Interactions between hydroxylated polycyclic aromatic hydrocarbons and serum albumins: multispectral and molecular docking analyses.

Hydroxylated polycyclic aromatic hydrocarbons (OH-PAHs) can bind to serum albumin and influence their distribution and elimination in organisms. Here, multispectral analysis and molecular docking methods were used to investigate the binding mechanism of two OH-PAHs, 1-hydroxyphenanthrene (1-OHPhe) and 9-hydroxyphenanthrene (9-OHPhe), with two homologous serum albumins, human serum albumin (HSA) and bovine serum albumin (BSA). The quenching constants of HSA with 1-OHPhe and 9-OHPhe were much larger than those for BSA. Energy transfer from the tryptophan (Trp) residues in HSA to 1-OHPhe and 9-OHPhe was more probable than from Trp in BSA. The interactions of 1-OHPhe and 9-OHPhe with Trp in HSA and BSA altered the microenvironment of Trp. Molecular docking results revealed that the binding modes and binding forces of 1-OHPhe and 9-OHPhe with HSA and BSA were different. The two OH-PAHs were used as fluorescent probes to analyze the microenvironmental hydrophobicities of HSA and BSA, which were distinctly different. The structural difference between HSA and BSA induced significant variations in their binding behaviour with 1-OHPhe and 9-OHPhe. Moreover, HSA was more susceptible to 1-OHPhe and 9-OHPhe than BSA. This work suggests that the differences between the two serum albumins should be considered in related studies.

[Adsorption mechanism of typical monohydroxyphenanthrene on polyvinyl chloride microplastics].

To enrich data related to the interaction mechanism between microplastics and organic pollutants, in this study, 3-hydroxy-phenanthrene (3-OHP, C14H10O), a phenanthrene derivative, was selected as a representative pollutant, and polyvinyl chloride (PVC) microplastics were chosen as the research objects. We investigated the adsorption behavior of 3-OHP on PVC microplastics in aqueous solutions and explored the adsorption mechanism in detail. The PVC microplastics were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared (FT-IR) spectroscopy. The standard curves of the ultraviolet (UV) absorption spectrum of the target pollutant were obtained using a UV spectrophotometer. The fitting coefficient values of all standard curves were higher than 0.99 (R2>0.99). To ensure the accuracy of the UV absorption spectrum, the pollutant concentration gradient was set according to the absorbance (Abs) values, which were higher than 0.438. The measured concentrations were calculated using a standard curve equation. The adsorption mechanism of 3-OHP on PVC microplastics in an aqueous solution was studied by combining adsorption models (adsorption kinetics model, adsorption isotherm model, and adsorption thermodynamics model) and density functional theory (DFT) calculations. The results are as follows: (1) From the adsorption kinetics experiment, the pseudo-second-order kinetic model had the best fitting degree, and the fitting coefficient of adsorption kinetics was 0.998 (R2=0.998). Hence, 3-OHP adsorption on PVC microplastics may be attributed to surface adsorption and external liquid film diffusion; the equilibrium adsorption amount was 36.866 µg/g after 24 h. (2) The adsorption isotherm experiment showed that the Langmuir and Freundlich isotherm models were more suitable for describing the adsorption mechanism of 3-OHP adsorption on PVC microplastics because of the satisfactory fitting coefficient (R 2=0.956 and 0.907), suggesting that the adsorption mode was mainly single-layer adsorption with a small amount of multilayer adsorption. The maximum adsorption amount of 3-OHP adsorption on PVC microplastics was 408 µg/g; (3) the adsorption thermodynamics results showed that the adsorption efficiency of 3-OHP adsorption on PVC microplastics decreased with increasing temperature, indicating that the adsorption of 3-OHP on PVC microplastics was a spontaneous and exothermic adsorption process; (4) the salinity experiment results showed that salinity had little effect on the adsorption efficiency of 3-OHP on PVC microplastics; (5) DFT calculations showed that PVC had a relatively low binding energy to 3-OHP. Therefore, we suggest that the main adsorption mechanism of 3-OHP on PVC microplastics may be the hydrophobic effect; weak hydrogen bonding, halogen bonding, and π-π conjugate action could also play a role in 3-OHP adsorption on PVC. These results reveal the interaction mechanism between PVC microplastics and organic chemicals, and enhance our understanding of the environmental behavior of PVC microplastics in aqueous solutions. To serve as a reference in scientific evaluations of the environmental impact of microplastics, future studies should focus on obtaining toxicological data for the microplastics.

