], potencies K and an integer n for endocrinal involvement. This study offers a comprehensive framework to assess the health effects of pollutant exposure across diverse populations, envisioning far-reaching impact, and presenting practical examples and insights.

First Insight into Fetal Exposure to Legacy and Emerging Plasticizers Revealed by Infant Hair and Meconium: Occurrence, Biotransformation, and Accumulation

Epidemiological studies have demonstrated the embryonic and developmental toxicity of plasticizers. Thus, understanding the in utero biotransformation and accumulation of plasticizers is essential to assessing their fate and potential toxicity in early life. In the present study, 311 infant hair samples and 271 paired meconium samples were collected at birth in Guangzhou, China, to characterize fetal exposure to legacy and emerging plasticizers and their metabolites. Results showed that most of the target plasticizers were detected in infant hair, with medians of 9.30, 27.6, and 0.145 ng/g for phthalate esters (PAEs), organic phosphate ester (OPEs), and alternative plasticizers (APs), and 1.44, 0.313, and 0.066 ng/g for the metabolites of PAEs, OPEs, and APs, respectively. Positive correlations between plasticizers and their corresponding primary metabolites, as well as correlations among the oxidative metabolites of bis(2-ethylhexyl) phthalate (DEHP) and 1,2-cyclohexane dicarboxylic acid diisononyl ester (DINCH), were observed, indicating that infant hair retained the major phase-I metabolism of the target plasticizers. While no positive correlations were found in parent compounds or their primary metabolites between paired infant hair and meconium, significant positive correlations were observed among secondary oxidative metabolites of DEHP and DINCH in hair and meconium, suggesting that the primary metabolites in meconium come from hydrolysis of plasticizers in the fetus but most of the oxidative metabolites come from maternal-fetal transmission. The parent compound/metabolite ratios in infant hair showed a decreasing trend across pregnancy, suggesting in utero accumulation and deposition of plasticizers. To the best of our knowledge, this study is the first to report in utero exposure to both parent compounds and metabolites of plasticizers by using paired infant hair and meconium as noninvasive biomonitoring matrices and provides novel insights into the fetal biotransformation and accumulation of plasticizers across pregnancy.

Effects of two alternative plasticizers on the growth hormone-related endocrine system, neurodevelopment, and oxidative stress of zebrafish larvae

In response to the restriction of phthalate plasticizers, acetyl tributyl citrate (ATBC) and acetyl triethyl citrate (ATEC) have been used in medical devices and food packaging. In the present study, the effects of ATBC and ATEC on the development, behavior, growth hormone (GH)-related endocrine system, neurotransmitters, and oxidative stress of zebrafish embryo or larvae were investigated. After exposure of zebrafish to ATBC and ATEC (0, 0.03, 0.3, 3, 30, and 300 μg/L) for 96 h, developmental toxicity, behavioral changes under light/dark condition, changes in hormones and genes involved in GH/insulin-like growth factors (IGFs) axis, changes in hormone, enzyme, and genes related to neurodevelopment, antioxidant enzymes activities were determined. Larvae exposed to 30 or 300 μg/L ATBC showed significant reductions in body length and moving distance and speed, whereas no significant effects on development and locomotor behavior were observed in larvae exposed to ATEC. The contents of GH and IGF-I were significantly reduced in larvae exposed to 3, 30, and 300 μg/L ATBC. Hormonal changes in fish exposed to ATBC are well supported by regulation of genes related to GH (gh1) and the activity of IGF-I (igf1). In fish exposed to ATBC, reduced acetylcholinesterase activity and down-regulation of genes related to the central nervous system development (ache, gap43, mbpa, and syn21) were observed. ATBC increased the production of reactive oxygen species and the levels of superoxide dismutase, catalase, and glutathione peroxidase. Notably, pre-treatment with the classic antioxidant N-acetylcysteine alleviated ATBC-induced GH-related endocrine disruption and neurotoxicity. Our observations showed that exposure to low levels of ATBC could disturb the regulatory systems of GH/IGFs axis and neurobehavior, ultimately leading to developmental inhibition and hypoactivity, and that increased oxidative stress plays a major role in these toxicities.

