Cytotoxicity measurement of Bisphenol A (BPA) and its substitutes using human keratinocytes

New Mechanism for the Apoptosis of Human Neuroblastoma Cells by the Interaction between Fluorene-9-Bisphenol and the G Protein-Coupled Estrogen Receptor 1

Fluorene-9-bisphenol (BHPF) is an emerging contaminant. Presently, there is no report on its interaction with G protein-coupled estrogen receptor 1 (GPER). By using an integrated toxicity research scenario that combined theoretical study with experimental methods, BHPF was found to inhibit the GPER-mediated effect via direct receptor binding. Molecular dynamics simulations found that Trp2726.48 and Glu2756.51 be the key amino acids of BHPF binding with GPER. Moreover, the calculation indicated that BHPF was a suspected GPER inhibitor, which neither can activate GPER nor is able to form water channels of GPER. The role of two residues was successfully verified by following gene knockout and site-directed mutagenesis assays. Further in vitro assays showed that BHPF could attenuate the increase in intracellular concentration of free Ca2+ induced by G1-activated GPER. Besides, BHPF showed an enhanced cytotoxicity compared with G15, indicating that BHPF might be a more potent GPER inhibitor than G15. In addition, a statistically significant effect on the mRNA level of GPER was observed for BHPF. In brief, the present study proposes that BHPF be a GPER inhibitor, and its GPER molecular recognition mechanism has been revealed, which is of great significance for the health risk and assessment of BHPF.

Bisphenol A promotes cell death in healthy respiratory system cells through inhibition of cell proliferation and induction of G2/M cell cycle arrest

Bisphenol A (BPA) is a substance that can harm the environment and human health by interfering with the normal functioning of the body's hormonal system. It is commonly found in various plastic-based products such as cosmetics, canned foods, beverage containers, and medical equipment and as well as it can also be absorbed by inhalation. There have been limited studies on the effects of BPA on lung fibroblasts, and it is still unclear how high levels of BPA can impact respiratory system cells, particularly the lungs and trachea. In this research, we aimed to investigate the cell cycle disruption potential of BPA on respiratory system cells by examining healthy trachea and lung cells together for the first time. The findings indicated that BPA exposure can alter the healthy cells' morphology, leading to reduced cellular viability that has been assessed by MTT and SRB assays. BPA treatment was able to activate caspase3 as expected, which could cause apoptosis in treated cells. Although the highest dose of BPA did not increase the apoptotic rate of rat trachea cells, it remarkably caused them to become necrotic (52.12%). In addition to quantifying the induction of apoptosis and necrosis by BPA, cell cycle profiles were also determined using flow cytometry. Thereby, BPA treatment unexpectedly inhibited the cell cycle's progression by causing G2/M cell cycle arrest in both lung and tracheal cells, which hindered cell proliferation. The findings of the study suggested that exposure to BPA could lead to serious respiratory problems, even respiratory tract cancers via alterations in the cell cycle.

Isosorbide, a versatile green chemical: Elucidating its ADME properties for safe use

Isosorbide, an environmentally friendly and renewable substance, finds extensive application in diverse fields, such as a bisphenol A substitute, polymers, functional materials, organic solvents, fuels, and pharmaceuticals. Despite its increasing interest and widespread usage, there remains a notable absence of available reports regarding its absorption, distribution, metabolism, and excretion (ADME) properties. This study endeavors to investigate the ADME characteristics of isosorbide in rats. Isosorbide levels in biological samples were quantified based on the analytical method using gas chromatography-mass spectrometry (GC-MS). Following administration, isosorbide exhibited rapid absorption and elimination, with a bioavailability of 96.1%. The metabolic stability assay indicated that isosorbide remained stable during metabolism. The majority of absorbed isosorbide was promptly excreted, with urinary excretion as the primary route. This study furnishes valuable insights into the ADME of isosorbide, contributing to its safety assessment and fostering its continued application across various domains.