Benchmark dose analysis for PAHs hydroxyl metabolites in urine based on mitochondrial damage of peripheral blood leucocytes in coke oven workers in China.

OBJECTIVES: The aim was to explore the dose-response relationship between occupational polycyclic aromatic hydrocarbons (PAHs) exposure and mitochondrial damage in coke oven plants workers. METHODS: 544 workers and 238 healthy people were recruited. The ultra-high performance liquid chromatography was used to determine the level of 1-hydroxypyrene, 1-hydroxynaphthalene, 2-hydroxynaphthalene and 3-hydroxyphenanthrene. The real-time fluorescence quantitative polymerase chain reaction was used to determine the mitochondrial DNA copy number (mtDNAcn). The benchmark dose software was used to analyze the benchmark dose. RESULTS: The mtDNAcn in the exposure group was lower than that in the control group. The concentrations of 1-hydroxypyrene, 1-hydroxynaphthalene, 2-hydroxynaphthalene and 3-hydroxyphenanthrene in the exposure group were higher than those in the control group. There is a dose-response relationship between 1-hydroxypyrene, 3-hydroxyphenanthrene and mitochondrial DNA damage. The benchmark dose lower confidence limit (BMDL) of 1-hydroxypyrene were 0.045, 0.004, and 0.058 pg/µg creatinine in the total, male, and female population, respectively. The BMDL of 3-hydroxyphenanthrene were 5.142, 6.099, and 2.807 pg/µg creatinine in the total, male, and female population, respectively. CONCLUSIONS: The BMDL of 1-hydroxypyrene and 3-hydroxyphenanthrene initially explored can provide a reference to establish occupational exposure biological limits.

Adsorption of phenanthrene and its monohydroxy derivatives on polyvinyl chloride microplastics in aqueous solution: Model fitting and mechanism analysis.

The pervasiveness of microplastics, which can absorb pollutants, has a certain impact on pollutant migration in natural waters. Differences in functional groups, such as the hydroxyl group, of pollutants will affect their adsorption on microplastics. In this study, the adsorption of phenanthrene (PHE) or its monohydroxy derivatives, including 1-hydroxyphenanthrene (1-OHP), 2-hydroxyphenanthrene (2-OHP), 4-hydroxyphenanthrene (4-OHP), and 9-hydroxyphenanthrene (9-OHP), on polyvinyl chloride (PVC, measured mean particle size = 134 µm) microplastics was studied. The adsorption efficiency of PHE was shown to be higher than that of either of OHPs. A better fit for pseudo-second-order and Freundlich isotherm models was obtained, indicating different binding sites on the surface of PVC microplastics. The adsorption processes of PHE and OHPs on PVC microplastics were demonstrated to be exothermic and spontaneous. Combined with FT-IR analysis, theoretical calculation, and comparative adsorption experiments, hydrophobic interaction was the dominant mechanism during the adsorption process. In contrast, electrostatic repulsion, CH/π interaction, and halogen bonding played a minor role, to an extent, in the adsorption of PHE/OHPs on PVC microplastics. These findings indicate the influence of the hydroxyl group on adsorption and improve the understanding of interactions between PVC microplastics and PHE/OHPs.

Study on the molecular interactions of hydroxylated polycyclic aromatic hydrocarbons with catalase using multi-spectral methods combined with molecular docking.