Co-occurrence of phthalate and non-phthalate plasticizers in dust and hand wipes: A comparison of levels across various sources

E-waste dismantlers' occupational exposure to plasticizers, particularly non-phthalate (NPAE) plasticizers, is poorly understood. This study monitored 11 phthalates (PAEs) and 16 NPAEs in dust and hand wipe samples from Central China e-waste workplace and ordinary homes. Concentrations of plasticizers in dust from e-waste dismantling workshops (median: 217 μg/g) were significantly lower than that from ordinary homes (462 μg/g; p < 0.01), however, the trend was similar but not significant in hand wipes from these two scenarios (50.2 vs. 72.3 μg/m2; p = 0.139). PAEs were still the dominant plasticizers, which is, on average, 5.46 and 3.58-fold higher than NPAEs. In all samples, di-(2ethylhexyl) phthalate (65.4%) and tri-octyl trimellitate (44.9%) were the most common PAE and NPAE plasticizers. Increasing dust concentrations of di-iso-nonyl ester 1,2-cyclohexane dicarboxylic acid, citrates and sebacates were significantly associated with their levels in worker's hand wipe, by contrast, this trend was not found in general population. Dust ingestion was the main channel, followed by hand-to-mouth contact, all participants' daily plasticizer intakes (median: 154 ng/kg bw/day) are within safety limits. Our work highlights knowledge gaps about co-exposure to PAEs and NPAEs by multiple pathways in occupational e-waste workers, which could provide baseline data in the future.

An Analysis of the Structural Relationship between Thyroid Hormone-Signaling Disruption and Polybrominated Diphenyl Ethers: Potential Implications for Male Infertility

Polybrominated diphenyl ethers (PBDEs) are a common class of anthropogenic organobromine chemicals with fire-retardant properties and are extensively used in consumer products, such as electrical and electronic equipment, furniture, textiles, and foams. Due to their extensive use, PBDEs have wide eco-chemical dissemination and tend to bioaccumulate in wildlife and humans with many potential adverse health effects in humans, such as neurodevelopmental deficits, cancer, thyroid hormone disruption, dysfunction of reproductive system, and infertility. Many PBDEs have been listed as chemicals of international concern under the Stockholm Convention on Persistent Organic Pollutants. In this study, the aim was to investigate the structural interactions of PBDEs against thyroid hormone receptor (TRα) with potential implications in reproductive function. Structural binding of four PBDEs, i.e., BDE-28, BDE-100, BDE-153 and BDE-154 was investigated against the ligand binding pocket of TRα using Schrodinger's induced fit docking, followed by molecular interaction analysis and the binding energy estimation. The results indicated the stable and tight binding of all four PDBE ligands and similarity in the binding interaction pattern to that of TRα native ligand, triiodothyronine (T3). The estimated binding energy value for BDE-153 was the highest among four PBDEs and was more than that of T3. This was followed by BDE-154, which is approximately the same as that of TRα native ligand, T3. Furthermore, the value estimated for BDE-28 was the lowest; however, the binding energy value for BDE-100 was more than BDE-28 and close to that of TRα native ligand, T3. In conclusion, the results of our study suggested the thyroid signaling disruption potential of indicated ligands according to their binding energy order, which can possibly lead to disruption of reproductive function and infertility.

