Biosynthesis of the benzylpyrrolidine precursor in anisomycin by a unique ThDP-dependent enzyme.

Anisomycin (compound 1), a multifunctional pyrrolidine antibiotic, primarily inhibits protein biosynthesis by binding to the ribosome. Upon binding to the ribosome, the para-phenol moiety of anisomycin inserts completely into the hydrophobic crevice of the A-site and blocks the access of the incoming aminoacyl-tRNAs, disrupting peptide bond formation. Hence, the para-methoxyphenyl group serves as a starting point for developing novel anisomycin analogs with potent antifungal and insecticidal properties. However, the activation and condensation mechanism of phenylpyruvic acid has not yet been elucidated. In this study, genetic manipulations of aniP and its homologue siAniP confirmed their indispensable role in 1 biosynthesis. Bioinformatics analysis suggested that AniP and siAniP function as transketolase. siAniP was found to catalyzed condensation between 4-hydroxyphenylpyruvic acid (3) and glyceraldehyde (GA), initiating pyrrolidine synthesis. siAniP was specific for aromatic keto acids and tolerant of aliphatic and aromatic aldehydes, and was able to catalyze the asymmetric intermolecular condensation of two keto acids, leading to the formation of 24 α-hydroxy ketone. To the best of our knowledge, siAniP is the first TK that catalyzes the transfer of a C2 ketol and symmetrical intermolecular coupling using aromatic keto acids as donor substrates. Structural analysis, docking model construction, and site-directed mutagenesis identified that I220, H275, R322 and W391 were crucial for substrate binding. Moreover, sequence similarity network (SSN)-based genome neighborhood network (GNN) analyses of AniP suggested the widespread occurrence of the AniP-like-mediated reaction in the biosynthesis of 1 and its analogs, particularly in the assembly of benzylpyrrolidine. These findings not only expand the repertoire of TKs but also provide a potent biocatalyst that could be used for the structural innovation of 1 and its derivatives.

Preferential association of PBDEs and PAHs with mineral particles vs. dissolved organic carbon: Implications for groundwater contamination at e-waste sites.

Polybrominated biphenyl ethers (PBDEs) and polycyclic aromatic hydrocarbons (PAHs) are commonly detected contaminants at e-waste recycling sites. Against the conventional wisdom that PBDEs and PAHs are highly immobile and persist primarily in shallow surface soils, increasing evidence shows that these compounds can leach into the groundwater. Herein, we compare the leachabilities of PBDEs vs. PAHs from contaminated soils collected at an e-waste recycling site in Tianjin, China. Considerable amounts of BDE-209 (0.3-2 ng/L) and phenanthrene (42-106 ng/L), the most abundant PBDE and PAH at the site, are detected in the effluents of columns packed with contaminated soils, with the specific concentrations varying with hydrodynamic and solution chemistry conditions. Interestingly, the leaching potential of BDE-209 appears to be closely related to the release of colloidal mineral particles, whereas the leachability of phenanthrene correlates well with the concentration of dissolved organic carbon in the effluent, but showing essentially no correlation with the concentration of mineral particles. The surprisingly different trends of the leachability observed between BDE-209 and phenanthrene is counterintuitive, as PBDEs and PAHs often co-exist at e-waste recycling sites (particularly at the sites wherein incineration is being practiced) and share many similarities in terms of physicochemical properties. One possible explanation is that due to its extremely low solubility, BDE-209 predominantly exists in free-phase (i.e., as solid (nano)particles), whereas the more soluble phenanthrene is mainly sorbed to soil organic matter. Findings in this study underscore the need to better understand the mobility of highly hydrophobic organic contaminants at contaminated sites for improved risk management.

Associations of polycyclic aromatic hydrocarbons exposure with serum uric acid and hyperuricemia in US adults: The role of systemic inflammation.

