The roles of membrane permeability and efflux pumps in the toxicity of bisphenol S analogues (2,4-bisphenol S and bis-(3-allyl-4-hydroxyphenyl) sulfone) to Escherichia coli K12.

Bisphenol S (BPS) analogues are a group of recently reported emerging contaminants in the environment. Bacteria are important components of food webs. However, the potential risks of BPS analogues in bacteria have not been fully addressed. The toxicity effects and related mechanisms of two BPS analogues with different molecular weights (2,4-bisphenol S (2,4-BPS) and bis-(3-allyl-4-hydroxyphenyl) sulfone (TGSA)) on Escherichia coli K12 were compared. The minimum inhibitory concentration (MIC) of 2,4-BPS in the wild-type of E. coli K12 was lower than that of TGSA. The membrane permeability of the wild-type increased significantly after exposed to the same concentrations (0.5-50 nmol L-1) of 2,4-BPS and TGSA. In addition, 2,4-BPS induced more significant changes in membrane permeability than TGSA. Hormetic effects of 2,4-BPS and TGSA in the wild-type strain were noted in the levels of outer membrane proteins (ompC and ompF), multidrug efflux pump acriflavine resistance B (acrB) and type II topoisomerases. Transcriptomic results indicated these two BPS analogues inhibited the function of ABC transporters. In contrast to TGSA, 2,4-BPS affected DNA replication, tricarboxylic acid cycle, oxidative phosphorylation, and inhibited energy metabolism. Compared with wild-type strain, the ΔacrB mutant strain showed enhanced susceptibility to 2,4-BPS and TGSA with their MICs reduced by 20% and 11%, respectively. Deletion of the acrB affected the growth characteristics and induced stronger oxidative stress than the wild-type strain when exposed to 2,4-BPS or TGSA. The results suggested that 2,4-BPS were more toxic to E. coli K12 than TGSA in the concentration range of 0.5-50 nmol L-1, which was supported by the evidence from their impacts on membrane permeability and efflux pumps.

Thyroid endocrine disruption and hepatotoxicity induced by bisphenol AF: Integrated zebrafish embryotoxicity test and deep learning.

Bisphenol AF (BPAF) is an emerging contaminant prevalent in the environment as one of main substitutes of bisphenol A (BPA). It was found that BPAF exhibited estrogenic effects in zebrafish larvae in our previous study, while little is known about its effects on the thyroid and liver. A 7 d zebrafish embryotoxicity test was conducted to study the potential thyroid disruption and hepatotoxicity of BPAF. BPAF decreased levels of thyroid hormones and deiodinases but increased expressions of transthyretin at 12.5 and 125 µg/L after 7 d exposure, indicating that both the metabolism and transport of thyroid hormones were perturbed. The thyroid hormone receptor (TR) levels decreased significantly upon exposure to ≥12.5 µg/L BPAF, implying that BPAF acts as a TR antagonist, which coincided well with the prediction from the Direct Message Passing Neural Network. The liver impairment (mainly cell necrosis of hepatocytes) and apoptosis were triggered by 125 µg/L and ≥12.5 µg/L BPAF respectively, accompanied by the increased activities of caspase 3 and caspase 9. Thus BPAF might not be a safe alternative to BPA given the thyroid and liver toxicity. DMPNN appears useful to screen for thyroid disrupting activity from molecular structures.

Egg Yolk Phosphatidylethanolamine: Extraction Optimization, Antioxidative Activity, and Molecular Structure Profiling.

Although phosphatidylethanolamine (PE) is an important functional phospholipid, there have been very few reports on its antioxidant activity and corresponding molecular composition. Crude PE was extracted from egg yolk with various solvents, and response surface modeling was carried out to determine the optimum extraction conditions for PE, under which the PE content in extracts reached 58.94 µg/mL. The crude PE was purified using silica gel-based column chromatography. High-purity PE (98%), identified by high-performance liquid chromatography-evaporative light-scattering detector, was obtained using isocratic elution with a mixed solvent (chloroform: methanol: acetic acid = 18:5:1) eluent. PE purified from egg yolk exhibited high radical-scavenging activity, determined by electron paramagnetic resonance (EPR). The result was attributed to the high unsaturated fatty acids (83.10%) content in egg yolk PE, and the unsaturated fatty acids were identified as PE-16:0/18:1Δ 9 , PE-16:0/18:2Δ 9,12 , PE-16:0/20:4Δ 5,8,11,14 , PE-18:0/18:1Δ 9 , PE-18:0/18:2Δ 9,12 , and PE-18:0/20:4Δ 5,8,11,14 by MALDI-TOF MS combined with gas chromatography mass spectrometry. PRACTICAL APPLICATION: In this work, an attempt has been made to explore the antioxidant activity of PE that extracted and purified from egg yolk and its corresponding molecular composition. Owing to its plentiful unsaturated fatty acids (83.10%), purified PE from egg yolk exhibited a high radical-scavenging activity that indicated that egg-yolk PE had a strong antioxidant activity, and it might exert possible beneficial effects on the human health.