Toxicity overview of endocrine disrupting chemicals interacting in vitro with the oestrogen receptor

The oestrogen receptor (ER) from the nuclear receptor family is involved in different physiological processes, which can be affected by multiple xenobiotics. Some of these compounds, such as bisphenols, pesticides, and phthalates, are widespread as consequence of human activities and are commonly present also in human organism. Xenobiotics able to interact with ER and trigger a hormone-like response, are known as endocrine disruptors. In this review, we aim to summarize the available knowledge on products derived from human industrial activity and other xenobiotics reported to interact with ER. ER-disrupting chemicals behave differently towards oestrogen-dependent cell lines than endogenous oestradiol. In low concentrations, they stimulate proliferation, whereas at higher concentrations, are toxic to cells. In addition, most of the knowledge on the topic is based on individual compound testing, and only a few studies assess xenobiotic combinations, which better resemble real circumstances. Confirmation from in vivo models is lacking also.

The effects of bisphenols on the cardiovascular system ex vivo and in vivo

The human population is regularly exposed to bisphenols. The first compound of this class, bisphenol A, is burdened by numerous reports of its potential toxicity and has been hence replaced by its analogues, so-called next generation bisphenols. Their widespread use has made them pervasive throughout the environment. These endocrine disrupting chemicals can affect the cardiovascular system, and hence the aim of this study was to test 14 bisphenols (A, AF, AP, B, BP, C, E, F, G, M, P, PH, S and Z), and compare their effects in vitro (human and rat cell lines), ex vivo (isolated rat aorta) and in vivo (Wistar Han rats, acutely or chronically exposed to low environmental and high toxic doses). The majority of the tested bisphenols relaxed rat aorta, but their potency varied markedly. The most potent compound, bisphenol AF, had an EC₅₀ of 57 μM. The mechanism of action was likely based on the inhibition of calcium influx via L-type calcium channels. The cytotoxicity of bisphenols towards 4 human and rat cell lines (H9c2, A-10, MCF7/S0.5 and MCF7/182R-6) showed variable potencies ranging from units of micromolar to millimolar concentrations. Based on these data, an effect on arterial blood pressure and possible cardiotoxicity was expected. Contrarily, the in vivo acute effects of three doses (0.005, 0.05 and 2.5 mg/kg) of bisphenol AF and 3 other analogues (A, S and F) on the cardiovascular system were rather biologically negligible. The most potent bisphenol, AF, was also administered chronically at a dose of 2.5 mg/kg for 4 weeks to rats, but had no impact on arterial blood pressure. Our results showed that bisphenols can relax vascular smooth muscles, but the effective concentrations are too high to produce clear cardiovascular effects in relation to common biological exposure as was confirmed with the most potent bisphenol AF.

A critical review of presence, removal and potential impacts of endocrine disruptors bisphenol A

Bisphenol A (BPA) is a synthetic organic compound that is mainly used in the production of polymer materials polycarbonate and epoxy resin. Widespread use and irregular processing methods have led to BPA being detected globally, raising concerns about its environmental and health effects. This review outlines an overview of the presence and removal of BPA in the environment and consumer products. We also summarized the endocrine-disrupting toxicity of BPA, and the relatively less summarized neurotoxicity, cytotoxicity, reproductive toxicity, genotoxicity, and carcinogenicity. Human exposure data show that humans have been exposed to low concentrations of BPA for a long time, future research should focus on the long-term exposure and the migration of BPA from consumer products to humans and the possible health risks associated with human exposure to BPA. Exploring economical and effective methods to reduce and remove BPA from the environment is imperative. The development of safe, functional and reproducible BPA analogs and the study of its degradation products can be the focus of subsequent research.

Enzymatic probe sonication for quick extraction of total bisphenols from animal-derived foods: Applicability to occurrence and exposure assessment

