Lignin-derivable alternatives to bisphenol A with potentially undetectable estrogenic activity and minimal developmental toxicity

Lignin-derivable bisguaiacols/bissyringols are viable alternatives to commercial bisphenols; however, many bisguaiacols/bissyringols (e.g., bisguaiacol F [BGF]) have unsubstituted bridging carbons between the aromatic rings, making them more structurally similar to bisphenol F (BPF) than bisphenol A (BPA) - both of which are suspected endocrine disruptors. Herein, we investigated the estrogenic activity (EA) and developmental toxicity of dimethyl-substituted bridging carbon-based lignin-derivable bisphenols (bisguaiacol A [BGA] and bissyringol A [BSA]). Notably, BSA showed undetectable EA at seven test concentrations (from 10-12 M to 10-6 M) in the MCF-7 cell proliferation assay, whereas BPA had detectable EA at five concentrations (from 10-10 M to 10-6 M). In silico results indicated that BSA had the lowest binding affinity with estrogen receptors. Moreover, in vivo chicken embryonic assay results revealed that lignin-derivable monomers had minimal developmental toxicity vs. BPA at environmentally relevant test concentrations (8.7-116 μg/kg). Additionally, all lignin-derivable compounds showed significantly lower expression fold changes (from ∼1.81 to ∼4.41) in chicken fetal liver tests for an estrogen-response gene (apolipoprotein II) in comparison to BPA (fold change of ∼11.51), which was indicative of significantly reduced estrogenic response. Altogether, the methoxy substituents on lignin-derivable bisphenols appeared to be a positive factor in reducing the EA of BPA alternatives.

Bombesin-like receptor 3 expression induced by bisphenol A is likely associated with reduced cell proliferation by inhibiting DNA synthesis and inducing inflammation in liver cells

BACKGROUND

Bisphenol A (BPA) is an exogenous endocrine disruptor mimicking hormones closely associated with health complications, such as cancer progression. BPA is also related to an increase in the prevalence of obesity-related diseases due to its obesogenic action. Bombesin-like receptor 3 (BRS3) is an important factor that should be considered in the adipogenic gene network, as depletion of this gene alters adiposity.

METHODS

Therefore, the present study aimed to investigate the messenger ribonucleic acid (mRNA) expression of BRS3 in human liver THLE-2 cells post-BPA treatment by real-time polymerase chain reaction. The effects of BPA on the levels of pro-inflammatory proteins, interleukin 6 (IL6) and CC motif chemokine ligand 2 (CCL2), in conditioned media of BPA-treated THLE-2 cells and deoxyribonucleic acid (DNA) synthesis in replicating BPA-treated THLE-2 cells during the cell cycle were also examined by enzyme-linked immunosorbent assay (ELISA) and flow cytometry, respectively.

RESULTS

The study found that the mRNA expression of BRS3 was increased in THLE-2 cells treated with BPA. The study also showed that the expression levels of IL6 and CCL2 reached an optimum level in the conditioned media of BPA-treated THLE-2 cells after 48 h of treatment. Subsequently, the DNA synthesis analysis showed that bromodeoxyuridine/propidium iodide (BrdU/PI) stained positive cells were decreased in BPA-treated THLE-2 cells at 72 h of treatment.

CONCLUSION

The study demonstrates that BRS3 expression induced by BPA is likely associated with reduced cell proliferation by inhibiting DNA synthesis and inducing cellular inflammation in liver cells.

Bisphenol A (BPA) exposure aggravates hepatic oxidative stress and inflammatory response under hypertensive milieu - Impact of low dose on hepatocytes and influence of MAPK and ER stress pathways

Human exposure to the hazardous chemical, Bisphenol A (BPA), is almost ubiquitous. Due to the prevalence of hypertension (CVD risk factor) in the aged human population, it is necessary to explore its adverse effect in hypertensive subjects. The current study exposed the Nω-nitro-l-arginine methyl ester (L-NAME) induced hypertensive Wistar rats to human exposure relevant low dose of BPA (50 μg/kg) for 30 days period. The liver biochemical parameters, histopathology, immunohistochemistry, gene expression (RT-qPCR), trace elements (ICP-MS), primary rat hepatocytes cell culture and metabolomic (1H NMR) assessments were performed. Results illustrate that BPA exposure potentiates/aggravates hypertension induced tissue abnormalities (hepatic fibrosis), oxidative stress, ACE activity, malfunction of the antioxidant system, lipid abnormalities and inflammatory factor (TNF-α and IL-6) expression. Also, in cells, BPA increased ROS generation, mitochondrial dysfunction and lipid peroxidation without any impact on cytotoxicity and caspase 3 and 9 activation. Notably, BPA exposure modulate lipid metabolism (cholesterol and fatty acid) in primary hepatocytes. Finally, the influence of ERK1/2, p38MAPK, ER stress and oxidative stress during relatively high dose of BPA elicited cytotoxicity was observed. Therefore, a precise hazardous risk investigation of BPA exposure in hypertensive populations is highly recommended.

