Inhibited Nitric Oxide Production of Human Endothelial Nitric Oxide Synthase by Nitrated and Oxygenated Polycyclic Aromatic Hydrocarbons

Deconvoluting nitric oxide-protein interactions with spatially resolved multiplex imaging

Simultaneous imaging of nitric oxide (NO) and its proximal proteins should facilitate the deconvolution of NO-protein interactions. While immunostaining is a primary assay to localize proteins in non-genetically manipulated samples, NO imaging probes with immunostaining-compatible signals remain unexplored. Herein, probe NOP-1 was developed with an NO-triggered proximal protein labeling capacity and fluorogenic signals. The trick is to fuse the native chemical ligation of acyl benzotriazole with the protein-conjugation-induced fluorogenic response of Si-rhodamine fluorophore. NOP-1 predominantly existed in the non-fluorescent spirocyclic form. Yet, its acyl o-phenylenediamine moiety was readily activated by NO into acyl benzotriazole to conjugate proximal proteins, providing a fluorogenic response and translating the transient cellular NO signal into a permanent stain compatible with immunostaining. NOP-1 was utilized to investigate NO signaling in hypoglycemia-induced neurological injury, providing direct evidence of NO-induced apoptosis during hypoglycemia. Mechanistically, multiplex imaging revealed the overlap of cellular NOP-1 fluorescence with immunofluorescence for α-tubulin and NO2-Tyr. Importantly, α-tubulin was resolved from NOP-1 labeled proteins. These results suggest that NO played a role in hypoglycemia-induced apoptosis, at least in part, through nitrating α-tubulin. This study fills a crucial gap in current imaging probes, providing a valuable tool for unraveling the complexities of NO signaling in biological processes.

Characteristics of typical intermediate and semi volatile organic compounds in Shanghai during China International Import Expo event

To ensure good air quality during the China International Import Expo (CIIE) event, stringent emission-reduction measures were implemented in Shanghai. To assess the efficacy of these measures, this study measured typical categories of intermediate/semi volatile organic compounds (I/SVOCs), including alkanes (C10-C26 n-alkanes and pristane), EPA-priority polycyclic aromatic hydrocarbons (PAHs), alkylnaphthalenes, benzothiazole (BTH) and chlorobenzenes (CBs), at an urban site of Shanghai before and during two CIIE events (2019 and 2020; non-CIIE versus CIIE). The average concentrations of alkanes and PAHs during both 2019 and 2020 CIIE events decreased by approximately 41% and 17%, respectively, compared to non-CIIE periods. However, the decline in BTH and CBs was only observed during CIIE-2019. Secondary organic aerosol (SOA) formation from alkanes, PAHs and BTH was evaluated under atmospheric conditions, revealing considerable SOA contributions from dimethylnaphthalenes and BTH. Positive matrix factorization (PMF) analysis further revealed that life-related sources, such as cooking and residential emissions, make a noticeable contribution (21.6%) in addition to the commonly concerned gasoline-vehicle sources (31.5%), diesel-related emissions (20.8%), industrial emissions (18.6%) and ship emissions (7.5%). These findings provide valuable insights into the efficacy of the implemented measures in reducing atmospheric I/SVOCs levels. Moreover, our results highlight the significance of exploring additional individual species of I/SVOCs and life-related sources for further research and policy development.

Environmental dose of 16 priority-controlled PAHs induce endothelial dysfunction: An in vivo and in vitro study

Polycyclic aromatic hydrocarbons (PAHs) exposure is related to the occurrence of cardiovascular diseases (CVDs). Endothelial dysfunction is considered an initial event of CVDs. To confirm the relationship of PAHs exposure with endothelial dysfunction, 8-week-old male SD rats and primary human umbilical vein endothelial cells (HUVECs) were co-treated with environmental doses of 16 priority-controlled PAHs for 90 d and 48 h, respectively. Results showed that 10× PAHs exposure remarkably raised tumor necrosis factor-α and malonaldehyde levels in rat serum (p < 0.05), but had no effects on interleukin-8 levels and superoxide dismutase activity. The expressions of SIRT1 in HUVECs and rat aorta were attenuated after PAHs treatment. Interestingly, PAHs exposure did not activate the expression of total endothelial nitric oxide synthase (eNOS), but 10× PAHs exposure significantly elevated the expression of phosphorylated eNOS (Ser1177) in HUVECs and repressed it in aortas, accompanied with raised nitrite level both in serum and HUVECs by 48.50-253.70 %. PAHs exposure also led to the augment of endothelin-1 (ET-1) levels by 19.76-38.54 %, angiotensin (Ang II) levels by 20.09-39.69 % in HUVECs, but had no effects on ET-1 and Ang II levels in serum. Additionally, PAHs exposure improved endocan levels both in HUVECs and serum by 305.05-620.48 % and stimulated the THP-1 cells adhered to HUVECs (p < 0.05). After PAHs treatment, the smooth muscle alignment was disordered and the vascular smooth muscle locally proliferated in rat aorta. Notably, the systolic blood pressure of rats exposed to 10× PAHs increased significantly compared with the control ones (131.28 ± 5.20 vs 116.75 ± 5.33 mmHg). In summary, environmental chronic PAHs exposure may result in endothelial dysfunction in SD rats and primary HUVECs. Our research can confirm the cardiovascular damage caused by chronic exposure to PAHs and provide ideas for the prevention or intervention of CVDs affected by environmental factors.

Bisphenols and brominated bisphenols induced endothelial dysfunction via its disruption of endothelial nitric oxide synthase

Emerging literatures have concentrated on the association between cardiovascular diseases risk of typical endocrine disruptor bisphenols, which also put forward the further studies need respect to the potential mechanism. Herein, we investigated the endothelial dysfunction effects of bisphenols and brominated bisphenols involved in aortic pathological structure, endothelial nitric oxide synthase (eNOS) protein phosphorylation, synthase activity and nitric oxide (NO) production in human umbilical vein endothelial cells (HUVECs) and C57BL/6 mice. Bisphenol A (BPA) and bisphenol S (BPS) increased NO production by 85.7% and 68.8% at 10-6 M level in vitro and 74.3%, 41.5% in vivo, respectively, while tetrabromobisphenol S (TBBPS) significantly inhibited NO by 55.7% at 10-6 M in vitro and 28.9% in vivo at dose of 20 mg/kg BW/d. Aortic transcriptome profiling revealed that the process of 'regulation of NO mediated signal transduction' was commonly induced. The mRNA and protein expression of phosphorylated eNOS at Ser1177 were promoted by BPA and BPS but decreased by TBBPA and TBBPS in HUVECs. Phosphorylation and enzymatic activity of eNOS were significantly increased by 43.4% and 13.8% with the treatment of BPA and BPS at 10-7 M, but decreased by 16.9% after exposure to TBBPS at 10-6 M in vitro. Moreover, only TBBPS was observed to increase aorta thickness significantly in mice and induce endothelial dysfunction. Our work suggests that bisphenols and brominated bisphenols may exert adverse outcome on vascular health differently in vitro and in vivo, and emphasizes areas of public health concern similar endocrine disruptors vulnerable on the vascular endothelial function.