A high demand exists in bisphenols (BPs) screening studies for quick, reliable and straightforward analytical methods that generate data faster and simultaneously. Herein, we describe a combination of enzymatic probe sonication (EPS) and ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) for quick extraction and simultaneous quantification of eight important BPs in animal-derived foods. Results obtained demonstrated that the ultrasonic probe power could not only enhance the enzymatic hydrolysis efficiency, but also accelerate the liquid-liquid extraction procedure. Under optimized EPS parameters, one sample could be exhaustively extracted within 120 s, as compared with 12 h needed for the conventional enzymatic extraction which is more suitable for high-throughput analysis. The method was successfully applied to analyze residual BPs in animal-derived foods collected from Beijing, China. Widespread occurrence of BPA, BPS, BPF, BPAF, BPP, and BPB were found, with detection frequencies of 65.2%, 42.4%, 33.7%, 29.4%, 28.3%, and 27.2%, respectively. The highest total concentration levels of BPs (sum of the eight BPs analyzed, ΣBPs) were found in chicken liver (mean 12.2 μg/kg), followed by swine liver (6.37 μg/kg), bovine muscle (3.24 μg/kg), egg (2.03 μg/kg), sheep muscle (2.03 μg/kg), chicken muscle (1.45 μg/kg), swine muscle (1.42 μg/kg), and milk (1.17 μg/kg). The estimated daily intake (EDI) of BPs, based on the mean and 95th percentile concentrations and daily food consumptions, was estimated to be 5.687 ng/kg bw/d and 22.71 ng/kg bw/d, respectively. The human health risk assessment in this work suggests that currently BPs do not pose significant risks to the consumers because the hazard index (HI) was <1.

Photochemical reaction kinetics and mechanism of bisphenol A with K2S2O8 in aqueous solution: a laser flash photolysis study

The photochemical reaction kinetics and mechanism of bisphenol A (BPA) with potassium persulfate (K2S2O8) were investigated by using 266 nm laser flash photolysis and gas chromatography mass spectrum (GC-MS) technique. Sulfate radical (SO4•−), generated upon K2S2O8 photolysis, reacted with BPA with the overall rate constant of (1.61 ± 0.15) × 109 L mol−1 s−1, and two main reaction mechanisms were involved. One was addition channel to generate BPA–SO4•− adduct with a specific second-order rate constant of (1.09 ± 0.15) × 109 L mol−1 s−1. Molecular oxygen was involved in the decay of the BPA–SO4•− adduct with a rate constant of (1.28 ± 0.14) × 108 L mol−1 s−1. Another channel was the formation of BPA’s phenoxyl radical, likely derived from a deprotonation of the cation radical (BPA•+) generated from single electron transfer reactions. The specific rate constant of BPA’s phenoxyl radical formation was determined to be (6.16 ± 0.08) × 108 L mol−1 s−1. The overall rate constant was in line with the sum of aforementioned two specific rate constants for two main reaction channels. By comparing these rate constants, it was indicated that SO4•− addition channel accounted for ∼65% (1.09/1.61) to the overall reaction, and phenoxyl radical formation accounted for only ∼35% (0.62/1.61). The transformation products of BPA were identified by using GC-MS including 4-isopropylphenol, 4-isopropenylphenol, and 2,4-di-tert-butylphenol, and the reaction mechanism was proposed. These results may provide microscopic kinetics and mechanism information on BPA degradation using SO4•−-based advanced oxidation processes.

Maternal Bisphenol S exposure affects the reproductive capacity of F1 and F2 offspring in mice

Bisphenol S (BPS) is an endocrine disruptor which is widely used in commercial plastic products. Previous studies have shown that exposure to BPS has toxic effects on various aspects of mammalian, but there are few reports about reproductive toxicity. In order to investigate the effects of maternal BPS exposure on the reproductive of F1 and F2 female mice, the pregnant mice were orally administered with different dosages of BPS only once every day from 12.5 to 15.5 days post-coitus (dpc). The results showed that maternal BPS exposure to 2 μg per kg of body weight per day (2 μg/kg) and 10 μg/kg accelerated the meiotic prophase I (MPI) of F1 female mice and the expression of the genes related to meiotic were increased. Further studies showed that maternal BPS exposure resulted in a significant increase in the percentage of oocytes enclosed in primordial follicles in the 3 days post-partum (3 dpp) ovaries of F1 female mice. And at the time of 21 days post-partum (21 dpp) in F1 female mice, the number of antral follicles were significantly lower compare to controls. In the study of five-week female mice of F1, we found that BPS disturbed the folliculogenesis, and the maturation rates and fertilization rates of oocytes were significantly decreased. Of note, maternal BPS exposure disrupted H3K4 and H3K9 tri-methylation levels in F1 ovaries. Maternal BPS exposure only affected the cyst breakdown in F2 female mice. Taken together, our results suggest that, maternal BPS exposure impaired the process of meiosis and oogenesis of F1 and F2 offspring, resulting in abnormal follicular development and serious damage to the reproduction.