Zinc Deficiency Exacerbates Bisphenol A-Induced Hepatic and Renal Damage: Delineation of Molecular Mechanisms

Zinc (Zn) plays an important role in the maintenance of redox status in the biological system. Zn deficiency has been found to be associated with negative effects on the functioning of many organ systems, including hepatic and renal systems. Bisphenol A (BPA) can alter Zn homeostasis and perturb the physiological system by provoking oxidative stress, which can lead to damage of different organs such as reproductive, immune, neuroendocrine, hepatic and renal systems. The present study aims to investigate the toxicity of BPA in Zn deficient condition in the liver and kidney of rat and to correlate its synergistic actions. Zn deficiency was induced by feeding Zn-deficient diet (ZDD), and BPA was administered orally (100 mg/kg/d). Male Sprague-Dawley rats were divided into four groups: NPD + Vehicle (normal feed and water), NPD + BPA (100 mg/kg/d), ZDD + Vehicle (fed with Zn-deficient diet only) and ZDD + BPA (Zn-deficient diet + BPA; 100 mg/kg/d) for 8 weeks. Biochemical, histopathological, TUNEL assay and protein expression profiles were determined to decipher the oxidative damage induced by ZDD and the toxicant BPA. Expression profile of nuclear factor erythroid 2-related factor 2, proliferating cell nuclear antigen, kelch-like ECH-associated protein 1, superoxide dismutase-1, metallothionein and apoptosis incidence showed that ZDD and BPA have a synergistic exacerbation effect on the liver and kidney of rat.

Combined Toxic Effects of BPA and Its Two Analogues BPAP and BPC in a 3D HepG2 Cell Model

Bisphenol A (BPA) is one of the most commonly used substances in the manufacture of various everyday products. Growing concerns about its hazardous properties, including endocrine disruption and genotoxicity, have led to its gradual replacement by presumably safer analogues in manufacturing plastics. The widespread use of BPA and, more recently, its analogues has increased their residues in the environment. However, our knowledge of their toxicological profiles is limited and their combined effects are unknown. In the present study, we investigated the toxic effects caused by single bisphenols and by the combined exposure of BPA and its two analogues, BPAP and BPC, after short (24-h) and prolonged (96-h) exposure in HepG2 spheroids. The results showed that BPA did not reduce cell viability in HepG2 spheroids after 24-h exposure. In contrast, BPAP and BPC affected cell viability in HepG2 spheroids. Both binary mixtures (BPA/BPAP and BPA/BPC) decreased cell viability in a dose-dependent manner, but the significant difference was only observed for the combination of BPA/BPC (both at 40 µM). After 96-h exposure, none of the BPs studied affected cell viability in HepG2 spheroids. Only the combination of BPA/BPAP decreased cell viability in a dose-dependent manner that was significant for the combination of 4 µM BPA and 4 µM BPAP. None of the BPs and their binary mixtures studied affected the surface area and growth of spheroids as measured by planimetry. In addition, all BPs and their binary mixtures studied triggered oxidative stress, as measured by the production of reactive oxygen species and malondialdehyde, at both exposure times. Overall, the results suggest that it is important to study the effects of BPs as single compounds. It is even more important to study the effects of combined exposures, as the combined effects may differ from those induced by single compounds.

Morphological, immunohistochemical, and biochemical study on the ameliorative effect of gallic acid against bisphenol A-induced nephrotoxicity in male albino rats

This study aimed to determine the effect of gallic acid (GA) on ameliorating bisphenol A (BPA) nephrotoxicity in male rat kidneys. Forty rats were assigned randomly into two groups: control (ten animals) and BPA (40 mg/kg bwt) (thirty animals), the second group was divided into three subgroups: BPA alone, BPA + G50 (50 mg/kg bwt), and BPA + G200 (200 mg/kg bwt). The biochemical analysis included measurements of the contents of nitric oxide, lipid peroxidation, reactive oxygen species, and cytokines (interleukin-1α and interleukin-6) in the kidney. The antioxidant enzymes catalase and superoxide dismutase were also measured in the kidney. Kidney function was assessed by determining uric acid, urea, and creatinine levels. The morphological investigations included hematoxylin and eosin staining for assessing the general histology and determining the glomerular and corpuscular areas, the tubular cell degeneration mean area, and the mean leukocyte infiltration area. Also, collagen fiber intensity and polysaccharide content were analyzed. Furthermore, immunohistochemical, morphometric, and ultrastructural studies were carried out. The results revealed morphological, immunohistochemical, and biochemical alterations in the kidney. Most of these changes showed a satisfactory improvement of kidney damage when BPA-administered rats were treated with GA at both doses. In conclusion, GA exhibited a strong protective effect against BPA-induced nephrotoxicity.