The occurrence and sources of PAHs, oxygenated PAHs (OPAHs), and nitrated PAHs (NPAHs) in soil and vegetation from the Antarctic, Arctic, and Tibetan Plateau

Although the fate of PAHs in the three polar regions (Antarctic, Arctic, and Tibetan Plateau) has been investigated, the occurrence and contamination profiles of PAH derivatives such as oxygenated PAHs (OPAHs) and nitrated PAHs (NPAHs) remain unclear. Some of them are more toxic and can be transformed from PAHs in environment. This study explored and compared the concentrations composition profiles and potential sources of PAHs, OPAHs, and NPAHs in soil and vegetation samples from the three polar regions. The total PAH, OPAH, and NPAH concentrations were 3.55-519, n.d.-101, and n.d.-1.10 ng/g dry weight (dw), respectively. The compounds were dominated by three-ring PAHs, and the most abundant individual PAH and OPAH were phenanthrene (PHE) and 9-fluorenone (9-FO), respectively. The sources of PAHs and their derivatives were qualitatively analyzed by the diagnostic ratios and quantified using the positive matrix factorization (PMF) model. The ratios of PAH derivatives to parent PAHs (9-FO/fluorene and 9,10-anthraquinone/anthracene) were significantly higher in the Antarctic samples than in the Arctic and TP samples, implying a higher occurrence of secondary OPAH and NPAH formation in the Antarctic region. To our knowledge, this is the first comparative study that simultaneously investigated the contamination profiles of PAHs and their derivatives in the three polar regions. The findings of this study provide a scientific basis for the development of risk assessment and pollution control strategies in these fragile regions.

Selective cascade activation of polycyclic aromatic hydrocarbons in human cells: Role of enzyme's intrinsic electric field

Polycyclic aromatic hydrocarbons (PAHs) are major environmental organic pollutants. Some metabolites of PAHs show greater toxicity to humans while the others do not. It is highly important to decipher PAHs' regioselective activation mechanism and identify the major metabolites to accurately evaluate their public health risk. Here, we have performed a thorough computational study of benzo[a]anthracene (BA) metabolized by P450 1A1 by employing molecular docking, molecular dynamics simulations, quantum chemical calculation, and quantum mechanics/molecular mechanics calculations. Our findings show that highly-reactive species such as 3,4-epoxide, 8,9-epoxide, 3,4-diol-1,2-epoxide, and 8,9-diol-10,11-epoxide were major metabolites, which can efficiently react with guanine and damage DNA with extremely low energy barrier, therefore, supports the regioselective metabolism of BA. The origin of this selective activation is mainly contributed to both the oxygen‑carbon distance and previously overlooked enzyme's intrinsic electric field. Consequently, based on the resolved activation selectivity of BA. We built a high-throughput strategy to efficiently predict the metabolites of other PAHs. The accuracy of the strategy is validated by studying 16 PAHs on the priority control list. Hopefully this will aid the accurate evaluation of public health risks associated with PAH emissions.

Nitro substituent caused negative impact on occurrence and development of atherosclerotic plaque by PM2.5-bound polycyclic aromatic compounds

PM2.5 exposure is a significant risk factor for the occurrence and development of atherosclerosis. Polycyclic aromatic hydrocarbons (PAHs) play prominent roles in PM2.5-related toxicity. However, the nitrated derivatives of PAHs, nitrated polycyclic aromatic hydrocarbons (NPAHs), have strong oxidizing properties due to the nitro substituents. Thus, the in vivo and in vitro experiments exposure to benzo[a]pyrene (BaP) and 6-nitro benzo[a]pyrene (NBaP) were conducted to evaluate the effect of nitro substituent on the atherosclerosis due to (or attributable to) PAHs. The results showed that NBaP exposure induced the inhibition of human umbilical vein endothelial cells (HUVECs) viability and cell morphology damage via more severe oxidative stress than BaP exposure. Furthermore, exposure to PM2.5-bound NBaP caused dyslipidemia in the Apolipoprotein E-deficient (ApoE-/-) mice, including the increment of total cholesterol, triglycerides, low-density lipoprotein cholesterol, and malondialdehyde levels, and the decrement of high-density lipoprotein cholesterol levels, superoxide dismutase and glutathione peroxidase levels in serum and aorta. Furthermore, histology showed atherosclerotic plaque in the aorta of ApoE-/- mice. However, there were no significant differences of the physiological and pathological changes between BaP and control groups. Thus, NPAHs induced endothelial dysfunction and dyslipidemia via severe oxidative stress, and further accelerated the occurrence and development of atherosclerosis compared with the parent PAHs. Our findings provide the first evidence that nitro substituent caused much severer negative health impact of polycyclic aromatic compounds, which highlight the significance of NPAHs in health risk estimation of polycyclic aromatic compounds.

Insights into human eNOS, nNOS and iNOS structures and medicinal indications from statistical analyses of their interactions with bound compounds

83 Structures of human nNOS, 55 structures of human eNOS, 13 structures of iNOS, and about 126 reported NOS-bound compounds are summarized and analyzed. Structural and statistical analysis show that, at least one copy of each analyzed compound binds to the active site (the substrate arginine binding site) of human NOS. And binding features of the three isoforms show differences, but the binding preference of compounds is not in the way helpful for inhibitor design targeting nNOS and iNOS, or for activator design targeting eNOS. This research shows that there is a strong structural and functional similarity between oxygenase domains of human NOS isoforms, especially the architecture, residue composition, size, shape, and distribution profile of hydrophobicity, polarity and charge of the active site. The selectivity and efficacy of inhibitors over the rest of isoforms rely a lot on chance and randomness. Further increase of selectivity via rational improvement is uncertain, unpredictable and unreliable, therefore, to achieve high selectivity through targeting this site is complicated and requires combinative investigation. After analysis on the current two targeting sites in NOS, the highly conserved arginine binding pocket and H4B binding pocket, new potential drug-targeting sites are proposed based on structure and sequence profiling. This comprehensive analysis on the structure and interaction profiles of human NOS and bound compounds provides fresh insights for drug discovery and pharmacological research, and the new discovery here is practically applied to guide protein-structure based drug discovery.

