Comparative evaluation of the effects of bisphenol derivatives on oxidative stress parameters in HepG2 cells

Comparative in silico and in vitro evaluation of possible toxic effects of bisphenol derivatives in HepG2 cells

Introduction

Bisphenols are widely used in the production of polycarbonate plastics and resin coatings. Bisphenol A (BPA) is suggested to cause a wide range of unwanted effects and "low dose toxicity". With the search for alternative substances to BPA, the use of other bisphenol derivatives namely bisphenol F (BPF) and bisphenol S (BPS) has increased.

Methods

In the current study, we aimed to evaluate the in silico predicted inhibitory concentration 50s (pIC50s) of bisphenol derivatives on immune and apoptotic markers and DNA damage on HepG2 cells. Moreover, apoptotic, genotoxic and immunotoxic effects of BPA, BPF and BPS were determined comparatively. Effects of bisphenols on apoptosis were evaluated by detecting different caspase activities. The genotoxic effects of bisphenols were evaluated by measuring the levels of 8-hydroxy-2'-deoxyguanosine (8-OHdG) and 8-oxoguanine glycosylase (OGG1). To determine the immunotoxic effect of bisphenol derivatives, the levels of interleukin 4 (IL-4) and interleukin 10 (IL-10), transforming growth factor beta (TGF-β) and tumor necrosis factor-alpha (TNF-α), which are known to be expressed by HepG2 cells, were measured. Results: In silico data indicate that all of the bisphenols may cause alterations in immune and apoptotic markers as well as DNA damage at low doses. İn vitro data revealed that all bisphenol derivatives could affect immune markers at inhibitory concentration 30s (IC30s). In addition, BPF and BPS may also have apoptotic immunotoxic effects.

Conclusion

Both in silico and in vivo research are needed further to examine the toxic effects of alternative bisphenol derivatives.

Bisphenol derivatives in cord blood and association between thyroid hormones and potential exposure sources

Endocrine-disrupting environmental chemicals are a public health concern, particularly fetal exposure to Bisphenol derivatives. This study aimed to assess fetal exposure to Bisphenol derivatives (BPA, BPF, and BPS) by measuring their levels in cord blood and investigating their association with plastic material used in daily life as well as cord blood TSH and free L-thyroxine (fT4) levels. In this descriptive study, a questionnaire with a face-to-face interview was administered before birth, and cord blood samples were taken immediately after delivery. The mean levels of BPA, BPF, TSH, and fT4 were measured as 10.69 ± 2.39 ng/ml, 3.80 ± 0.58 ng/ml; 2.36 ± 0.23 µIU/ml, and 14.18 ± 0.53 pg/ml, respectively, in a total of 104 cord blood samples. All BPS levels remained below the detection limit. Linear regression analysis revealed a positive association between birth weight and cord blood BPA concentration (β = 0.26; p = 0.02). Further research on maternal exposure during the fetal and neonatal period is critical for public health.

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.

Adverse (geno)toxic effects of bisphenol A and its analogues in hepatic 3D cell model

Bisphenol A (BPA) is one of the most widely used and versatile chemical compounds in polymer additives and epoxy resins for manufacturing a range of products for human applications. It is known as endocrine disruptor, however, there is growing evidence that it is genotoxic. Because of its adverse effects, the European Union has restricted its use to protect human health and the environment. As a result, the industry has begun developing BPA analogues, but there are not yet sufficient toxicity data to claim that they are safe. We investigated the adverse toxic effects of BPA and its analogues (BPS, BPAP, BPAF, BPFL, and BPC) with emphasis on their cytotoxic and genotoxic activities after short (24-h) and prolonged (96-h) exposure in in vitro hepatic three-dimensional cell model developed from HepG2 cells. The results showed that BPFL and BPC (formed by an additional ring system) were the most cytotoxic analogues that affected cell viability, spheroid surface area and morphology, cell proliferation, and apoptotic cell death. BPA, BPAP, and BPAF induced DNA double-strand break formation (γH2AX assay), whereas BPAF and BPC increased the percentage of p-H3-positive cells, indicating their aneugenic activity. All BPs induced DNA single-strand break formation (comet assay), with BPAP (≥0.1 μM) being the most effective and BPA and BPC the least effective (≥1 μM) under conditions applied. The results indicate that not all of the analogues studied are safer alternatives to BPA and thus more in-depth research is urgently needed to adequately evaluate the risks of BPA analogues and assess their safety for humans.

Relationship between emergent BPA-substitutes and renal and cardiovascular diseases in adult population

Plastic waste pollution is one of the leading environmental problems of modern society. Its use, disposal, and recycling lead to the release of xenobiotic compounds such as bisphenol A (BPA), a known endocrine disruptor related to numerous pathologies. Due to the new restrictions on its use, it is gradually being replaced by derived molecules, such as bisphenol F or S (BPF or BPS), whose health risks have not yet been adequately studied. In the present work, significant relationships between the new BPA substitute molecules and renal and cardiovascular diseases have been detected by performing binomial and multinomial logistic regressions in one of the world's largest cohorts of urinary phenols. The results have shown a significant relationship between urinary BPF and renal function or heart disease (specifically congestive heart failure). Urinary BPS has shown a positive relationship with the risk of hypertension and a negative relationship with kidney disease. Consequently, applying new substitute molecules could imply potential health risks equivalent to BPA.