RNA-sequencing analysis of bisphenol A biodegradation by white-rot fungus Phanerochaete sordida YK-624

Bisphenol A (BPA) is a representative example of an endocrine-disrupting chemical. It is one of the most produced chemical substances in the world, but it causes harmful effects in organisms, such that the effective degradation of BPA is critical. The white-rot fungus Phanerochaete sordida YK-624 has been shown to effectively degrade BPA under ligninolytic and non-ligninolytic conditions. However, it is still unclear what kinds of enzymes are involved in BPA degradation. To explore the mechanism of BPA degradation, the present study analysed the functional genes of P. sordida YK-624 using RNA-sequencing (RNA-Seq). Oxidation-reduction process and metabolic pathway were enriched under ligninolytic and non-ligninolytic conditions by Gene Ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis. It is suggested that BPA might be used as a carbon source by P. sordida YK-624. Lignin peroxidase and cytochrome P450 were detected in upregulated differentially expressed genes (DEGs). The lignin-degrading enzyme lignin peroxidase and the intracellular cytochrome P450 system were involved in BPA degradation by P. sordida YK-624, respectively. Furthermore, quantitative real-time PCR (qPCR) was used to validate the reliability of the RNA-Seq results.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-022-03298-w.

Adverse Effects of Bisphenol A on the Liver and Its Underlying Mechanisms: Evidence from In Vivo and In Vitro Studies

BPA is a known endocrine-disrupting agent that is capable of binding to the estrogen receptor and has exhibited adverse effects in many laboratory animal and in vitro studies. Moreover, it also been shown to have estrogenic, antiandrogenic, inflammatory, and oxidative properties. The widespread presence of BPA in the environment presents a considerable threat to humans. BPA has been shown to be leached into the human ecosystem, where it is commonly found in food products consumed by humans. Although the concentration is relatively low, its prolonged consumption may cause a variety of deleterious health effects. The liver is an important organ for metabolizing and detoxifying toxic metabolites to protect organisms from potentially toxic chemical insults. BPA that is ingested will be eliminated by the liver. However, it has also induced hepatoxicity and injury via various mechanisms. To find research demonstrating the effects of BPA on kidney, a number of databases, including Google Scholar, MEDLINE, PubMed, and the Directory of Open Access Journals, were searched. Thus, this review summarizes the research on the relationship between BPA and its effects on the liver-derived from animals and cellular studies. The underlying mechanism of liver injury caused by BPA is also elucidated.

A review: Systematic research approach on toxicity model of liver and kidney in laboratory animals

Therapeutic experiments are commonly performed on laboratory animals to investigate the possible mechanism(s) of action of toxic agents as well as drugs or substances under consideration. The use of toxins in laboratory animal models, including rats, is intended to cause toxicity. This study aimed to investigate different models of hepatotoxicity and nephrotoxicity in laboratory animals to help researchers advance their research goals. The current narrative review used databases such as Medline, Web of Science, Scopus, and Embase and appropriate keywords until June 2021. Nephrotoxicity and hepatotoxicity models derived from some toxic agents such as cisplatin, acetaminophen, doxorubicin, some anticancer drugs, and other materials through various signaling pathways are investigated. To understand the models of renal or hepatotoxicity in laboratory animals, we have provided a list of toxic agents and their toxicity procedures in this review.

Toxicological assessment of low-dose bisphenol A, lead and endosulfan combination: chronic toxicity study in male rats

In the present study, toxic effects, both alone and combined, of bisphenol A (BPA), lead (Pb) and endosulfan (ES) in the low doses were investigated in rat liver and kidney functions. In the study, bisphenol A (BPA), lead (Pb) and endosulfan (ES) were chosen because although they are the chemicals people are most frequently exposed to, no combined toxic effect studies were conducted with these chemicals. Sixty-four male Wistar albino rats were used in the study, and they were randomly divided into eight groups (n = 8 per group); control, BPA (5 mg/kg), Pb (100 ppm), ES (0.61 mg/kg), BPA+Pb, BPA+ES, Pb+ES and BPA+P+ES. The rats were sacrificed after 65 days of treatment. Severe histopathological changes in the liver and kidney tissues were observed in the rats exposed to BPA+Pb+ES combination. Elevated malondialdehyde (MDA) in the liver and decreased superoxide dismutase activity (SOD) in the kidney tissue were detected in the BPA+Pb+ES group compared to those of the control group. It was found that serum alanine aminotransferase (ALT) and blood urea nitrogen (BUN) and creatinine (CREA) levels were higher in the BPA+Pb+ES combination group than the control group. Also, combined exposure of BPA, Pb and ES caused apoptotic cell numbers and inducible nitric oxide (iNOS) to increase in the liver and kidney tissues. The results of the present study suggested that the BPA, Pb and ES caused more dramatic changes to both histological architecture and cell apoptosis in the liver and kidney tissues when there was a combined exposure.