Urinary polycyclic aromatic hydrocarbon metabolites were associated with short sleep duration and self-reported trouble sleeping in US adults: data from NHANES 2005-2016 study population

Background

The aim of the current study was to investigate the link between human exposure to PAHs with short sleep duration (SSD) and self-reported trouble sleeping.

Methods

A total of 9,754 participants and 9,777 participants obtained from NHANES 2005-2016 were included in this cross-sectional study about SSD and self-reported trouble sleeping, respectively. The association between urinary PAHs metabolites with the prevalence of SSD and self-reported trouble sleeping by the weighted multivariate logistic regression model, restricted cubic spline (RCS) curves, and weighted quantile sum (WQS) regression.

Results

After adjusting for all covariates, 1-hydroxynapthalene, 2-hydroxynapthalene, 3-hydroxyfluorene, 2-hydroxyfluorene, 1-hydroxyphenanthrene, and 1-hydroxyphenanthrene demonstrated positive associations with SSD prevalence. Besides, 1-hydroxynapthalene, 2-hydroxynapthalene, 3-hydroxyfluorene, 2-hydroxyfluorene, 1-hydroxyphenanthrene, and 1-hydroxyphenanthrene exhibited positive associations with the prevalence of self-reported trouble sleeping following the adjustment for all covariates. RCS curves confirmed the non-linear associations between 1-hydroxynapthalene, 2-hydroxynapthalene, 3-hydroxyfluorene, 2-hydroxyfluorene, and 1-hydroxyphenanthrene with the prevalence of SSD, and 1-hydroxynapthalene, 3-hydroxyfluorene, and 2-hydroxyfluorene with the prevalence of self-reported trouble sleeping. The WQS results showed that mixed exposure to PAH metabolites had a significant positive association with the prevalence of SSD (OR: 1.087, 95% CI: 1.026, 1.152, p = 0.004) and self-reported trouble sleeping (OR: 1.190, 95% CI: 1.108, 1.278, p < 0.001).

Conclusion

Urinary concentrations of PAH metabolites exhibited a close association with the prevalence of SSD and self-reported trouble sleeping in US adults. More emphasis should be placed on the importance of environmental effects on sleep health.

Regioselective oxidation of heterocyclic aromatic hydrocarbons catalyzed by cytochrome P450: A case study of carbazole

Recently there are increasing interests in accurately evaluating the health effects of heterocyclic PAHs. However, the activation mechanism and possible metabolites of heterocyclic PAHs catalyzed by human CYP1A1 is still elusive to a great extent. Here, leveraged to high level QM/MM calculations, the corresponding activation pathways of a representative heterocyclic PAHs, carbazole, were systematically explored. The first stage is electrophilic addition or hydrogen abstraction from N-H group. Electrophilic addition was evidenced to be more feasible and regioselectivity at C3 and C4 sites were identified. Correlations between energy barriers and key structural/electrostatic parameters reveal that O-Cα distance and Fe-O-Cα angle are the main origin for the catalytic regioselectivity. Electrophilic addition was determined as the rate-determining step and the subsequent possible reactions include epoxidation, NIH shift (the hydrogen migration from the site of hydroxylation to the adjacent carbon) and proton shuttle. The corresponding products are epoxides, ketones and hydroxylated carbazoles, respectively. The main metabolites (hydroxylated carbazoles) are estimated to be more toxic than carbazole. The regioselectivity of carbazole activated by CYP1A1 is different from the environmental processes (gas and aqueous phase). Collectively, these results will inform the in-depth understanding the metabolic processes of heterocyclic PAHs and aid the accurate evaluation of their health effects.

Oxygenated polycyclic aromatic hydrocarbons in food: toxicity, occurrence and potential sources

Oxygenated polycyclic aromatic hydrocarbons (OPAHs) are polycyclic aromatic hydrocarbons (PAHs) functionalized with at least one carbonyl group and are generally thought to be more toxic than PAHs. In this review, the physical-chemical properties, toxicity, occurrence, and potential sources of OPAHs in food were comprehensively discussed. The toxicities of 1,2-naphthoquinone, 1,4-naphthoquinone, 6H-benzo[cd]pyren-6-one, benzo[a]anthracene-7,12-quinone and 9,10-phenanthrenequinone were prominent among the OPAHs. Both 1,4-naphthoquinone and 1,2-naphthoquinone exhibited strong genotoxicity, cytotoxicity, and developmental toxicity. 6H-benzo[cd]pyren-6-one and benzo[a]anthracene-7,12-quinone showed high genotoxicity and cardiovascular toxicity. Although 9,10-phenanthrenequinone showed no genotoxicity, it exhibited almost the strongest cytotoxicity. For the majority of foods, the concentrations of OPAHs and PAHs were on the same order of magnitude. OPAHs tend to be positively correlated with the corresponding PAH concentrations in oil and fried food, while for barbequed food and seafood, no obvious correlation was found. In addition, 9-fluorenone, 9,10-anthraquinone, benzanthrone and 1,2-acenaphthenequinone had high abundance in food. Environmental pollution, food composition, storage conditions, heating methods, and other treatments influence the accumulation of OPAHs in food. Furthermore, oxygen and water played an important role in the transformation from PAHs to OPAHs. In short, this review guides the evaluation and further reduction of OPAH-related health risks in food.