To reveal the potential effects of hydroxylated polycyclic aromatic hydrocarbons (OH-PAHs) on catalase (CAT), the interactions of 1-hydroxynaphthalene (1-OHNap), 9-hydroxyphenanthrene (9-OHPhe) and 1-hydroxypyrene (1-OHPyr) with CAT were investigated using multi-spectroscopic and molecular docking techniques. Fluorescence analysis showed that 1-OHNap, 9-OHPhe and 1-OHPyr can form 1:1 complex with CAT, with the binding constant of 6.31 × 103, 1.03 × 104 and 2.96 × 105 L mol-1 at 17 °C. Thermodynamic and docking parameters demonstrated that van der Waals' force, hydrogen bonds and hydrophobic interactions dominated the three binding processes. Molecular docking also revealed the specific binding mode of OH-PAHs with CAT. Synchronous fluorescence and circular dichroism spectral results indicated that the three OH-PAHs induced varied structural changes of CAT. Furthermore, CAT activity was promoted by 9-OHPhe, but inhibited by either 1-OHNap or 1-OHPyr. Under the maximum experimental concentration of OH-PAHs, the percent change of CAT activity induced by 1-OHNap, 9-OHPhe and 1-OHPyr were 8.42%, 4.26% and 13.21%.

Involvement of transient receptor potential melastatin 4 channels in the resting membrane potential setting and cholinergic contractile responses in mouse detrusor and ileal smooth muscles.

Here, we investigated the effects of 9-hydroxyphenanthrene (9-phenanthrol), a potent and selective transient receptor potential melastatin 4 (TRPM4) channel blocker, on the resting membrane potential and cholinergic contractile responses to elucidate the functional role of TRPM4 channels in the contractile activities of mouse detrusor and ileal longitudinal smooth muscles. We observed that, 9-phenanthrol (3-30 µM) did not significantly inhibit high K+-induced contractions in both preparations; however, 9-phenanthrol (10 µM) strongly inhibited cholinergic contractions evoked by electrical field stimulation in detrusor preparations compared to inhibitions in ileal preparations. 9-Phenanthrol (10 µM) significantly inhibited the muscarinic agonist, carbachol-induced contractile responses and slowed the maximum upstroke velocities of the contraction in detrusor preparations. However, the agent (10 µM) did not inhibit the contractions due to intracellular Ca2+ release evoked by carbachol, suggesting that the inhibitory effect of 9-phenanthrol may primarily be due to the inhibition of the membrane depolarization process incurred by TRPM4 channels. On the other hand, 9-phenanthrol (10 µM) did not affect carbachol-induced contractile responses in ileal preparations. Further, 9-phenanthrol (10 µM) significantly hyperpolarized the resting membrane potential and decreased the basal tone in both detrusor and ileal muscle preparations. Taken together, our results suggest that TRPM4 channels are constitutively active and are involved in setting of the resting membrane potential, thereby regulating the basal tone in detrusor and ileal smooth muscles. Thus, TRPM4 channels play a significant role in cholinergic signaling in detrusor, but not ileal, smooth muscles.

Exposure characterization and estimation of benchmark dose for cancer biomarkers in an occupational cohort of diesel engine testers.

Exposure to diesel engine exhaust (DEE) was associated with various adverse health effects including lung cancer. Particle size distribution and profiles of organic compounds in both particle and gas phases of DEE that could provide valuable insights into related health effects were measured in a diesel engine testing workshop. Concentrations of urinary 6 mono-hydroxylated polycyclic aromatic hydrocarbons (OH-PAHs) in 137 DEE-exposed workers and 127 non-DEE-exposed workers were determined. Benchmark dose method was applied to estimate lower limit of benchmark dose (BMDL) of urinary OH-PAHs most specific to DEE exposure for previously reported cancer biomarkers. We found that 84.3% of diesel exhaust particles were ultrafine particles. Indeno[123-cd]pyrene and phenanthrene were the most abundant carcinogenic and noncarcinogenic PAHs in the particle phase of DEE, respectively. Principal component analysis demonstrated that urinary hydroxyphenanthrene (OHPhe) had highest loading value on principal component (PC) representative of DEE exposure and lowest loading value on PC representative of smoking status. BMDLs of urinary OHPhe from best-fitting models for cancer biomarkers including micronucleus and 1,N6-ethenodeoxyadenosine were 1.08 µg/g creatinine and 2.82 µg/g creatinine, respectively. These results provided basis for understanding DEE exposure induced health effects and potential threshold for regulating DEE levels in an occupational setting.