Chronic exposure to nonylphenol induces oxidative stress and liver damage in male zebrafish (Danio rerio): Mechanistic insight into cellular energy sensors, lipid accumulation and immune modulation

Nonylphenol (NP), an environmentally persistent and toxic endocrine-disrupting chemical with estrogenic properties, has severe implications on humans and wildlife. Accumulating evidence demonstrates the toxic response of NP on the developmental process, nervous system, and reproductive parameters. Although NP exposure has been implicated in chronic liver injury, the underlying events associated with hepatic pathophysiology remain less investigated. Using male zebrafish (Danio rerio) as the model, the present study investigates the impact of environmentally relevant concentrations of NP (50 and 100 μg/L, 21 days) on hepatic redox homeostasis vis-à-vis cellular energy sensors, inflammatory response, and cell death involving a mechanistic insight into estrogen receptor (ER) modulation. Our results demonstrate that congruent with significant alteration in transcript abundance of antioxidant enzymes (SOD1, SOD2, Catalase, GPx1a, GSTα1), chronic exposure to NP promotes ROS synthesis, more specifically superoxide anions and H₂O₂ levels, and lipid peroxidation potentially through elevated NOX4 expression. Importantly, NP perturbation of markers associated with fatty acid biosynthesis (srebf1/fasn) and cellular energy-sensing network (sirt1/ampkα/pgc1α) indicates dysregulated energy homeostasis, metabolic disruption, and macrovesicular steatosis, albeit with differential sensitivity at the dose level tested. Besides, elevated p38-MAPK phosphorylation (activation) together with loss of ER homeostasis at both mRNA (esr1, esr2a, esr2b) and protein (ERα, ERβ) levels suggest that NP modulation of ER abundance may have a significant influence on hepatic events. Elevated expression of inflammatory markers (TLR4, p-NF-κB, TNF-α, IL-6, IL-1β, and NOS2) and pro-apoptotic and necrotic regulators, e.g., Bax, caspase- 8, -9 and cleaved PARP1 (50 kDa), indicate chronic inflammation and hepatotoxicity in NP-exposed males. Collectively, elevated oxidative stress, metabolic dysregulation and immune modulation may lead to chronic liver injury in organisms exposed to metabolic disrupting chemicals.

Bisphenol A exposure induces apoptosis and impairs early embryonic development in Xenopus laevis

Bisphenol A (BPA), an endocrine-disrupting chemical that is largely produced and used in the plastics industry, causes environmental pollution and is absorbed by humans through consumption of food and liquids in polycarbonate containers. BPA exerts developmental and genetic toxicities to embryos and offsprings, but the embryotoxicity mechanism of this chemical is unclear. This study aimed to explore the toxic effect of BPA on embryonic development and elucidate its toxicity mechanism. Embryos of Xenopus laevis as a model were treated with different concentrations (0.1, 1, 10, and 20 μM) of BPA at the two-cell stage to investigate the developmental toxicity of BPA. Embryonic development and behaviors were monitored 24 h-96 h of BPA exposure. BPA concentrations greater than 1 μM exerted significant teratogenic effects on the Xenopus embryos, which showed short tail axis, miscoiled guts, and bent notochord as the main malformations. The 20 μM BPA-treated embryos were seriously damaged in all aspects and exhibited deformity, impaired behavioral ability, and tissue damage. The DNA integrity and apoptosis of the Xenopus embryos were also investigated. Exposure to BPA concentrations higher than 0.1 μM significantly induced DNA damage (p < 0.05). The 10 and 20 μM BPA-treated embryos exhibited higher levels of cleaved caspase-3 protein than the control. The ratios of bax/bcl-2 mRNA were significantly higher in the 10 μM and 20 μM-treated embryos than the ratio in the control group. Overall, data indicated that BPA can delay the early development, induce DNA damage and apoptosis, and eventually cause multiple malformations in Xenopus embryos.

Bisphenol A and Type 2 Diabetes Mellitus: A Review of Epidemiologic, Functional, and Early Life Factors

Type 2 diabetes mellitus (T2DM) is characterised by insulin resistance and eventual pancreatic β-cell dysfunction, resulting in persistent high blood glucose levels. Endocrine disrupting chemicals (EDCs) such as bisphenol A (BPA) are currently under scrutiny as they are implicated in the development of metabolic diseases, including T2DM. BPA is a pervasive EDC, being the main constituent of polycarbonate plastics. It can enter the human body by ingestion, through the skin, and cross from mother to offspring via the placenta or breast milk. BPA is a xenoestrogen that alters various aspects of beta cell metabolism via the modulation of oestrogen receptor signalling. In vivo and in vitro models reveal that varying concentrations of BPA disrupt glucose homeostasis and pancreatic β-cell function by altering gene expression and mitochondrial morphology. BPA also plays a role in the development of insulin resistance and has been linked to long-term adverse metabolic effects following foetal and perinatal exposure. Several epidemiological studies reveal a significant association between BPA and the development of insulin resistance and impaired glucose homeostasis, although conflicting findings driven by multiple confounding factors have been reported. In this review, the main findings of epidemiological and functional studies are summarised and compared, and their respective strengths and limitations are discussed. Further research is essential for understanding the exact mechanism of BPA action in various tissues and the extent of its effects on humans at environmentally relevant doses.