The associations of polycyclic aromatic hydrocarbon (PAH) exposure with serum uric acid (SUA) or hyperuricemia have been rarely assessed. We aimed to investigate the relationships between urinary PAH metabolites and SUA or hyperuricemia among US adults and to explore the mediating role of systemic inflammation in the associations. A total of 10,307 US adults were conducted to assess the associations of seven urinary hydroxy­PAH with SUA and hyperuricemia and evaluate the role of C-reactive protein (CRP), a biomarker of systemic inflammation, in such associations. Results showed that each 1-unit increase in ln-transformed 2-hydroxynaphthalene (2-OHNa), 1-hydroxyphenanthrene (1-OHPh), 2&3-hydroxyphenanthrene (2&3-OHPh) and total hydroxyphenanthrene (ΣOHPh) was associated with a 1.68 (95% confidence interval (CI): 0.19 to 3.17), 2.46 (0.78 to 4.13), 3.34 (1.59 to 5.09), and 2.99 (1.23 to 4.75) µmol/L increase in SUA, and a 8% (odds ratio (OR): 1.08, 1.02 to 1.15), 9% (OR: 1.09, 1.02 to 1.18), 13% (OR: 1.13, 1.05 to 1.22), and 12% (OR: 1.12, 95% CI: 1.03, 1.21) increase in hyperuricemia, respectively. Co-exposure of seven PAHs was positively associated with SUA and hyperuricemia, with 2&3-OHPh showing the highest weight (components weights: 0.83 and 0.78, respectively). The CRP mediated 11.47% and 10.44% of the associations of ΣOHPh and 2&3-OHPh with SUA and mediated 8.60% and 8.62% in associations of ΣOHPh and 2&3-OHPh with hyperuricemia, respectively. In conclusion, internal levels of PAH metabolites were associated with elevated SUA levels and the increased risk of hyperuricemia among US adults, and CRP played a mediating role in the associations.

Facile synthesis of magnetic ionic covalent organic framework and dispersive magnetic solid phase extraction of aromatic amino acid oxidation products in thermally processed foods.

Aromatic amino acid oxidation products (AAAOPs) are newly discovered risk substances of thermal processes. Due to its significant polarity and trace level in food matrices, there are no efficient pre-treatment methods available to enrich AAAOPs. Herein, we proposed a magnetic cationic covalent organic framework (Fe3O4@EB-iCOF) as an adsorbent for dispersive magnetic solid-phase extraction (DMSPE). Benefiting from the unique charged characteristics of Fe3O4@EB-iCOF, AAAOPs can be enriched through electrostatic interaction and π-π interactions. Under the optimal DMSPE conditions, the combined HPLC-MS/MS method demonstrated good linearity (R2 ≥ 0.990) and a low detection limit (0.11-7.5 µg·kg-1) for AAAOPs. In addition, the method was applied to real sample and obtained satisfactory recoveries (86.8 % âˆ¼ 109.9 %). Especially, we applied this method to the detection of AAAOPs in meat samples and conducted a preliminarily study on its formation rules, which provides a reliable basis for assessing potential dietary risks.

Examination of primary aromatic amines content in polylactic acid straws and migration into food simulants using SERS with LC-MS.

Polylactic acid (PLA) straws hold eco-friendly potential; however, residual diisocyanates used to enhance the mechanical strength can generate carcinogenic primary aromatic amines (PAAs), posing health risks. Herein, we present a rapid, comprehensive strategy to detecting PAAs in 18 brands of food-grade PLA straws and assessing their migration into diverse food simulants. Surface-enhanced Raman spectroscopy was conducted to rapidly screen straws for PAAs. Subsequently, qualitative determination of migrating PAAs into various food simulants (4 % acetic acid, 10 % ethanol, 50 % ethanol) occurred at 70 °C for 2 h using liquid chromatography-mass spectrometry. Three PAAs including 4,4'-methylenedianiline, 2,4'-methylenedianiline, and 2,4-diaminotoluene were detected in all straws. Specifically, 2,4-diaminotoluene in 50 % ethanol exceeded specific migration limit of 2 µg/kg, raising safety concerns. Notably, PAAs migration to 10 % and 50 % ethanol surpassed that to 4 % acetic acid within a short 2-hour period. Moreover, PLA straws underwent varying degrees of shape changes before and after migration. Straws with poly(butylene succinate) resisted deformation compared to those without, indicating enhanced heat resistance, while poly(butyleneadipate-co-terephthalate) improved hydrolysis resistance. Importantly, swelling study unveiled swelling effect wasn't the primary factor contributing to the increased PAAs migration in ethanol food simulant, as there was no significant disparity in swelling degrees across different food simulants. FT-IR and DSC analysis revealed higher PAAs content in 50 % ethanol were due to highly concentrated polar ethanol disrupting hydrogen bonds and van der Waal forces holding PLA molecules together. Overall, minimizing contact between PLA straws and alcoholic foods is crucial to avoid potential safety risks posed by PAAs.