Epigallocatechin-3-gallate and 6-OH-11-O-Hydroxyphenanthrene Limit BE(2)-C Neuroblastoma Cell Growth and Neurosphere Formation In Vitro.

We conducted an in vitro study combining a rexinoid, 6-OH-11-O-hydroxyphenanthrene (IIF), and epigallocatechin-3-gallate (EGCG), which is the main catechin of green tea, on BE(2)-C, a neuroblastoma cell line representative of the high-risk group of patients. Neuroblastoma is the most common malignancy of childhood: high-risk patients, having N-MYC over-expression, undergo aggressive therapy and show high mortality or an increased risk of secondary malignancies. Retinoids are used in neuroblastoma therapy with incomplete success: the association of a second molecule might improve the efficacy. BE(2)-C cells were treated by EGCG and IIF, individually or in combination: cell viability, as evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay, was reduced, EGCG+IIF being the most effective treatment. Apoptosis occurred and the EGCG+IIF treatment decreased N-MYC protein expression and molecular markers of invasion (MMP-2, MMP-9 and COX-2). Zymography demonstrated nearly 50% inhibition of MMP activity. When BE(2)-C cells were grown in non-adherent conditions to enrich the tumor-initiating cell population, BE(2)-C-spheres were obtained. After 48 h and 72 h treatment, EGCG+IIF limited BE(2)-C-sphere formation and elicited cell death with a reduction of N-MYC expression. We concluded that the association of EGCG to IIF might be applied without toxic effects to overcome the incomplete success of retinoid treatments in neuroblastoma patients.

Comparison of gaseous polycyclic aromatic hydrocarbon metabolites according to their specificity as biomarkers of occupational exposure: Selection of 2-hydroxyfluorene and 2-hydroxyphenanthrene.

Exposure to Polycyclic Aromatic Hydrocarbons (PAHs) occurs by respiratory, digestive and dermal absorption. Biomonitoring takes all pathways into account but sensitive and specific biomarkers are required. Different gaseous PAHs metabolites were used due to their abundance in the atmospheric mixtures but none of them were selected as better biomarker than the others. To identify the best candidates for assessing occupational airborne exposure, relation between atmospheric levels of Naphtalene, Fluorene and Phenanthrene and urinary metabolites concentrations was studied in a carbon electrode workers group. Linear mixed effects models were built to select explanatory variables and estimate variance component. Urinary creatinine was a predictor of metabolites levels confirming the importance of diuresis for interpreting results. High significance of pre-shift sampling time combined with positive coefficients of post-shift indicated that urine should be sampled at the end of the workday in association with pre-shift urine to avoid misinterpretations. Among the 10 metabolites studied, urinary 2-hydroxyfluorene and 2-hydroxyphenanthrene showed the highest increase of variance explained by models after inclusion of individual atmospheric levels as explanatory variable. Priority could be given to 2-hydroxyfluorene due to higher excretion levels than 2-hydroxyphenanthrene.

Association of polycyclic aromatic hydrocarbons metabolites and risk of diabetes in coke oven workers.

Elevated polycyclic aromatic hydrocarbons (PAHs) metabolites have recently been linked to increased risk of diabetes in the general population, but little is known about the risk of diabetes due to high pollution levels of PAHs exposure. We aimed to examine whether occupational exposure to PAHs would be one of the important risk factors for diabetes in the coke oven workers. A total of 1472 coke oven workers with complete data were qualified for the present study. We measured 12 urinary monohydroxy polycyclic aromatic hydrocarbons (OH-PAHs) by gas chromatography-mass spectrometry (GC-MS). Multiple logistic regression was used to evaluate the associations between urinary OH-PAHs and risk of diabetes, with adjustment for the potential confounders. We found that elevated urinary 4-hydroxyphenanthrene (4-OHPh) was significantly associated, in a dose-dependent manner, with increased risk of diabetes (Ptrend = 0.003). Compared with individuals with 4-OHPh in the lowest quartile, the adjusted odds ratio (OR) of diabetes among those in the highest quartile was 2.80 (95% CI = 1.37-5.71). In stratified analysis, the association was more prominent in those who were smokers, overweight (BMI ≥24 kg/m2), with longer working years (≥20 years) and worked at coke oven settings. In addition, high levels of 4-OHPh combined with longer working years or overweight had a joint effect on the risk of diabetes. Our data suggested that elevated 4-OHPh was dose-responsive associated with increased risk of diabetes in the coke oven workers. The risk assessment of diabetes related to occupational PAHs exposure should take working years and BMI into consideration.