Bisphenol A induces apoptosis through GPER-dependent activation of the ROS/Ca2+-ASK1-JNK pathway in human granulosa cell line KGN

Bisphenol A (BPA) is widely distributed in the environment and human surroundings and is closely related to the occurrence of many chronic diseases including female infertility. Although BPA-induced granulosa cell apoptosis has been widely reported, the underlying mechanisms remain unknown. In this study, we evaluated the induction effect of BPA exposure on apoptosis and mechanisms of regulation in KGN cells (a human granulosa-like tumor cell line). Our results indicated that BPA induced apoptosis of KGN cells in a dose- and time-dependent manner. BPA exposure significantly promoted the expression of pro-apoptotic proteins and decreased mitochondrial membrane potential. We also observed that high concentrations of BPA significantly promoted the generation of reactive oxygen species (ROS) and calcium ion (Ca²⁺) accumulation. The involvement of ROS and Ca²⁺ in BPA-induced KGN cell apoptosis was confirmed by pretreatment with NAC (an antioxidant) and BAPTA-AM (a calcium chelator). After inhibitors pretreatment to block the corresponding signaling pathways, it was found that BPA-induced phosphorylation of JNK and ASK1 proteins and apoptosis of KGN cells were significantly inhibited. We pretreated with G15 (a GPER inhibitor) and found that BPA-induced ROS generation and Ca²⁺ accumulation and apoptosis were significantly inhibited. These results suggest that BPA exposure induces KGN cell apoptosis through GPER-dependent activation of the ROS/Ca²⁺-ASK1-JNK signaling pathway. Our study provides mechanisms by which BPA induced apoptosis of granulosa cells and ovarian dysfunction.

White rot fungi can be a promising tool for removal of bisphenol A, bisphenol S, and nonylphenol from wastewater

Endocrine-disrupting chemicals (EDC) are a wide group of chemicals that interfere with the endocrine system. Their similarity to natural steroid hormones makes them able to attach to hormone receptors, thereby causing unfavorable health effects. Among EDC, bisphenol A (BPA), bisphenol S (BPS), and nonylphenol (NP) seem to be particularly harmful. As the industry is experiencing rapid expansion, BPA, BPS, and NP are being produced in growing amounts, generating considerable environmental pollution. White rot fungi (WRF) are an economical, ecologically friendly, and socially acceptable way to remove EDC contamination from ecosystems. WRF secrete extracellular ligninolytic enzymes such as laccase, manganese peroxidase, lignin peroxidase, and versatile peroxidase, involved in lignin deterioration. Owing to the broad substrate specificity of these enzymes, they are able to remove numerous xenobiotics, including EDC. Therefore, WRF seem to be a promising tool in the abovementioned EDC elimination during wastewater treatment processes. Here, we review WRF application for this EDC removal from wastewater and indicate several strengths and limitations of such methods.

Bisphenol A-induced oxidative stress, hepatotoxicity and altered estrogen receptor expression in Labeo bata: impact on metabolic homeostasis and inflammatory response

Bisphenol A (BPA), a weak estrogenic endocrine disruptor and a well-known plasticizer, has the potential to perturb diverse physiological functions; however, its impact on immune and metabolic function in aquatic vertebrates is relatively less understood. The present study aims to investigate the impact of BPA on hepatotoxicity, metabolic and immune parameters vis-à-vis estrogen receptor expression modulation in a freshwater teleost, Labeo bata (Cyprinidae, Cypriniformes). The 96-h median lethal concentration of BPA in L. bata has been determined as 4.79 mg/L. Our data demonstrate that congruent with induction of plasma vitellogenin (VTG), chronic exposure to sub-lethal BPA (2 and 4 μM/L) attenuates erythrocyte count, hemoglobin concentration, packed cell volume, mean corpuscular hemoglobin, but not leukocyte number. Further, a significant increase in MDA, concomitant with diminished catalase and heightened GST activity corroborates well with hepatic dystrophic changes, appearance of fatty liver (macrovesicular steatosis) and elevated serum lipids (triglyceride, cholesterol, LDL, VLDL) in BPA-treated groups. Interestingly, a differential regulation of estrogen receptor (ER) subtypes at transcript and protein level signifies negative influence of BPA on hepatic ERα/ERβ homeostasis in this species. While at a lower dose it promotes Akt phosphorylation (activation), BPA at the higher dose attenuates ERK1/2 phosphorylation (activation), suggesting potential alteration in insulin sensitivity. Importantly, dose-dependent decrease in hepatic TNF-α, IL-1β, iNOS (NOS2) expression and nitric oxide (NO) level corresponds well with progressive decline in p-NF-κB, p-p38 MAPK, albeit with differential sensitivity, in BPA-exposed groups. Collectively, BPA exposure has wide-spread negative influence on hematological, biochemical and hepatic events in this species.

Role of Antioxidants in Alleviating Bisphenol A Toxicity

Bisphenol A (BPA) is an oestrogenic endocrine disruptor widely used in the production of certain plastics, e.g., polycarbonate, hard and clear plastics, and epoxy resins that act as protective coating for food and beverage cans. Human exposure to this chemical is thought to be ubiquitous. BPA alters endocrine function, thereby causing many diseases in human and animals. In the last few decades, studies exploring the mechanism of BPA activity revealed a direct link between BPA-induced oxidative stress and disease pathogenesis. Antioxidants, reducing agents that prevent cellular oxidation reactions, can protect BPA toxicity. Although the important role of antioxidants in minimizing BPA stress has been demonstrated in many studies, a clear consensus on the associated mechanisms is needed, as well as the directives on their efficacy and safety. Herein, considering the distinct biochemical properties of BPA and antioxidants, we provide a framework for understanding how antioxidants alleviate BPA-associated stress. We summarize the current knowledge on the biological function of enzymatic and non-enzymatic antioxidants, and discuss their practical potential as BPA-detoxifying agents.