Vibrational spectroscopy of interstellar PAHs: 1-cyanonaphthalene and 2-cyanonaphthalene.

In this work, we present a comprehensive experimental and theoretical study of the vibrational spectra of PAH molecules recently detected in the interstellar medium: 1-cyanonaphthalene and 2-cyanonaphthalene. The room temperature IR spectra of 1- and 2-cyanonaphthalene in the region 100-3100 cm-1 and their vibrational Raman spectra in the region 35-3100 cm-1 are reported here for the first time. A detailed spectral analysis is carried out using quantum chemical calculations employing the DFT methodology. Anharmonic corrections using the VPT2 method yield excellent agreement with the experimental spectra. A re-investigation of the vibrational spectrum of the parent molecule: naphthalene validates the experimental and theoretical methods used. A consistent set of assignments is reported for the fundamental bands of 1- and 2-cyanonapththalene. The experimental and theoretical data presented here would be useful inputs for modelling the role of cyanonaphthalene in astrophysical processes.

Bioaccessibility and health risk assessment of hydrophobic organic pollutants in soils from four typical industrial contaminated sites in China.

There have been reports of potential health risks for people from hydrophobic organic pollutants, such as polycyclic aromatic hydrocarbons (PAHs), polychlorinated hydrocarbons (PCHs), and organophosphate flame retardants (OPFRs). When a contaminated site is used for residential housing or public utility and recreation areas, the soil-bound organic pollutants might pose a threat to human health. In this study, we investigated the contamination profiles and potential risks to human health of 15 PAHs, 6 PCHs, and 12 OPFRs in soils from four contaminated sites in China. We used an in vitro method to determine the oral bioaccessibility of soil pollutants. Total PAHs were found at concentrations ranging from 26.4 ng/g to 987 ng/g. PCHs (0.27‒14.3 ng/g) and OPFRs (6.30‒310 ng/g) were detected, but at low levels compared to earlier reports. The levels of PAHs, PCHs, and OPFRs released from contaminated soils into simulated gastrointestinal fluids ranged from 1.74% to 91.0%, 2.51% to 39.6%, and 1.37% to 96.9%, respectively. Based on both spiked and unspiked samples, we found that the oral bioaccessibility of pollutants was correlated with their logKow and molecular weight, and the total organic carbon content and pH of soils. PAHs in 13 out of 38 contaminated soil samples posed potential high risks to children. When considering oral bioaccessibility, nine soils still posed potential risks, while the risks in the remaining soils became negligible. The contribution of this paper is that it corrects the health risk of soil-bound organic pollutants by detecting bioaccessibility in actual soils from different contaminated sites.

Profiles, exposure assessment and expanded screening of PAHs and their derivatives in one petroleum refinery facility of China.

This study investigated environmental distribution and human exposure of polycyclic aromatic hydrocarbons (PAHs) and their derivatives in one Chinese petroleum refinery facility. It was found that, following with high concentrations of 16 EPA PAHs (∑Parent-PAHs) in smelting subarea of studied petroleum refinery facility, total derivatives of PAHs [named as XPAHs, including nitro PAHs (NPAHs), chlorinated PAHs (Cl-PAHs), and brominated PAHs (Br-PAHs)] in gas (mean= 1.57 × 104 ng/m3), total suspended particulate (TSP) (mean= 4.33 × 103 ng/m3) and soil (mean= 4.37 × 103 ng/g) in this subarea had 1.76-6.19 times higher levels than those from other subareas of this facility, surrounding residential areas and reference areas, indicating that petroleum refining processes would lead apparent derivation of PAHs. Especially, compared with those in residential and reference areas, gas samples in the petrochemical areas had higher ∑NPAH/∑PAHs (mean=2.18), but lower ∑Cl-PAH/∑PAHs (mean=1.43 × 10-1) and ∑Br-PAH/∑PAHs ratios (mean=7.49 × 10-2), indicating the richer nitrification of PAHs than chlorination during petrochemical process. The occupational exposure to PAHs and XPAHs in this petroleum refinery facility were 24-343 times higher than non-occupational exposure, and the ILCR (1.04 × 10-4) for petrochemical workers was considered to be potential high risk. Furthermore, one expanded high-resolution screening through GC Orbitrap/MS was performed for soils from petrochemical area, and another 35 PAHs were found, including alkyl-PAHs, phenyl-PAHs and other species, indicating that profiles and risks of PAHs analogs in petrochemical areas deserve further expanded investigation.