Influencing factors of urinary hydroxyl metabolites of polycyclic aromatic hydrocarbons in coke oven workers / 中国职业医学

OBJECTIVE: To observe the levels of four hydroxylated metabolites of polycyclic aromatic hydrocarbons(PAHs)in the urine of coke workers and its influencing factors.To explore the feasibility of using PAHs as biomarkers for exposure of coke oven emissions(COEs).METHODS: A cross-sectional survey was used to compare 261 coke oven workers in a coke oven plant as exposure group with 111 workers without COEs exposure in an oxygen making plant as control group.Ultra high liquid chromatography-mass spectrometry was used to detect four hydroxylated metabolites of PAHs,including1-hydroxypyrene(OHP),1-hydroxynaphthalene(OHN),2-OHN and 3-hydroxyphenanthrene,in urine of these two groups.RESULTS: The levels of four hydroxylated metabolites of PAHs in urine in exposure group were higher than that of the control group(P<0.01).The levels of urinary 1-OHP,1-OHN,2-OHN were followed by the sequence of bottomoven,side-oven,and top-oven subgroups among the exposure group(P<0.05).The multiple linear regression results indicated that the levels of urinary 1-OHP,1-OHN,2-OHN were correlated with COEs exposure(P<0.05),after adjusting the confounding factors of gender,age,length of service,smoking status and alcohol drinking status.The levels of urinary 1-OHP,1-OHN,2-OHN of the exposure group increased with the increase of COEs exposure levels showing a dose-effect relationship(P<0.01).The levels of 1-OHN and 2-OHN were associated with smoking apart from COEs exposure(P<0.01).CONCLUSION: The urinary 1-OHP can be used as a reliable biomarker for the evaluation of internal exposure to COEs.The 1-OHN and 2-OHN can be used as adjuvant biomarkers.

Polycyclic Aromatic Hydrocarbons: Part II, Urine Markers.

There has been increasing demand for simple, rapid, highly sensitive, inexpensive yet reliable method for detecting predisposition to cancer. Human biomonitoring of exposure to the largest class of chemical carcinogen, polycyclic aromatic hydrocarbons (PAHs) that are rapidly transformed into detectable metabolites (eg, 1-hydroxypyrene), can serve as strong pointers to early detection of predisposition to cancer. Given that any exposure to PAH is assumed to pose a certain risk of cancer, several biomarkers have been employed in biomonitoring these ninth most threatening ranked compounds. They include metabolites in urine, urinary thioethers, urinary mutagenicity, genetoxic end points in lymphocytes, hemoglobin adducts of benzo(a)pyrene, PAH-protein adducts, and PAH-DNA adducts among others. In this chapter, the main focus will be on the urine metabolites since urine samples are easily collected and there is a robust analytical instrument for the determination of their metabolites.

Association between polycyclic aromatic hydrocarbons and thyroid function among males and females: data from NHANES 2007-2008.

The objective of this study was to evaluate the association between thyroid function and exposure to selected polycyclic aromatic hydrocarbons (PAH) among those aged ≥ 20 years. Thyroid variables considered for evaluation were thyroid-stimulating hormone, free and total serum thyroxine (FT4, TT4), free and total triiodothyronine (FT3, TT3), and thyroglobulin. PAH metabolites in urine for which data were analyzed were 1-hydroxynaphthalene, 2-hydroxynaphthalene, 2-hydroxyfluorene, 3-hydroxyfluorene, 9-hydroxyfluorene, 1-hydroxyphenanthrene, 2-hydroxyphenanthrene, 3-hydroxyphenanthrene, and 1-hydroxypyrene. Using data from 2007 to 2008 National Health and Nutrition Examination Survey, regression models with logs of thyroid variables as dependent variables and PAH exposure, age, race/ethnicity, iodine sufficiency, smoking status, and others as independent variables were fitted. For females, increased levels of 2-hydroxynapthalene, 2-hydroxyphenanthrene, and 1-hydroxypyrene were associated with elevated levels of TT3. For males, increased levels of 1-hydroxyphenanthrene, 2-hydroxyphenanthrene, and 9-hydroxypyrene were associated with decreased levels of FT4.