Bisphenol A-induced metabolic disorders: From exposure to mechanism of action

Bisphenol A (BPA) is considered as ubiquitous xenooestrogen and an endocrine disrupting chemical which has deleterious effects on endocrine functions. Human populations are continuously exposed to BPA as it is abundant in daily life. It has been found to be associated with wide range of metabolic disorders notably type 2 diabetes mellitus (DM). Numerous epidemiological studies have been conducted to find its role in development of DM. Experimental studies have found that BPA exposure is associated with pathogenesis of DM and also considered as a risk factor for gestational diabetes. Being a lipophilic compound, BPA is preferably accumulated in adipose tissues where it alters the production of adipokines that play important roles in insulin resistance. BPA induces apoptosis by caspase activation after mitochondrial damage and it impairs insulin signaling pathways by altering associated ion channel activity especially potassium channels. Perinatal exposure of BPA makes offspring more susceptible to develop DM in early years. Epigenetic modifications are the key mechanisms for BPA-induced metabolic re-programming, where BPA alters the expression of DNA methyltransferases involved in methylation of various genes. In this way, DNA methyltransferase controls the expression of numerous genes including genes important for insulin secretion and signaling. Furthermore, BPA induces histone modifications and alters miRNA expression. In this article, we have briefly described the sources of BPA exposure to human being and summarized the evidence from epidemiological studies linking DM with BPA exposure. Additionally, we have also highlighted the potential molecular pathways for BPA-induced DM.

Hepatoprotective effects of curcumin and taurine against bisphenol A-induced liver injury in rats

Bisphenol A (BPA) is an estrogenic endocrine disrupting chemical to which humans are frequently exposed during routine daily life. Curcumin and taurine are natural products that have also been used as antioxidants against different environmental toxin-induced hepatotoxicity. Furthermore, they have protective and therapeutic effects against various diseases. The present investigation has been conducted to evaluate the therapeutic potential of curcumin (100 mg kg^-1) and taurine (100 mg kg^-1) for their hepatoprotective efficacy against BPA (130 mg kg^-1)-induced liver injury in rat. BPA significantly elevated the levels of malondialdehyde (MDA), while it reduced the activities of catalase (CAT), total glutathione S-transferase (GST), total glutathione peroxidase (GPx), and total superoxide dismutase (SOD). Besides, these biochemical changes were accompanied by histopathological alterations marked by the destruction of normal liver structure. The histological examinations showed that exposure of BPA caused dilatation of sinusoids, inflammatory cell infiltration, congestion, and necrosis in liver parenchyma. The BPA-induced histopathological alterations in liver were minimized by curcumin and taurine treatment. Furthermore, no necrosis was observed in the liver tissues of curcumin plus BPA and taurine plus BPA-treated rats. Oral administration of curcumin and taurine to BPA-exposed rats significantly reversed the content of lipid peroxidation products, as well as enhanced the activities of GPx and GST, CAT, and SOD enzymes. These findings have indicated that curcumin and taurine might have a protective effect against BPA-induced hepatotoxicity in rats.

Mitochondrial Involvement in the Adaptive Response to Chronic Exposure to Environmental Pollutants and High-Fat Feeding in a Rat Liver and Testis

In our modern society, exposure to stressful environmental stimuli, such as pollutants and/or chronic high-fat feeding, continuously induce tissular/organ metabolic adaptation to promote cellular survival. In extreme conditions, cellular death and tissular/organ damage occur. Mitochondria, as a cellular energy source, seem to play an important role in facing cellular stress induced by these environmental stimuli. On the other hand, mitochondrial dysfunction and oxidative stress play a key role in environmental stress-induced metabolic diseases. However, little is known about the combined effect of simultaneous exposure to chronic high-fat feeding and environmental pollutants on metabolic alterations at a tissular and cellular level, including mitochondrial dysfunction and oxidative stress induction. Our research group recently addressed this topic by analysing the effect of chronic exposure to a non-toxic dose of the environmental pollutant dichlorodiphenyldichloroethylene (DDE) associated with high-fat feeding in male Wistar rats. In this review, we mainly summarize our recent findings on mitochondrial adaptive response and oxidative stress induction in the liver, the main tissue involved in fat metabolism and pollutant detoxification, and in male gonads, the main targets of endocrine disruption induced by both high-fat feeding and environmental pollutants.