Carbonyl-amine condensation coupled ozonolysis of dipropylamine and styrene: Decay kinetics, reaction mechanism, secondary organic aerosol formation and cytotoxicity.

Oxidation of organic amines (OAs) or aromatic hydrocarbons (AHs) produces carbonyls, which further react with OAs to form carbonyl-amine condensation products, threatening environmental quality and human health. However, there is still a lack of systematic understanding of the carbonyl-amine condensation reaction processes of OAs or between OAs and AHs, and subsequent environmental health impact. This work systematically investigated the carbonyl-amine condensation coupled ozonolysis kinetics, reaction mechanism, secondary organic aerosol (SOA) formation and cytotoxicity from the mixture of dipropylamine (DPA) and styrene (STY) by a combined method of product mass spectrometry identification, particle property analysis and cell exposure evaluation. The results from ozonolysis of DPA and STY mixture revealed that STY inhibited the ozonolysis of DPA to different degrees to accelerate its own decay rate. The barycenter of carbonyl-amine condensation reactions was shifted from inside of DPA to between DPA and STY, which accelerated STY ozonolysis, but slowed down DPA ozonolysis. For the first time, ozonolysis of DPA and STY mixture to complex carbonyl-amine condensation products through the reactions of DPA with its carbonyl products, DPA with STY's carbonyl products and DPA's bond breakage product with STY's carbonyl products was confirmed. These condensation products significantly contributed to the formation and growth of SOA. The SOA containing particulate carbonyl-amine condensation products showed definite cytotoxicity. These findings are helpful to deeply and comprehensively understand the transformation, fate and environmental health effects of mixed organics in atmospheric environment.

Estimation of gaseous polycyclic aromatic hydrocarbons (PAHs) and characteristics of atmospheric PAHs at a traffic site in Kanazawa, Japan.

Size-fractionated particulate matter (PM2.5 and PM>2.5) was collected at a traffic site in Kanazawa, Japan in a seasonal sampling work in 2020. Nine polycyclic aromatic hydrocarbons (4- to 6-ring PAHs) were determined in fine and coarse particles. The gas/particle partitioning coefficients (Kp) of the PAHs were calculated from the supercooled liquid vapour pressure and octanol-air partitioning coefficient based on the relationships obtained in previous traffic pollution-related studies. Gaseous PAHs were estimated by Kp and the concentrations of PM and particulate PAHs. The concentrations of total PAHs were 32.5, 320.1 and 5646.2 pg/m3 in the PM>2.5, PM2.5 and gas phases, respectively. Significant seasonal trends in PAHs were observed (particle phase: lowest in summer, gas phase: lowest in spring, particle and gas phase: lowest in spring). Compared to 2019, the total PAH concentrations (in particles) decreased in 2020, especially in spring and summer, which might be due to reduced traffic trips during the COVID-19 outbreak. The incremental lifetime cancer risk (ILCR) calculated from the toxic equivalent concentrations relative to benzo[a]pyrene (BaPeq) was lower than the acceptable limit issued by the US Environmental Protection Agency, indicating a low cancer risk in long-term exposure to current PAH levels. It is notable that gaseous PAHs considerably contributed to BaPeq and ILCR (over 50%), which highlighted the significance of gaseous PAH monitoring for public health protection. This low-cost estimation method for gaseous PAHs can be expected to reliably and conveniently obtain PAH concentrations as a surrogate for traditional sampling in the future work.

Preparation of Large Perphenylbiaryls: Can Intermolecular Coupling Compete with Intramolecular Cyclization of Precursors?