Effect of fungal indoor air pollutant 1-octen-3-ol on levels of reactive oxygen species and nitric oxide as well as dehydrogenases activities in drosophila melanogaster males

Fungal pollution of indoor environments contributes to several allergic symptoms and represents a public health problem. It is well-established that 1-octen-3-ol, also known as mushroom alcohol, is a fungal volatile organic compound (VOC) commonly found in damp indoor spaces and responsible for the typical musty odor. Previously it was reported that exposure to 1-octen-3-ol induced inflammations and disrupted mitochondrial morphology and bioenergetic rate in Drosophila melanogaster. The aim of this study was to examine the influence of 1-octen-3-ol on dehydrogenase activity, apoptotic biomarkers, levels of nitric oxide (NO) and reactive oxygen species (ROS), as well as antioxidant enzymes activities. D. melanogaster flies were exposed to an atmosphere containing 1-octen-3-ol (2.5 or ∞l/L) for 24 hr. Data demonstrated that 1-octen-3-ol decreased dehydrogenases activity and NO levels but increased ROS levels accompanied by stimulation of glutathione-S-transferase (GST) and superoxide dismutase (SOD) activities without altering caspase 3/7 activation. These findings indicate that adverse mitochondrial activity effects following exposure of D. melanogaster to 1-octen-3-ol, a fungal VOC, may be attributed to oxidant stress. The underlying mechanisms involved in adverse consequences of indoor fungal exposure appear to be related to necrotic but not apoptotic mechanisms. The adverse consequences were sex-dependent with males displaying higher sensitivity to 1-octen-3-ol. Based upon on the fact that the fly genome shares nearly 75% of disease-related genes to human exposure to this fungus may explain the adverse human responses to mold especially for males.

Adsorption mechanism of polycyclic aromatic hydrocarbons using wood waste-derived biochar

The polycyclic aromatic hydrocarbons (PAHs) have been attracted increasing attentions due to their carcinogenicity and teratogenicity. Adsorption is widely considered one of the most potential technologies for PAHs removal. In this study, we prepared two kinds of oxygen-rich biochar derived from waste wood to investigate the PAHs adsorption performance, and the molecular simulation was used to build the 16 priority PAHs, 23 nitrated PAHs, 9 oxygenated PAHs adsorption model. The surface adsorption performance of oxygen-rich biochar significantly depends on the pyrolysis conditions. The main out-comings demonstrated that the adsorption of naphthalene (C₁₀H₈) molecules first occurred, and the optimal adsorption positions of oxygen-rich biochar strongly adhered to functional groups of carboxyl and hydroxyl. Moreover, benzene ring, -COOH, and -CH₃ of biochar were the main adsorbed functional groups for PAHs adsorption. The oxygen-rich biochar had the targeted-adsorption effect on PAHs removal especially symmetrical PAHs, and the targeted-adsorption mechanism was finally proposed. The research is beneficial to guide the removal of PAHs from polluted water and mitigate the environmental pollution caused by biomass waste mismanagement, simultaneously.

Computational biotransformation of polyethylene terephthalate by depolymerase: A QM/MM approach

Despite increasing environmental concerns on ever-lasting Polyethylene Terephthalate (PET), its global production is continuously growing. Effective strategies that can completely remove PET from environment are urgently desired. Here biotransformation processes of PET by one of the most effective enzymes, leaf-branch compost cutinase (LCC), were systematically explored with Molecular Dynamics and Quantum Mechanics/Molecular Mechanics approaches. We found that four concerted steps are required to complete the whole catalytic cycle. The last concerted step, deacylation, was determined as the rate-determining step with Boltzmann-weighted average barrier of 13.6 kcal/mol and arithmetic average of 16.1 ± 2.9 kcal/mol. Interestingly, unprecedented fluctuations of hydrogen bond length during LCC catalyzed transformation process toward PET were found. This fluctuation was also observed in enzyme IsPETase, indicating that it may widely exist in other catalytic triad (Ser-His-Asp) containing enzymes as well. In addition, possible features (bond, angle, dihedral angle and charge) that influence the catalytic reaction were identified and correlations between activation energies and key features were established. Our results present new insights into catalytic mechanism of hydrolases and shed light on the efficient recycling of the ever-lasting PET.

Carcinogenic Risk of 2,6-Di-tert-Butylphenol and Its Quinone Metabolite 2,6-DTBQ Through Their Interruption of RARβ: In Vivo, In Vitro, and In Silico Investigations

Thousands of contaminants are used worldwide and eventually released into the environment, presenting a challenge of health risk assessment. The identification of key toxic pathways and characterization of interactions with target biomacromolecules are essential for health risk assessments. The adverse outcome pathway (AOP) incorporates toxic mechanisms into health risk assessment by emphasizing the relationship among molecular initiating events (MIEs), key events (KEs), and adverse outcome (AO). Herein, we attempted the use of AOP to decipher the toxic effects of 2,6-di-tert-butylphenol (2,6-DTBP) and its para-quinone metabolite 2,6-di-tert-butyl-1,4-benzoquinone (2,6-DTBQ) based on integrated transcriptomics, molecular modeling, and cell-based assays. Through transcriptomics and quantitative real-time PCR validation, we identified retinoic acid receptor β (RARβ) as the key target biomacromolecule. The epigenetic analysis and molecular modeling revealed RARβ interference as one MIE, including DNA methylation and conformational changes. In vitro assays extended subsequent KEs, including altered protein expression of p-Erk1/2 and COX-2, and promoted cancer cell H4IIE proliferation and metastasis. These toxic effects altogether led to carcinogenic risk as the AO of 2,6-DTBP and 2,6-DTBQ, in line with chemical carcinogenesis identified from transcriptome profiling. Overall, our simplified AOP network of 2,6-DTBP and 2,6-DTBQ facilitates relevant health risk assessment.

Endothelial barrier dysfunction induced by anthracene and its nitrated or oxygenated derivatives at environmentally relevant levels

Polycyclic aromatic hydrocarbons (PAHs) are epidemiologically associated with cardiovascular diseases characterized by early key events involving in the disruption of endothelial barrier function. Whether PAHs can induce adverse cardiovascular outcome by directly destabilizing endothelial barrier function remains elusive. Herein, we investigated the effect of anthracene (ANT), 9-nitroanthracene (9-NANT), and 9,10-anthraquinone (9,10-AQ) on vascular endothelial barrier functions in human umbilical vein endothelial cells (HUVECs). The integrity of endothelial barrier in HUVECs was disturbed with a 1.15-1.42 fold increase in fluorescein leakage, and 21.8%-58.3% downregulated transendothelial electrical resistance. ANT, 9-NANT and 9,10-AQ promoted paracellular gap formation as revealed by transmission electron microscope. The disrupted cell junctions after 24 h exposure to ANT, 9-NANT and 9,10-AQ at 0.01 μM were indicated by the downregulated mRNA expression of vascular endothelial cadherin (VE-cadherin), zona occludens-1 (ZO-1) and occludin by 33.2%-71.4%, 19.1%-21.0%, and 31.9% respectively, and the downregulated protein expression of ZO-1 and occludin, and by the internalization of VE-cadherin. We demonstrated that ANT and its derivatives at environmentally relevant concentrations induced endothelial barrier dysfunction via the disruption of cell junctions, providing essential in vitro evidence on the association with their adverse cardiovascular outcomes.