Application of In Vitro Models for Studying the Mechanisms Underlying the Obesogenic Action of Endocrine-Disrupting Chemicals (EDCs) as Food Contaminants-A Review

Obesogenic endocrine-disrupting chemicals (EDCs) belong to the group of environmental contaminants, which can adversely affect human health. A growing body of evidence supports that chronic exposure to EDCs can contribute to a rapid increase in obesity among adults and children, especially in wealthy industrialized countries with a high production of widely used industrial chemicals such as plasticizers (bisphenols and phthalates), parabens, flame retardants, and pesticides. The main source of human exposure to obesogenic EDCs is through diet, particularly with the consumption of contaminated food such as meat, fish, fruit, vegetables, milk, and dairy products. EDCs can promote obesity by stimulating adipo- and lipogenesis of target cells such as adipocytes and hepatocytes, disrupting glucose metabolism and insulin secretion, and impacting hormonal appetite/satiety regulation. In vitro models still play an essential role in investigating potential environmental obesogens. The review aimed to provide information on currently available two-dimensional (2D) in vitro animal and human cell models applied for studying the mechanisms of obesogenic action of various industrial chemicals such as food contaminants. The advantages and limitations of in vitro models representing the crucial endocrine tissue (adipose tissue) and organs (liver and pancreas) involved in the etiology of obesity and metabolic diseases, which are applied to evaluate the effects of obesogenic EDCs and their disruption activity, were thoroughly and critically discussed.

Androgen receptor signaling and pyrethroids: Potential male infertility consequences

Infertility is a global health concern inflicting a considerable burden on the global economy and a severe socio-psychological impact. Approximately 15% of couples suffer from infertility globally, with a male factor contribution of approximately 50%. However, male infertility remains largely unexplored, as the burden of infertility is mostly assigned to female people. Endocrine-disrupting chemicals (EDCs) have been proposed as one of the factors causing male infertility. Pyrethroids represent an important class of EDCs, and numerous studies have associated pyrethroid exposure with impaired male reproductive function and development. Therefore, the present study investigated the potentially toxic effects of two common pyrethroids, cypermethrin and deltamethrin, on androgen receptor (AR) signaling. The structural binding characterization of cypermethrin and deltamethrin against the AR ligand-binding pocket was performed using Schrodinger's induced fit docking (IFD) approach. Various parameters were estimated, such as binding interactions, binding energy, docking score, and IFD score. Furthermore, the AR native ligand, testosterone, was subjected to similar experiments against the AR ligand-binding pocket. The results revealed commonality in the amino acid-binding interactions and overlap in other structural parameters between the AR native ligand, testosterone, and the ligands, cypermethrin and deltamethrin. The estimated binding energy values of cypermethrin and deltamethrin were very high and close to those calculated for AR native ligand, testosterone. Taken together, the results of this study suggested potential disruption of AR signaling by cypermethrin and deltamethrin, which may result in androgen dysfunction and subsequent male infertility.

Thyroid hormone disruption by bis-(2-ethylhexyl) phthalate (DEHP) and bis-(2-ethylhexyl) adipate (DEHA) in Japanese medaka Oryzias latipes

Pollution of water bodies with plasticizers is a serious environmental problem worldwide. In this study, we investigated the effects of plasticizers bis-(2-ethylhexyl) phthalate (DEHP) and bis-(2-ethylhexyl) adipate (DEHA) in Japanese medaka (Oryzias latipes). DEHP significantly increased the expression of all the genes tested: thyroid stimulating hormone beta subunit (tshβ-like), tshβ, deiodinase 1 (dio1), deiodinase 2 (dio2), and thyroid hormone receptor alpha (trα) and beta (trβ). However, DEHA only significantly increased tshβ at 7.4 µg/L but significantly decreased dio2 expression at 25.8, 111.1, and 412.6 4 µg/L, while other genes were not significantly affected. Both chemicals reduced eye size and total body length, but did not affect embryo development, hatching time and rate, and swimming performance. DEHA alone affected swim bladder inflation and not DEHP. This is the first report that not only DEHP but also DEHA disrupt thyroid hormone activity in fish. DEHP contamination (13.2 μg/L) was detected in tap water from Kobe, Japan; thus, tap water itself may disrupt thyroid hormone activity in Japanese medaka. Importantly, the effective concentration of DEHP for thyroid hormone-related gene expression and growth was close to or lower than DEHP concentrations reported in surface water elsewhere, indicating that DEHP contamination is a serious aquatic pollution.