Urinary polycyclic aromatic hydrocarbon metabolites levels in a representative sample of the Spanish adult population: The BIOAMBIENT.ES project.

In 2009, the Spanish Ministry of Agriculture, Food and Environment promoted the BIOAMBIENT.ES project, a Human Biomonitoring program on the national scale to estimate reference levels of environmental pollutants on a representative sample of the Spanish adults. The present study focuses on polycyclic aromatic hydrocarbons (PAHs). The urinary metabolites 1-hydroxypyrene, 1-,2-,3-,4- and 9-hydroxyphenanthrene and 3-hydroxybenzo[a]pyrene were selected as indicators of PAH exposure. Urine samples from 957 subjects (16-65 years old) were collected during year 2009-2010. Geometric mean and 95th percentile for 1-hydroxypyrene in µg g(-1) creatinine were 0.117 (non-smoker: 0.079, smokers: 0.184) and 0.67 µg g(-1) creatinine (non-smokers: 0.31, smokers: 0.69) respectively. GM and 95th percentile for sum of hydroxyphenanthrenes in µg g(-1) creatinine were 0.130 (non-smokers: 0.089, smokers: 0.317) and 1.29 (non-smokers: 0.71, smokers: 1.51) respectively. 3-Hydroxybenzo[a]pyrene was below the limit of quantitation (0.05 µg L(-1)) in all cases. Significant differences (p<0.05) regarding smokers and non-smokers, coal and wood heating, body mass index and second hand smoke were found, while other variables like gender, age, or diet showed no significant association. The geographical distribution of the metabolites showed higher levels in people who lived in the north and northwest of Spain. The PAH metabolites levels found were in the same range or lower than those reported from other European countries and they were higher than those found in the U.S. This study represents the first nationwide survey of exposure to PAHs in Spain and provides a background reference range for exposure to PAHs in the Spanish adult occupied population.

Studying the effects of polycyclic aromatic hydrocarbons on peripheral arterial disease in the United States.

PURPOSE: Polycyclic aromatic hydrocarbons are a group of prevalent pollutants which are produced by incomplete combustion of organic materials such as coal, fuel, tobacco smoking and food cooking. The associations between exposures to polycyclic aromatic hydrocarbons (PAHs) and peripheral arterial disease (PAD) have not been well studied. METHODS: We used the 2001-2004 National Health and Nutrition Examination Survey (NHANES) to investigate the associations between eight monohydroxy urinary metabolites of four PAHs and PAD. RESULTS: In a logistic regression model, subjects within the middle and highest tertiles of fluorene metabolites, 2-hydroxyfluorene (2-FLUO) and 3-hydroxyfluorene (3-FLUO), and phenanthrene metabolites, 1-hydroxyphenanthrene (1-PHEN) and 2-hydroxyphenanthrene (2-PHEN), had significantly higher prevalence of PAD as compared to subjects within the lowest tertile after adjusting for cigarette smoking, diabetes mellitus and other covariates (For 2-FLUO, the 3rd tertile: OR=2.22, 95% CI=1.13-4.37, p for trend=0.02; For 3-FLUO, the 3rd tertile: OR=2.36, 95% CI: 1.16-4.77, p for trend=0.02; For 1-PHEN, the 3rd tertile: OR=1.84, 95% CI: 1.01-3.37, p for trend=0.04; For 2-PHEN, the 3rd tertile: OR=1.76, 95% CI: 1.07-2.88, p for trend=0.03). CONCLUSIONS: Our findings suggest that exposure to PAHs may increase the risk of PAD. Further studies are necessary to explore the associations between PAHs and PAD.