The highly substituted naphthalenes 1,2,3,4,5,6,7-heptaphenylnaphthalene (13), 2,3,4,5,6,7,8-heptaphenyl-1-naphthol (12), 1-bromo-2,3,4,5,6,7,8-heptaphenylnaphthalene (4), and 1-(phenylethynyl)-2,3,4,5,6,7,8-heptaphenylnaphthalene (5) were prepared by a variety of methods, and all but 5 were crystallographically characterized.  The attempted Ullmann coupling of 4 to give tetradecaphenyl-1,1'-binaphthyl (3), at both 270 °C and 350 °C, yielded instead 1,2,3,4,5,6-hexaphenylfluoranthene (17) via an intramolecular cyclization reaction.  When the alkyne 5 was heated with tetracyclone (6) at 350 °C, 1-(pentaphenylphenyl)-2,3,4,5,6,7,8-heptaphenylnaphthalene (7) was formed in 3% yield.  However, greater amounts of 5,6,7,8,9,14-hexaphenyldibenzo[a,e]pyrene (20, 11%) and 1,2,3,4,5,6,7-heptaphenylfluoranthene (21, 11%) were produced, the former by intramolecular cyclization and dehydrogenation of 5 and the latter by an intramolecular Diels-Alder reaction of 5 followed by extrusion of acetylene.  The X-ray structure of 7 shows it to be an exceptionally crowded biaryl, and the X-ray structure of 20 shows it to be a saddle shaped polycyclic aromatic hydrocarbon.

Mechanistic Insights into the Evolution of Graphitic Carbon from Sulfur Containing Polar Aromatic Feedstock.

In the realm of carbon fiber research, a variety of structural configurations is noted, comprising crystalline, noncrystalline, and semicrystalline forms. Recent investigations into this domain have revealed an array of intriguing phases of carbon, among which amorphous graphite is the most notable for its unique mechanical, thermal, and electrical properties that arise from its inherent topological disorders. In this study, we utilized the ReaxFF molecular dynamics (MD) simulations to investigate the carbonization and graphitization processes involved in the production of amorphous graphite from benzothiophene, a sulfur-containing polar aromatic precursor. We developed C/H/S ReaxFF force field parameters to describe the high-temperature chemistry of benzothiophene. Our investigation reveals the reaction mechanisms, providing critical insights into the underlying chemical processes toward the formation of amorphous graphite and the structural characteristics of the end products. The formation of volatile gaseous molecules and their continuous elimination led to the development of noncontinuous layered graphite structures analogous to amorphous graphite consisting of pentagons, hexagons, and heptagons. These findings offer unprecedented insights into the carbonization and graphitization processes of sulfur-containing heavy-end aromatic feedstock. This knowledge lays the groundwork for advancing synthesis methods and developing amorphous graphite materials with specific properties.

Transcriptomic data sets for Novosphingobium aromaticivorans grown with the ß-5-linked aromatic dimer dehydrodiconiferyl alcohol and the related G-aromatic monomers vanillin and ferulic acid.

The transcriptomes of a 2-pyrone-4,6-dicarboxylic acid-producing strain of Novosphingobium aromaticivorans DSM12444 were determined when grown in minimal medium containing glucose alone or glucose plus vanillin, ferulic acid, or the ß-5-linked aromatic dimer dehydrodiconiferyl alcohol as carbon sources. Here, we present the RNA-sequencing data we obtained.

Development of a green microextraction procedure for determining polyaromatic hydrocarbons in electronic equipment plastics.

The global proliferation of electronic devices, driven by technological advancements, has led to the release of organic pollutants from the plastic components of these devices, particularly in indoor environments. Among these pollutants, polycyclic aromatic hydrocarbons (PAHs), which are emitted into the air from plastic components, play a critical role in the field of indoor environment pollution. Consequently, effectively monitoring the PAH content in plastics used in electronic equipment is crucial for preventing indoor contamination. In this study we aimed to develop a fast, inexpensive, easy, and environmentally friendly analysis method for determining PAH content in plastic equipment. A dispersive liquid liquid microextraction (DLLME) combined with solidified organic drop (SFO) microextraction technique was developed. Considering the eleven number of parameters that can affect the signal in the DLLME-SFO method, Plackett Burmann's design was applied to select the most three impactful parameters for 18 PAH species. A Box-Behnken experimental design was also applied to optimize the identified parameters. The optimal conditions for the most influential parameters such as solvent type, pH, and the sample weight were identified as 1-dodecanol, 12 and 0.24 g, respectively. The proposed method was validated under these optimized conditions, yielding low detection limits ranging from 0.004 to 0.11 ng mL-1. The calibration curves were linear with correlation coefficients above 0.98 and relative standard deviation (RSD) values ranging from 2.4% to 20%. This method was successfully applied to analyze PAH content in the plastic components of electronic devices. The extraction technique developed in this study is a newly developed technique and has not been previously used to analyze organic pollutants that may be present in electronic equipment plastic.

Association between aromatic amines and serum neurofilament light chain as a biomarker of neural damage: a cross-sectional study from NHANES.