Toxicity pathways of lipid metabolic disorders induced by typical replacement flame retardants via data-driven analysis, in silico and in vitro approaches

Endocrine-disrupting chemicals can interfere with hormone action via various pathways, thereby increasing the risk of adverse health outcomes. Organophosphorus ester (OPEs) retardants, a group of new emerging endocrine disruption chemicals, have been referred to as metabolism disruptors and reported to induce chronic health problems. However, the toxicity pathways were mainly focused on nuclear receptor signaling pathways. Significantly, the membrane receptor pathway (such as G protein-coupled estrogen receptor 1 (GPER) signaling pathway) had been gradually realized as the important role in respond more effective to lipid metabolism disorder than traditional nuclear receptors, whereas the detailed mechanism was unclear yet. Therefore, this study innovatively integrated the bibliometric analysis, in silico and in vitro approach to develop toxicity pathways for the mechanism interpretation. Bibliometric analysis found that the typical OPEs - triphenyl phosphate was a major concern of lipid metabolism abnormality. Results verified that TPP could damage the structures of cell membranes and exert an agonistic effect of GPER as the molecular initiating event. Then, the activated GPER could trigger the PI3K-Akt/NCOR1 and mTOR/S6K2/PPARα transduction pathways as key event 1 (KE1) and affect the process of lipid metabolism and synthesis (CPT1A, CPT2, SREBF2 and SCD) as KE2. As a result, these alterations led to lipid accumulation as adverse effect at cellular-levels. Furthermore, the potential outcomes (such as immunity damage, weight change and steatohepatitis) at high biological levels were expanded. These findings improved knowledge to deeply understand toxicity pathways of phosphorus flame retardants and then provided a theoretical basis for risk assessments.

Benzophenone-1 induced aberrant proliferation and metastasis of ovarian cancer cells via activated ERα and Wnt/β-catenin signaling pathways

Benzophenone-1 (BP-1) belongs to personal care product-related contaminants of emerging concern and has been recently reported to induce xenoestrogenic effects. However, the underlying mechanisms leading to the activation of target receptors and subsequent various adverse outcomes remain unclear, which is beneficial to safety and health risk assessment of benzophenone-type ultraviolet filters with their widespread occurrence. Herein, we investigated disrupting effects of BP-1 at environmentally relevant concentrations (10^-9-10^-6 M) on estrogen receptor (ER) α-associated signaling pathways. Molecular dynamics simulations together with yeast-based assays revealed the steady binding of BP-1 to ERα ligand binding domain (LBD) and hence the observed agonistic activity. BP-1 triggered interaction between ERα and β-catenin in human SKOV3 ovarian cancer cells and caused translocation of β-catenin from the cytoplasm to the nucleus, leading to aberrant activation of Wnt/β-catenin. BP-1 consequently induced dissemination of SKOV3 via regulating epithelial-mesenchymal transitions (EMT) biomarkers including minimally downregulating ZO-1 gene to 78.0 ± 10.1% and maximally upregulating MMP9 gene to 144.1 ± 29.7% and promoted 1.03-1.83 fold proliferation, migration and invasion of SKOV3. We provide the first evidence that the BP-1 activated ERα triggers crosstalk between ERα and Wnt/β-catenin pathway, leading to the abnormal stimulation and progression of SKOV3 cancer cells.

Characterizing the potentially neuronal acetylcholinesterase reactivity toward chiral pyraclofos: Enantioselective insights from spectroscopy, in silico docking, molecular dynamics simulation and per-residue energy decomposition studies

Chiral organophosphorus agents are distributed ubiquitously in the environment, but the neuroactivity of these asymmetric chemicals to humans remains uncertain. This scenario was to explore the stereoselective neurobiological response of human acetylcholinesterase (AChE) to chiral pyraclofos at the enantiomeric scale, and then decipher the microscopic basis of enantioselective neurotoxicity of pyraclofos enantiomers. The results indicated that (R)-/(S)-pyraclofos can form the bioconjugates with AChE with a stoichiometric ratio of 1:1, but the neuronal affinity of (R)-pyraclofos (K = 6.31 × 10⁴ M^-1) with AChE was larger than that of (S)-pyraclofos (K = 1.86 × 10⁴ M^-1), and significant enantioselectivity was existed in the biochemical reaction. The modes of neurobiological action revealed that pyraclofos enantiomers were situated at the substrate binding domain, and the strength of the overall noncovalent bonds between (S)-pyraclofos and the residues was weaker than that of (R)-pyraclofos, resulting in the high inhibitory effect of (R)-pyraclofos toward the activity of AChE. Dynamic enantioselective biointeractions illustrated that the intervention of inherent conformational flexibility in the AChE-(R)-pyraclofos was greater than that of the AChE-(S)-pyraclofos, which arises from the big spatial displacement and the conformational flip of the binding domain composed of the residues Thr-64～Asn-89, Gly-122～Asp-134, and Thr-436～Tyr-449. Energy decomposition exhibited that the Gibbs free energies of the AChE-(R)-/(S)-pyraclofos were ΔG° = －37.4/－30.2 kJ mol^-1, respectively, and the disparity comes from the electrostatic energy during the stereoselective neurochemical reactions. Quantitative conformational analysis further confirmed the atomic-scale computational chemistry conclusions, and the perturbation of (S)-pyraclofos on the AChE's ordered conformation was lower than that of (R)-pyraclofos, which is germane to the interaction energies of the crucial residues, e.g. Tyr-124, Tyr-337, Asp-74, Trp-86, and Tyr-119. Evidently, this attempt will contribute mechanistic information to uncovering the neurobiological effects of chiral organophosphates on the body.