Bisphenol A analogues bisphenol B, bisphenol F, and bisphenol S induce oxidative stress, disrupt daily sperm production, and damage DNA in rat spermatozoa: a comparative in vitro and in vivo study

Bisphenol A (BPA) is a well-known endocrine-disrupting chemical with estrogenic activity. The widespread exposure of individuals to BPA is suspected to affect a variety of physiological functions, including reproduction, development, and metabolism. Here we report the mechanisms by which BPA and three of its analogues bisphenol B (BPB), bisphenol F (BPF), and bisphenol S (BPS) cause generation of reactive oxygen species (ROS), sperm DNA damage, and oxidative stress in both in vivo and in vitro rat models. Sperm were incubated with different concentrations (1, 10, and 100 µg/L) of BPA and its analogues BPB, BPF, and BPS for 2 h. BPA and its analogues were observed to increase DNA fragmentation, formation of ROS, and affected levels of superoxide dismutase at higher concentration groups. In an in vivo experiment, rats were exposed to different concentrations (5, 25, and 50 mg/kg/day) of BPA, BPB, BPF, and BPS for 28 days. In the higher dose (50 mg/kg/day) treated groups of BPA and its analogues BPB, BPF, and BPS, DNA damage was observed while the motility of sperm was not affected.

Lycopene: Hepatoprotective and Antioxidant Effects toward Bisphenol A-Induced Toxicity in Female Wistar Rats

Bisphenol A (BPA)—an endocrine disruptor xenoestrogen—is widely spread in the environment. Lycopene (LYC) is an antioxidant phytochemical carotenoid. The hereby study was designed to verify the deleterious effect of BPA on cyclic female rats' hepatic tissue as well as evaluation of the effect of LYC toward BPA hepatic perturbation. Twenty-eight female Wistar rats were allocated equally into four groups: control group, LYC group (10 mg/kg B.wt), BPA group (10 mg/kg B.wt), and BPA + LYC group (the same doses as former groups). The treatments were given daily via gavage to the rats for 30 days. The rats in BPA displayed high activities of serum liver enzymes with low levels of total proteins (TP) and albumin. Moreover, BPA induced hepatic oxidative stress via depletion of antioxidant enzymes concomitant with augmentation of lipid peroxidation, increased comet tail DNA %, and overexpression of caspase-3. Meanwhile, LYC administration reduced the cytotoxic effects of BPA on hepatic tissue, through improving the liver function biomarkers and oxidant-antioxidant state as well as DNA damage around the control values. These findings were confirmed by hepatic histopathological examination. Finally, LYC credited to have a noticeable protective effect versus BPA provoked oxidative injury and apoptosis of the liver tissue.

Comparative analysis of BPA and HQ toxic impacts on human erythrocytes, protective effect mechanism of tannins (Rhus typhina)

Several studies reported that bisphenol A (BPA) and its metabolite hydroquinone (HQ) have adverse effects on human and animal health. In this work, a comparative study of influence of the BPA and HQ, environment pollutants, on human erythrocytes was carried out. It was shown that BPA and HQ to varying extents caused oxidative damage in human erythrocytes: hemolysis, decreased GSH level, and methemoglobin formation. It was demonstrated that hydrolysable tannins 3,6-bis-O-di-O-galloyl-1,2,4-tri-O-galloyl-β-D-glucose (C₅₅H₄₀O₃₄) and 1,2,3,4,6-penta-O-galloyl-β-D-glucose (C₄₁H₃₂O₂₆) (PGG) isolated from the Rhus typhina L. leaves in the range of 1-50 μM concentrations inhibited hemolysis and methemoglobin formation and also increased intracellular reduced glutathione in erythrocytes treated with BPA or HQ. It was revealed by electron paramagnetic resonance (EPR) using 5-doxyl-stearic acid (5-DS) that C₅₅H₄₀O₃₄ and C₄₁H₃₂O₂₆ increased the rigidity of erythrocyte membranes at the depth of 5th carbon atom of the fatty acid hydrocarbon chain. Taken together, these results allow to conclude that tannins from the Rhus typhina L. leaves protect erythrocytes from oxidative stress caused by BPA or HQ both due to their antioxidant activity as well as their interaction with the erythrocyte membrane components.

Proteomics and phosphoproteomics analysis of liver in male rats exposed to bisphenol A: Mechanism of hepatotoxicity and biomarker discovery

Bisphenol A (BPA), discovered to be an artificial estrogen, has been shown to leach from some containers and mediate oxidative damage to cells and tissues and to be involved in reproductive disorders, obesity, diabetes, and liver dysfunction. In the current study, we investigated the effects of oral chronic exposure to low dose of BPA (0.5 mg kg^-1) on the protein and phosphoprotein expression profiles in male Wistar rat liver using a gel-based proteomics approach based on two-dimensional gel electrophoresis followed by matrix-assisted laser desorption/ionization mass spectrometry identification. Our results showed that BPA exposure affected the levels of proteins and phosphoproteins involved in diverse biological processes associated with hepatotoxicity, fatty liver, and carcinoma. Moreover, we analyzed the effects of BPA on oxidative stress by assessing levels of malondialdehyde (MDA), a marker of lipid peroxidation, and reduced glutathione (GSH), a non-enzymatic antioxidant agent, in the liver. As expected BPA induced oxidative stress indicated by increased levels of MDA and decreased GSH content in the liver. In conclusion, chronic oral exposure of rats to BPA leads to increased oxidative stress in the liver and major alterations in the liver proteome and phosphoproteome, which may contribute to the pathophysiology of liver diseases.