Occurrence of bisphenol A and its alternatives in paired urine and indoor dust from Chinese university students: Implications for human exposure

Bisphenol analogs (BPs), as the industrial chemicals, are widely used in consumer products. Limited information exists regarding human exposure to BPs in university students in China. In this study, we detected concentrations of seven BPs, namely bisphenol A (BPA), bisphenol AF (BPAF), bisphenol P (BPP), bisphenol AP (BPAP), bisphenol Z (BPZ), bisphenol S (BPS), and bisphenol F (BPF), in paired urine (n = 160) and indoor dust samples (n = 40) from university students in South China. High detection rates and levels (median) was found in BPA in paired urine (99%, 3.57 ng/mL) and indoor dust (80%, 2.98 μg/g) samples, followed by BPS (88%, 0.24 ng/mL; 78%, 0.22 μg/g). These findings suggest that BPA remains the major BPs used in consumer products. A positive relationship between urinary ∑BPs (sum of six BPs) concentration and indoor dust was observed (r = 0.444, p < 0.01), indicated that exposure to non-dietary BPs may also be significant to human exposure. The median EDI_urine values (ng/kg bw/day) of ∑BPs in males (119.6) were relatively higher than (p < 0.05) those in females (84.6). By contrast, the median EDI_dust of BPs (except for BPAF) in dust form female dormitories were slightly higher than that in dust from male dormitories. Notably, BPF was the most ingested from indoor dust (dormitory dust). This study is the first time to document the occurrence of BPs in paired urine and indoor dust in university students from China.

Bisphenol A and its substitutes regulate human B cell survival via Nrf2 expression

B cells contribute to produce inflammatory cytokines and antibodies, to present autoantigens, and to interact with T cells, which lead to body defense and disease control. Nuclear factor (erythroid-derived 2)-like 2(Nrf2) is responsible for gene expression of antioxidant enzymes to protect cells from oxidative stress by reactive oxygen species(ROS) production. Bisphenol A(BPA) may not be safe due to the effect on body's physiological functions. The chemicals that substitute for BPA may still have similar effects in the body. Tritan™ copolyester is a novel plastic form using BPA substitutes, 1,4-cyclohexanedimethanol(CHDM), dimethyl terephthalate(DMT), and 2,2,4,4-tetramethyl-1,3-cyclobutanediol(TMCD). Isosorbide(ISO) was also used as a substitute for TMCD and DMT. Here, we investigated whether B cell viability is influenced by BPA and its substitutes via Nrf2 induction using WiL2-NS human B lymphoblast cells. When cytotoxicity was measured by using assays with MTT, CellTiter-Glo, trypan blue and propidium iodide, cytotoxicity by BPA was higher than that by substitutes. BPA and its substitutes showed significant cytotoxicity and ROS production, which were attenuated by the treatment with N-acetylcysteine(NAC), a ROS scavenger. In addition, BPA treatment enhanced gene expression of antioxidant enzymes, heme oxygenase(HO)-1, catalase, superoxide dismutase(SOD) 1 and 2. As H₂O₂ treatment induced cell death and Nrf2 amount in WiL2-NS cells, BPA treatment increased Nrf2. Cell death by H₂O₂ was increased in doxycycline-inducible Nrf2-knockdown(KD) cells. In Cytotoxicity by the treatment with BPA or its substitutes was also enhanced in Nrf2-KD cells but that was reduced by Nrf2 overexpression compared to control cells. Taken together, these results implicate that B cell cytotoxicity by substitutes should be lower than BPA and Nrf2 can prevent B cells from BPA- or BPA substitutes-induced cytotoxicity via ROS production. Data suggest that the comprehensive studies or evaluation could be necessary to replace BPA in manufacture by other substitutes.

