ERα-agonist and ERβ-antagonist bifunctional next-generation bisphenols with no halogens: BPAP, BPB, and BPZ

Genotoxicity of bisphenol AF in rats: Detrimental to male reproductive system and probable stronger micronucleus induction potency than BPA

Bisphenol AF (BPAF), as one of structural analogs of BPA, has been increasingly used in recent years. However, limited studies have suggested its adverse effects similar to or higher than BPA. In order to explore the general toxicity and genotoxicity of subacute exposure to BPAF, the novel 28-day multi-endpoint (Pig-a assay + micronucleus [MN] test + comet assay) genotoxicity evaluation platform was applied. Male rats were randomly distributed into seven main experimental groups and four satellite groups. The main experimental groups included BPAF-treated groups (0.5, 5, and 50 μg/kg·bw/d), BPA group (10 μg/kg·bw/d), two solvent control groups (PBS and 0.1% ethanol/99.9% oil), and one positive control group (N-ethyl-N-nitrosourea, 40 mg/kg bw). The satellite groups included BPAF high-dose recovery group (BPAF-HR), oil recovery group (oil-R), ENU recovery group (ENU-R), and PBS recovery group (PBS-R). All groups received the agents orally via gavage for 28 consecutive days, and satellite groups were given a recovery period of 35 days. Among all histopathologically examined organs, testis and epididymis damage was noticed, which was further manifested as blood-testis barrier (BTB) junction protein (Connexin 43 and Occludin) destruction. BPAF can induce micronucleus production and DNA damage, but the genotoxic injury can be repaired after the recovery period. The expression of DNA repair gene OGG1 was downregulated by BPAF. To summarize, under the design of this experiment, male reproductive toxicity of BPAF was noticed, which is similar to that of BPA, but its ability to induce micronucleus production may be stronger than that of BPA.

Mixture Effects of Bisphenol A and Its Structural Analogs on Estrogen Receptor Transcriptional Activation

Bisphenol A (BPA) exposure has been widely linked to endocrine-disrupting effects. Recently, many substitutes for BPA have been developed as safe structural analogs. However, they have still been reported to have similar adverse effects. The current study evaluated the effects of bisphenol A and eight structural analogs on the transcription of estrogen receptor alpha (ERα). The effects of binary and ternary mixtures prepared from different combinations of BPA analogs were also evaluated for transcription activity. The measured data of the mixtures were compared to the predicted data obtained by the full logistic model, and the model deviation ratio (MDR) was calculated to determine whether the effects were synergistic, antagonistic, or additive. Overall, the results suggest that the effect of bisphenol compound are additive in binary and ternary mixtures.

Structural and energetic basis of interaction between human estrogen-related receptor γ and environmental endocrine disruptors from multiple molecular dynamics simulations and free energy predictions

Environmental endocrine disruptors (EEDs), a class of molecules that are widespread in our environment, may adversely affect the endocrine system. Exploring the interactions between these compounds and their potential targets is important for assessing their role in the organism. Focused on the human estrogen-related receptor γ (hERRγ) with BPA, BPB, HPTE, BPE, BP(2,2)(Et), and BP(2,2)(MeO) complexes, respectively, we groped for the mechanisms of conformational changes and interactions of hERRγ when binding to these six EEDs by combining multiple molecular dynamics (MD) simulations with energy prediction (MM-PBSA and solvated interaction energy (SIE)). Dynamics analysis results revealed these six EEDs have different effects on the internal dynamics of hERRγ, resulting in significant changes in the interaction of key residues around Leu268, Val313, Leu345, and Phe435 with EEDs, and thus affected its binding energy with these EEDs. The energy calculations further demonstrated that van der Waals interactions are critical for these EEDs binding to hERRγ. These results present detailed molecular insight into the interaction features between EEDs and hERRγ and help guide the search for safer alternatives to BPA.

Effect of bromelain on sperm quality, testicular oxidative stress and expression of oestrogen receptors in bisphenol-A treated male mice

Bisphenol A (BPA) as an endocrine-disrupting chemical (EDC) with low estrogenic activity increases oxidative stress and testicular damage. Bromelain is a mixture of different thiol endopeptidases and other components with many uses as a natural anti-inflammatory enzyme. The present study aimed to evaluate the effect of bromelain on male reproductive failure induced by BPA. A total of 60 healthy adult male mice were randomly divided into six groups (n = 6), including control, bromelain (70 mg/kg), BPA (5 and 600 mg/kg), and BPA (5 and 600 mg/kg) + bromelain. BPA and bromelain were administrated orally for 35 days. Then, the epididymis and testes were removed to evaluate sperm parameters, oxidative stress markers, serum levels of testosterone concentrations, and oestrogen receptors expression. The BPA significantly (P < 0.05) decreased sperm count, motility, viability, and normal sperm morphology, as well as testosterone levels, oestrogen receptors alpha (ERα) and beta (ERβ), GPx, CAT, and SOD activity than control. Also, BPA significantly (P < 0.05) increased the sperm anomalies, and MDA concentration. Co-administration of bromelain + BPA caused a significantly (P < 0.05) increase sperm count, normal sperm morphology, testosterone levels, expression of ERα and ERβ, and GPx, CAT, and SOD activity than the BPA group (P < 0.05). Also, Bromelain significantly (P < 0.05) decreased sperm anomalies and MDA concentration than control. Based on the results of this study, it appears that BPA causes side effects on male reproduction. While, bromelain has the potential to reduce the side effects of BPA on the male reproductive system.