Background: Aromatic amines (AAs) are a group of compounds widely found in chemical industry, tobacco smoke, and during food processing, with established carcinogenic properties. To date, there have been no reports on the potential neurotoxic effects of adult exposure to AAs. Serum neurofilament light chain (sNfL) is a protein released into the bloodstream following nerve axon injury and has been validated as a reliable biomarker for various neurological diseases. However, there has been no research to investigate the relationship between AAs exposure and sNfL. Methods: In this study, we selected adults (aged ≥20 years) with data on both AAs and sNfL from the National Health and Nutrition Examination Survey (NHANES) conducted in 2013-2014. We used multivariable linear regression models to explore the correlation between urinary AAs and sNfL. Results: In total, 510 adult participants with an average age of 43.58 ± 14.74 years were included in the study. Our findings indicate that, based on univariate linear regression and between-group comparative analyses, 1-Aminonaphthalene (1-AN), 2-Aminonaphthalene (2-AN), 4-Aminobiphenyl (4-AN) and o-Anisidine (o-ANI) showed a positive correlation with serum neurofilament light chain (P < 0.05). However, multiple linear regression analysis revealed that only 2-AN exhibited a positive correlation with serum neurofilament light chain (P < 0.05), while the correlations of other compounds with serum neurofilament light chain became non-significant. Conclusion: Although our cross-sectional study fails to establish causal relationships or determine clinical significance, the findings indicate a potential association between adult exposure to AAs, notably 2-AN, and nerve damage. Consequently, further research is needed to explore the connection between AAs exposure, sNfL, and neurological conditions in adults.

A critical examination of human data for the biological activity of phenolic acids and their phase-2 conjugates derived from dietary (poly)phenols, phenylalanine, tyrosine and catecholamines.

Free or conjugated aromatic/phenolic acids arise from the diet, endogenous metabolism of catecholamines (adrenaline, noradrenaline, dopamine), protein (phenylalanine, tyrosine), pharmaceuticals (aspirin, metaprolol) plus gut microbiota metabolism of dietary (poly)phenols and undigested protein. Quantitative data obtained with authentic calibrants for 112 aromatic/phenolic acids including phase-2 conjugates in human plasma, urine, ileal fluid, feces and tissues have been collated and mean/median values compared with in vitro bioactivity data in cultured cells. Ca 30% of publications report bioactivity at ≤1 µmol/L. With support from clinical studies, it appears that the greatest benefit might be produced in vascular tissues by C6-C3 metabolites, including some of gut microbiota origin and some phase-2 conjugates, 15 of which are 3',4'-disubstituted with multiple sources including caffeic acid and hesperetin, plus one unsubstituted and two mono-substituted examples which can originate from protein. There is an unexamined potential for synergy. Free-living and washout plasma data are scarce. Some metabolites have been overlooked, notably phenyl-lactic, phenyl-hydracrylic and phenyl-propanoic acids, especially those from amino acids plus glycine, hydroxy-glycine and glutamine conjugates. Phenolic acids and conjugates from multiple sources exhibit biological activities, some of which are likely relevant in vivo and link to biomarkers of health. Further targeted studies are justified.

Spatiotemporal variation of polycyclic aromatic hydrocarbons in Tibetan lake sediment cores reveals the influence of forest fires.

Despite declining anthropogenic emissions of polycyclic aromatic hydrocarbons (PAHs) due to global control strategies, forest fire emissions have been increasing, significantly affecting PAH dynamics in global sinks. This study investigated the spatiotemporal variations of sedimentary PAHs in three Tibetan lakes-Yiong Tso, Yamdrok Yumtso, and Urru Tso-to determine the influence of forest fires on PAH levels and historical trends. Yiong Tso Lake, located in a fire-affected watershed, exhibited the highest PAH concentrations (average of 43.4 ±â€¯25.7 ng/g) with significant fluctuations since the 1920s, peaking in the 1960s (46.3 ng/g) and 1980s (91.3 ng/g), corresponding to periods of intense forest fires. This pattern aligned with source contribution estimates using the modified Cohen's d (mcd), indicating the dominance of forest fires as a PAH source until the 1990s. PAH concentrations decreased with increasing distance from the southeastern Tibetan Forest, as observed in Yamdrok Yumtso (average of 36.1 ±â€¯19.9 ng/g) and Urru Tso (average of 16.4 ±â€¯6.9 ng/g). Temporal variations in PAH concentrations and mcd values from these lakes also reflected a response to forest fires during the 1960s, suggesting a widespread influence of forest-fire-derived PAHs across the plateau. The impact of forest fires on sedimentary PAHs was expected to persist for decades, with an estimated half-life of approximately 11-12 years. These findings highlight significant emissions of PAHs from forest fires in the Tibetan Plateau, potentially transforming regional PAH dynamics and influencing global cycling.