Spatiotemporal variations and source identification of atmospheric nitrated and oxygenated polycyclic aromatic hydrocarbons in the coastal cities of the Bohai and Yellow Seas in northern China

Gaseous and particulate nitrated polycyclic aromatic hydrocarbons (NPAHs, 12 species) and oxygenated polycyclic aromatic hydrocarbons (OPAHs, 4 species) in seven coastal cities of the Bohai and Yellow Seas were determined throughout the year. The annual arithmetical mean concentrations of ΣNPAH₁₂ and ΣOPAH₄ were 737 ± 475 pg/m³ and 35.3 ± 26.8 ng/m³. NPAHs and OPAHs existed mainly in the gaseous phase, accounted for 88.5% and 95.2% of the total concentrations. Air concentrations of ΣNPAH₁₂ and ΣOPAH₄ in the coastal cities of the Yellow Sea were significantly lower (p < 0.05) than those of the Bohai Sea. Air concentrations of ΣNPAH₁₂ and ΣOPAH₄ were significantly higher (p < 0.01) in winter than in summer. Strong secondary formation of atmospheric NPAHs and OPAHs occurred in all of the studied cities. The sequence of annual contribution of the emission sources of airborne NPAHs determined by positive matrix factorization was traffic exhaust > combustion of solid fuels (coal and biomass) > secondary formation, while for OPAHs, it was combustion of solid fuels > secondary formation > traffic exhaust. The combustion of solid fuels served as the main source of NPAHs and OPAHs in winter, while secondary formation was the predominant source in summer. Interregional transport may exert an important effect on the local atmospheric NPAHs and OPAHs by potential source contribution function analysis. The estimated incremental lifetime cancer risk (ILCR) due to inhalation exposure to specific NPAHs ranged from 2.9 × 10^-12 to 6.2 × 10^-6 (median at 4.8 × 10^-9) was mainly attributed to exposure before the age of 16.

A sensitive GC-HRMS method for the simultaneous determination of parent and oxygenated polycyclic aromatic hydrocarbons in barbecued meat and meat substitutes

A sensitive GC-HRMS method was developed to analyze six polycyclic aromatic hydrocarbons (PAH; anthracene, benzo[a]anthracene, benzo[a]pyrene, benzo[b]fluoranthene, chrysene, and fluorene) and eight oxygenated PAHs (OPAH; anthracene-9,10-dione, benzo[a]anthracene-7,12-dione, 7H-benz[de]anthracene-7-one, 11H-benzo[b]fluorene-11-one, 6H-benzo[cd]pyren-6-one, 9,10-dihydro-8H-benzo[a]pyren-7-one, fluoren-9-one, and naphthacene-5,12-dione) in barbecued meat and meat substitutes. After optimization of the conditions of the sample preparation, consisting of accelerated solvent extraction (ASE) and solid-phase extraction (SPE), high recoveries (PAH 72-109%; OPAH 74-106%) were obtained. The linear regression of the matrix calibration resulted in high correlation coefficients (0.959-0.999). For the first time, reasonably low limits of detection (PAH 0.03-0.17 µg/kg; OPAH 0.04-0.43 µg/kg) were achieved, allowing the analysis of samples barbecued under practical relevant conditions. In charcoal grilled samples, the sum content of the seven detected OPAHs (5.7-62.4 µg/kg) was higher than the sum content of the six PAHs (1.4-36.7 µg/kg). However, 9,10-dihydro-8H-benzo[a]pyren-7-one was not detected in these samples.

Effect of short-chain chlorinated paraffins (SCCPs) on lipid membranes: Combination of molecular dynamics and membrane damage experiments

In recent years, more attention has been paid to the biological effects of short-chain chlorinated paraffin (SCCP). Studies have shown that SCCPs exposure could cause metabolic damage and lipid metabolic damage. In the present work, based on E. coli membrane damage experiments and molecular dynamics (MD) simulation, the effects of SCCPs on the membrane structure and membrane properties were studied to explore the possible toxic damage effects of SCCPs on cell membrane. Experiments results showed that SCCPs had a significant inhibitory effect on E. coli. The E. coli cell membrane of the bacteria was broken and the macromolecules of the cell flowed out when exposed to SCCPs. SCCPs would lead to the decrease and depolarization of cell membrane potential, and then affect the integrity and permeability of cell membrane. The further molecular dynamic simulation revealed that SCCP molecules can easily enter the lipid DPPC membranes from the aqueous phase and tended to aggregate inside bilayer stably. The bound of SCCPs could lead to significant variations in DPPC bilayer with a less dense, more disorder and rougher layer, which thus made the damage of cell membrane. In a word, although the overall toxicity of SCCPs to cell was relatively weak, the damage to the cell membrane may be one of the mechanisms of its toxicity. MAIN FINDING OF THE WORK: The exposure of SCCPs could cause structural change of cell membrane in E. coli, which verified the damage to the cell membrane may be one of the mechanisms of its toxicity.

Endothelial dysfunction and transcriptome aberration in mouse aortas induced by black phosphorus quantum dots and nanosheets

Black phosphorus (BP) nanomaterials have shown great potential in versatile applications including biomedicine and potentially interact with vessel walls following intravenous injection in biomedical usage or environmental exposure. However, it remains unknown whether the exposure to BP nanomaterials induces alterations of the endothelium and further vascular injury. Herein, the endothelial function of human umbilical vein endothelial cells (HUVECs) and the structure and transcriptome of C57BL/6 mouse aortas are evaluated after the exposure to BP quantum dots (BPQDs) and nanosheets (BPNSs). BPNSs with irregular shapes and larger lateral size are more prone to inhibit in vitro angiogenesis at non-cytotoxic concentrations and markedly trigger platelet adhesion to HUVECs compared to BPQDs. Decreased nitric oxide (NO) production resulting from endothelial NO synthase (eNOS) dysregulation is involved in the BP-induced endothelial dysfunction. Both BPQDs and BPNSs at 0.8 and 6.4 μg mL-1 inhibit eNOS enzymatic activity through dephosphorylation of eNOS-Ser1177 and phosphorylation of eNOS-Thr495, but unlike BPQDs, BPNSs also downregulate eNOS expression. Despite no pathological damage in the structure of mouse aortas, BPQDs and BPNSs trigger aberration of aortic transcriptome involved in vasoconstriction abnormality, metabolic disturbance, and immune perturbation. This study demonstrates the adverse effect of BP nanomaterials on vasculature, and suggests that the morphological attribute of BP plays a crucial role in the vascular risks.