Redox-Sensitive and Hyaluronic Acid-Functionalized Nanoparticles for Improving Breast Cancer Treatment by Cytoplasmic 17α-Methyltestosterone Delivery

Novel reduction-responsive hyaluronic acid–chitosan–lipoic acid nanoparticles (HACSLA-NPs) were designed and synthesized for effective treatment of breast cancer by targeting Cluster of Differentiation 44 (CD44)-overexpressing cells and reduction-triggered 17α-Methyltestosterone (MT) release for systemic delivery. The effectiveness of these nanoparticles was investigated by different assays, including release rate, 3-(4,5-Dimethylthiazol-2-Yl)-2,5-Diphenyltetrazolium Bromide (MTT), lactate dehydrogenase (LDH), caspase-3 activity, Rhodamine 123 (RH-123), and Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL). In vitro experiments revealed that Methyltestosterone/Hyaluronic acid–chitosan–lipoic acid nanoparticles (MT/HACSLA-NPs) illustrated a sustained drug release in the absence of glutathione (GSH), while the presence of GSH led to fast MT release. HACSLA-NPs also showed high cellular internalization via CD44 receptors, quick drug release inside the cells, and amended cytotoxicity against positive CD44 BT-20 breast cancer cell line as opposed to negative CD44, Michigan Cancer Foundation-7 (MCF-7) cell line. These findings supported that these novel reduction-responsive NPs can be promising candidates for efficient targeted delivery of therapeutics in cancer therapy.

Synthesis and characterization of BPA-free polyesters by incorporating a semi-rigid cyclobutanediol monomer

A trans-1,3-cyclobutane-containing diol (CBDO-1) has been synthesized and introduced to materials science as a versatile monomer and a possible phenol-free BPA replacement.

Short and long-term effects of bisphenol S (BPS) exposure during pregnancy and lactation on plasma lipids, hormones, and behavior in rats

Bisphenol S (BPS) has replaced bisphenol A (BPA), a known non-persistent endocrine disrupting chemical, in several products. Considering that little is known regarding BPS effects, especially during critical windows of ontogenetic development, and that BPA, which is quite similar to BPS, is know to be transferred to the offspring via the placenta and milk, in the present study we investigated the behavioral, biochemical and endocrine profiles of Wistar rats born from dams that were BPS-exposed [groups: BPS10 (10 μg/kg/day), BPS50 (50 μg/kg/day)] during pregnancy and lactation. Due to the non-monotonic dose-response effect of bisphenol, the data of both BPS groups were directly compared with those of the controls, not to each other. Males and females were analyzed separately. At weaning, male BPS50 offspring had hypotriglyceridemia and hyperthyroxinemia, whereas BPS50 females showed higher 25(OH)D levels. At adulthood, BPS offspring of both sexes had lower food intake. BPS males showed lower visceral adiposity. BPS50 females had smaller fat droplets in brown adipocytes. BPS males showed higher anxiety and higher locomotor activity, while BPS10 females showed lower exploration. During a food challenge test at adulthood, BPS males consumed more high-fat diet at 30 min. BPS10 females initially (at 30 min) consumed more high-fat diet but, after 12 h, less of this diet was consumed. BPS50 males had hypertriglyceridemia and lower plasma T3, while BPS females showed lower plasma T4. BPS10 females had lower progesterone, whereas BPS50 females had higher plasma 25(OH)D. Maternal BPS exposure has adverse effects on the triacylglycerol, hormones levels and behavior of the progeny. Furthermore, the increased preference for the fat-enriched diet suggests an increased risk for obesity and its health consequences in the long term.

Biodegradation and detoxification of bisphenol A by bacteria isolated from desert soils

The endocrine-disrupting chemical bisphenol A (BPA) has attracted much attention because of its estrogenic activity and widespread environmental contamination. In this study, we investigated the BPA biodegradation abilities of various bacterial strains isolated from deserts and arid soils from southern Tunisia. Ten bacterial strains that belong to Pseudomonas putida, Pseudomonas aeruginosa, Enterobacter cloacae, Klebsiella sp. and Pantoea sp. showed high BPA removal potential in mineral salt medium (MSM) containing 1 mM BPA. BPA removal rates varied between strains and ranged from 36 to 97%. The strain G320 (P. putida) presented the highest BPA removal rate with 97% within 4 days at 30 °C. The half-life when increasing the BPA concentration to 3 mM was 2 days for strain G320, while total degradation was achieved within 8 days. BPA biodegradation products were identified by GC-MS, and their toxicity was assessed by an algal toxicity test. BPA detoxification was confirmed by evaluating the effect of its biodegradation metabolites on algal growth (dry weight), cells morphology and chlorophylls levels of Tetraselmis sp. strain V2. Results showed the interesting potential of desert soil's bacteria in BPA detoxification as well as the eventual use of the algal specie in toxicity assessment.