Redox-Induced Aromatic Substitution: A Study on Guanidino-Functionalized Aromatics.

Aromatic substitution of redox-active aromatic compounds could be initiated by a preceding redox step. We report on the different reaction pathways of such redox-induced substitution (RIAS) reactions between a redox-active guanidino-functionalized aromatic molecule (GFA) and an amine or guanidine. Oxidation of the GFA leads to an umpolung of the guanidine from a nucleophile to an electrophile and thereby enables addition of the amine or guanidine. Several examples are given, demonstrating the use of redox substitution in synthetic chemistry, e.g. for the convenient synthesis of novel N-heteropolycyclic molecules and unsymmetrically-substituted aromatics.

A direct immersion-solid-phase microextraction method for the automated determination of 3- to 6-ring polycyclic aromatic hydrocarbons in saliva by gas-chromatography-tandem mass spectrometry.

This work presents a novel method for the analysis of polycyclic aromatic hydrocarbons (PAHs) in saliva samples using solid phase microextraction (SPME) coupled with gas chromatography-triple quadrupole mass spectrometry (GC-QqQ-MS). The protocol utilizes the latest commercially available overcoated fiber (PDMS/DVB/PDMS) for direct immersion extraction of the target analytes, enabling the determination of thirteen PAHs, including low-volatile compounds. The SPME extraction method was optimized using a central composite design (CCD). The evaluation of the fiber coating's robustness over time demonstrated excellent extraction performance with no significant degradation. The validation procedure confirmed good performance for all parameters, with LOQ values (100 ng/L for ten analytes and 500 ng/L for three analytes) comparable to other chromatographic methods. The environmental impact of the protocol was objectively assessed using two recently proposed metrics: the Green Analytical Procedure Index (GAPI) and the Analytical Greenness metric for sample preparation (AGREEprep). Both metrics indicated good overall environmental friendliness, with AGREEprep providing a satisfactory comprehensive score despite the use of highly impactful instrumentation. These characteristics make the developed method suitable for routine analysis in environmental and epidemiological monitoring.

The development of rapid immunoassays for the urinary analysis of 1-hydroxypyrene glucuronide facilitate both laboratory and on-site polycyclic aromatic hydrocarbon biomonitoring.

Polycylic Aromatic Hydrocarbons (PAHs) are produced during the incomplete burning of organic materials. PAH sources include vehicle exhaust, tobacco smoke and waste incineration. Environmental and occupational exposures to PAHs are known to occur. Cancer is a significant endpoint of PAH exposure and several occupations associated with high PAH exposure have been classified by IARC as carcinogenic to humans (Group 1). Pyrene is a common component of PAH mixtures and metabolism of pyrene leads to the excretion of 1-hydroxypyrene glucuronide (1-OHPyrG) in urine. Laboratory measurement of urinary 1-OHPyrG is employed in occupational and environmental biomonitoring programmes. The production of an anti-1-OHPyrG monoclonal antibody would allow the development of a PAH biomonitoring ELISA facilitating large scale laboratory screening and routine testing. The development of a lateral flow immunoassay and the production of a field test (point of use test) would greatly increase the value of biomonitoring. A novel Lateral Flow has been developed which employs an anti-1-OHPyrG sheep monoclonal antibody (Mab) to capture the PAH metabolite. The captured metabolite is visualised through a second Mab raised against the Mab-1-OHPyrG immune complex. This sandwich assay provides a positive correlation between the assay signal and biomarker concentration. A Smartphone camera allows signal measurement and a carefully considered 'app' provides result interpretation and data analysis. Results are provided in an exposed/not-exposed format. Performance of the lateral flow was confirmed through a comparative study and field trial. The development of a lateral flow test provides "real-time" analysis to occupational health professionals. On-site screening allows the immediate confirmation of safe working practice, provides immediate reassurance to those involved in potentially hazardous activities and greatly increases the efficacy of biomonitoring.