Developmental toxicity of the novel PFOS alternative OBS in developing zebrafish: An emphasis on cilia disruption

In recent years, sodium p-perfluorous nonenoxybenzene sulfonate (OBS) has emerged as a substitute for PFOS with large demand and application in the Chinese market. However, little is known about potential developmental effects of OBS. In this study, zebrafish embryos were acutely exposed to different concentrations of OBS and the positive control PFOS for a comparative developmental toxicity assessment. OBS caused hatching delays, body axis curvature, neurobehavioral inhibition and abnormal cardiovascular development. These organismal effects were accompanied by change of development related genes expression profile, in which some cases were similar to PFOS. Overall, the toxic effects induced by OBS were generally milder than that of PFOS. Further investigation suggested that both OBS and PFOS disrupted ciliogenesis, evidenced by the ciliary immunostaining, changes in gene expression of kinesin family, dynein arm family and tubulin family members, as well as downregulation of the abundance of motor proteins including KIF3C, DYNC1H1 and DYNC1LI1. The influence of PFOS was stronger than that of OBS on ciliary genes and proteins. Molecular docking analysis revealed that both OBS and PFOS fitted into the motor proteins tightly, but binding affinity between OBS and motor proteins was lower than PFOS. Collectively, OBS and PFOS may act on ciliary motor proteins to interfere with ciliogenesis, leading to ciliary dysfunction and providing a novel probable action mode linked to developmental toxicity. This raises concerns regarding the health risks of the novel PFOS alternative OBS.

Comprehensive detection of nitrated aromatic compounds in fine particulate matter using gas chromatography and tandem mass spectrometry coupled with an electron capture negative ionization source

Nitrated aromatic compounds (NACs) are toxic and allergenic airborne pollutants from both primary emissions and atmospheric reactions of aromatics with NO₂. A comprehensive investigation of NACs is challenging given their low ambient levels. By applying gas chromatography and tandem mass spectrometry coupled with an electron capture negative ionization source, this study achieved a comprehensive high-throughput and standard-independent detection of nonpolar NACs in fine particulate matter (PM_2.5) sampled over 2 years in Beijing, China. Overall, 1047 NACs were detected, among which, the elemental composition of 128 species were derived using time-of-flight mass spectrometry, and 25 species were confirmed using reference standards. In addition to mono-nitrated polycyclic aromatic hydrocarbons (NPAHs), di-nitrated PAHs and alkylated and oxygenated NPAHs were found. Cluster analysis suggested these compounds were derived from various sources particularly atmospheric reactions. We found that the annual levels of primary NPAHs decreased by 46.3-54.8% from 2012-2013 to 2016-2018, though the secondary species did not change significantly after normalization by PM_2.5. These results were validated by diagnostic ratios, which indicated an increasing contribution from the secondary formation including nighttime reactions. This novel method for NACs detection may provide valuable insights into the formation mechanisms of NACs in the atmosphere.

Biodegradation mechanism of polycaprolactone by a novel esterase MGS0156: a QM/MM approach

Nowadays micro-plastic pollution has become one of the most serious global environmental problems. A potential strategy in managing micro-plastic waste is enzyme-catalyzed degradation. MGS0156 is a hydrolase screened from environmental metagenomes, which can efficiently degrade commercial plastics such as polycaprolactone, polylactide, etc. Here a combined molecular dynamics, molecular mechanics Poisson-Boltzmann surface area, and quantum mechanics/molecular mechanism method was used to reveal the enzymatic depolymerization mechanism. By systematically analyzing the binding processes of nine oligomers (from a monomer to tetramer), we found that longer oligomers have relatively stronger binding energy. The degradation process involves two concerted elementary steps: triad-assisted nucleophilic attack and C-O bond cleavage. C-O bond cleavage is the rate determining step with an average barrier of 15.7 kcal mol-1, which is consistent with the experimentally determined kcat (1101 s-1, corresponds to 13.3 kcal mol-1). The electrostatic influence analysis of twenty amino acids highlights His231 and Asp237 as potential mutation targets for designing more efficient MGS0156 mutants.

Field study of PAHs with their derivatives emitted from e-waste dismantling processes and their comprehensive human exposure implications

Extensive electronic waste (e-waste) recycling might be an important emission source of polycyclic aromatic hydrocarbons (PAHs) mixture, which might induce negative effects on the employees. In the present work, atmospheric pollution patterns of PAHs and their derivatives were determined in five different workshops to dismantle waste printed circuit boards (WPCBs) via thermal treatment. The results showed that mass concentrations of PAHs, chlorinated PAHs (ClPAHs), brominated PAHs (BrPAHs), oxy-PAHs (OPAHs) as well as carbazole (CBZ) were ranged from 1.53 × 10⁴-2.02 × 10⁵, 32.3-364, 8.29-1.13 × 10³, 923-1.39 × 10⁴ and 225-1.95 × 10³ pg·m^-3, respectively. Electric heating furnaces (EHF) workshops emitted relatively higher contaminants than other disposal sectors. OPAHs was found to be the most predominant derivatives of PAHs with 9,10-anthraquinone (83.0%) has the absolute superior in EHFTV, while benzo(a)anthracene-7,12-dione (>45.0%) was found to be the highest congener in other workshops, respectively. 9,10-Cl₂Phe exhibited the largest contributions to the ΣClPAHs whereas the composition profiles of BrPAHs varied among five workshops. In addition to direct chlorination of parent PAHs, thermal degradation of halogenated flame retardants incorporated into plastic materials might dominate the generation of Cl/BrPAHs from e-waste dismantling activities. The specific isomeric ratios of BrPAHs (3-BrFlu/1-BrPyr and 1-BrPyr/3-BrFlu) might be used to discriminate other emission sources from pyrolysis of WPCBs. However, their specific application as novel tracers for source identification should be further verified with more studies. The emitted PAHs mixture with their derivatives in all dismantling workshops posed carcinogenic risks to these dismantling workers via inhalation, particularly the workshop using electric heating furnaces to treat router. Nevertheless, new loadings of PAHs derivatives observed from e-waste dismantling activities, as well as their comprehensive health risk assessment provides us with a fresh perspective on the source appointment and potential adverse consequences of PAHs. More attention needs to be paid to the potential carcinogenic risks of exposure to PAHs and their derivatives from e-waste dismantling processes.