Fluorochloridone induces primary cultured Sertoli cells apoptosis: Involvement of ROS and intracellular calcium ions-mediated ERK1/2 activation

Fluorochloridone (FLC) is a widely used pyrrolidone selective herbicide and reported to induce testis injuries in male rats, but the underlying mechanism is largely unknown. In the present study, primary-cultured Sertoli cells were exposed to FLC at the concentration of 0-10.00μM to study the mechanism of FLC-induced apoptosis. The roles of ROS, intracellular calcium, endoplasmic reticulum (ER), and ERK1/2 were looked at with ROS scavenger N-acetyl-cysteine (NAC), intracellular calcium chelator BAPTA-AM, ER calcium depleting agent thapsigargin (TG), and ERK1/2 inhibitor U0126, respectively. FLC induced dose-dependent apoptosis increase as well as the elevation in levels of ROS, intracellular calcium, and ERK1/2 activation. FLC treatment led to constantly increasing apoptotic rates and ERK1/2 activation over time, while inversed-V shaped change tendencies of ROS and intracellular calcium levels were observed. FLC-induced ROS generation disrupted the intracellular calcium homeostasis by attacking the ER, and the elevated intracellular calcium levels resulted in ERK1/2 over-phosphorylation and consequently promoted Sertoli cell apoptosis. Taken together, ROS and intracellular calcium-mediated ERK1/2 activation led to FLC-induced Sertoli cell apoptosis.

Inflammation, oxidative stress and apoptosis cascade implications in bisphenol A-induced liver fibrosis in male rats

Bisphenol A (BPA) is a key monomer in the production of plastics. It has been shown to be hepatotoxic. Inflammation and oxidative stress are closely linked with liver fibrosis, the major contributing factor to hepatic failure. Therefore, the aim of this study was to evaluate the impact of chronic exposure to BPA on the development of hepatic fibrosis in male rats and to determine the cross-talk between the hepatic cytokine network, oxidative stress and apoptosis. For this purpose, 30 male Wistar albino rats were divided into three equal groups as follows: the first group was given no treatment (normal control group); the second group was given corn oil once daily by oral gavage for 8 weeks (vehicle control group); and the third group received BPA (50 mg/kg body weight/day, p.o.) for 8 weeks. BPA administration induced liver fibrosis as reflected in an increase in serum hepatic enzymes activities, hepatic hydroxyproline content and histopathological changes particularly increased collagen fibre deposition around the portal tract. In addition, there was inflammation (as reflected in increase in interleukin-1beta 'IL-1β', decrease in interleukin-10 'IL-10' serum levels and increase in IL-1β/IL-10 ratio), oxidative stress (as reflected in increase in malondialdehyde (MDA) level, reduction in reduced glutathione (GSH) content and inhibition of catalase (CAT) activity) and apoptosis [as reflected in an increase in caspase-3 level and a decrease in numbers of B-cell lymphoma 2 (BCL2)-immunopositive hepatocytes]. Interestingly, BPA had an upregulating effect on an extracellular matrix turnover gene [as reflected in matrix metalloproteinase-9 (MMP-9)] and a downregulating effect on its inhibitor gene [as reflected in tissue inhibitor of matrix metalloproteinase-2 (TIMP-2)] expression. Thus, the mechanism by which BPA induced liver fibrosis seems to be related to stimulation of the inflammatory response, along with oxidative stress, the apoptotic pathway and activation of extracellular matrix turnover.

Induction Effect of Bisphenol A on Gene Expression Involving Hepatic Oxidative Stress in Rat

Background and Objective. Bisphenol A (BPA) is an abundantly used xenoestrogenic chemical which may cause various disorders in body. In the present study, we sought to investigate the effects of various doses of BPA on hepatic oxidative stress-related gene expression in rats. Methods. Male Wistar rats weighing 150–200 g were used in this study. Three doses of the BPA (5, 25, and 125 μg/kg) in corn oil were administered as gavage during 35 consecutive days. After the experiment, the rats were expired and the livers were removed and stored at −80°C freezer for RNA extraction. Findings. The Real Time PCR showed increased expression of HO-1 in the rats receiving BPA doses compared to the control group. This effect was dose-dependent and higher at doses of 25 and 125 μg/kg than 5 μg/kg of body weight (p < 0.05). It was also demonstrated that various doses BPA can increase GADD45B gene expression compared to control group. That expression was significantly dominant in the lowest dose (5 μg/kg) of the BPA (p < 0.05). The final body weights (168.0 ± 10.0 gr) in the treatment group [BPA (125 μg/kg)] showed a significant decrease compared to control group (191.60 ± 6.50 gr). Conclusion. These findings demonstrate that BPA generated ROS and increased the antioxidant gene expression that causes hepatotoxicity.