Pentabromoethylbenzene Exposure Induces Transcriptome Aberration and Thyroid Dysfunction: In Vitro, in Silico, and in Vivo Investigations

Pentabromoethylbenzene (PBEB), as one of the novel brominated flame retardants (NFBRs), has caused increasing public concern for health risks. Till now, information regarding potential effects of PBEB on thyroid function remains unclear. Herein, we investigated thyroid disruption of PBEB in vitro and in silico and evaluated thyroid dysfunction induced by PBEB using Sprague-Dawley rats. PBEB showed thyroid receptor (TR) β antagonistic activity with IC₅₀ of 9.82 × 10^-7 M in the dual-luciferase reporter gene assay and induced relative reorientation of helix 11 (H11) and H12 of the TR ligand binding domain as revealed by molecular dynamics simulations. PBEB (0.2, 2, 20 mg/kg BW/d) markedly altered the transcriptome profile of thyroid with induction of 17, 42, and 119 differentially expressed genes (DEGs) involved in thyroid hormone signaling and synthesis pathway, of which transthyretin and albumin are common DEGs. The 28-d exposure to PBEB significantly decreased the triiodothyronine level (from 7.23 to 5.67 ng/mL) and increased the thyrotropin level (from 7.88 to 12.86 mU/L) for female rats. PBEB consequently reduced thyroid weight and altered its morphology with more depleted follicles. Overall, our study provides the first account of evidence on PBEB exerted thyroid disruption, transcriptome aberration, and morphological alteration, facilitating health risk assessment of PBEB and structurally related NBFRs.

Fluoroacetate dehalogenase catalyzed dehalogenation of halogenated carboxylic acids: A QM/MM approach

Dehalogenation is one of the most important reactions in environmental pollution control, for instance, the degradation of persistent organic pollutants (POPs). Recently, fluoroacetate dehalogenase (FAcD) has been reported to catalyze the dehalogenation reactions, which shows great potential in treating halogenated pollutants. Here the dehalogenation mechanism catalyzed by FAcD was fully deciphered with the aid of quantum mechanics/molecular mechanics method. The results show that FAcD catalyzed dehalogenation efficiency follows the order of defluorination > dechlorination > debromination. The corresponding Boltzmann-weighted average barriers are 10.1, 19.7, and 20.9 kcal mol^-1. Positive/negative correlations between activation barriers and structural parameters (e.g. distance and angle) for FAcD catalyzed dechlorination and debromination were established. Based on the structure-energy relationship, we propose that mutation of the binding pocket amino acids (e.g. His155, Trp156, Tyr219) to smaller proton donor amino acids (e.g. Serine, Threonine, Cysteine, Asparagine) may increase the efficiency for dechlorination and debromination. The results may of practical value for the efficient degradation of chlorined and bromined pollutants by harnessing FAcD.

Elucidating the potential neurotoxicity of chiral phenthoate: Molecular insight from experimental and computational studies

Chiral organophosphorus pollutants are existed ubiquitously in the ecological environment, but the enantioselective toxicities of these nerve agents to humans and their molecular bases have not been fully elucidated. Using experimental and computational approaches, this story was to explore the neurotoxic response process of the target acetylcholinesterase (AChE) to chiral phenthoate and further decipher the microscopic mechanism of such toxicological effect at the enantiomeric level. The results showed that the toxic reaction of AChE with chiral phenthoate exhibited significant enantioselectivity, and (R)-phenthoate (K＝1.486 × 10⁵ M^-1) has a bioaffinity for the nerve enzyme nearly three times that of (S)-phenthoate (K＝4.503 × 10⁴ M^-1). Dynamic research outcomes interpreted the wet experiments, and the inherent conformational flexibility of the target enzyme has a great influence on the enantioselective neurotoxicological action processes, especially reflected in the conformational changes of the three key loop regions (i.e. residues His-447, Gly-448, and Tyr-449; residues Gly-122, Phe-123, and Tyr-124; and residues Thr-75, Leu-76, and Tyr-77) around the reaction patch. This was supported by the quantitative results of conformational studies derived from circular dichroism spectroscopy (α-helix: 34.7%→30.2%/31.6%; β-sheet: 23.6%→19.5%/20.7%; turn: 19.2%→22.4%/21.9%; and random coil: 22.5%→27.9%/25.8%). Meanwhile, via analyzing the modes of toxic action and free energies, we can find that (R)-phenthoate has a strong inhibitory effect on the enzymatic activity of AChE, as compared with (S)-phenthoate, and electrostatic energy (-23.79/－17.77 kJ mol^-1) played a critical role in toxicological reactions. These points were the underlying causes of chiral phenthoate displaying different degrees of enantioselective neurotoxicity.

Probing the Interaction between Human Serum Albumin and 9-Hydroxyphenanthrene: A Spectroscopic and Molecular Docking Study

9-Hydroxyphenanthrene (9-OHPhe), the representative hydroxyl metabolite of phenanthrene, has generated increasing concern as it is potentially hazardous to organisms. Herein, multispectroscopic and molecular docking techniques were applied to investigate the molecular interaction of human serum albumin (HSA) with 9-hydroxyphenanthrene (9-OHPhe) under simulated physiological conditions. Steady-state fluorescence and time-resolved fluorescence spectral analysis showed that 9-OHPhe quenched HSA fluorescence through a mixed static and dynamic process. HSA can bind with 9-OHPhe to form a 1:1 complex, with binding constants of 1.28 × 10⁵, 1.36 × 10⁵, and 1.26 × 10⁵ L·mol^-1 at 298.15, 303.15, and 308.15 K, respectively. The strong binding between HSA and 9-OHPhe is spontaneous and entropy-driven. Molecular docking indicated that the optimal binding site of 9-OHPhe with HSA was located in the IA subdomain of HSA. Thermodynamic analysis and molecular docking results suggested that hydrophobic interactions and hydrogen bond force dominated the binding process of HSA with 9-OHPhe. Specifically, 9-OHPhe formed hydrophobic interactions with LEU134, LEU139, ILE142, LEU154, PHE157, ALA158, and TYR161 and formed a 1.86 Å hydrogen bond with LEU135. Circular dichroism spectral analysis showed that the α-helical content of HSA decreased from 52.3 to 50.9% after adding 9-OHPhe with a ratio of 1:1. The obtained results are hoped to provide basic data for understanding the potential effects of the hydroxyl metabolites of PAHs on functional biomacromolecules.