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1.
Sci Rep ; 14(1): 10561, 2024 05 08.
Article in English | MEDLINE | ID: mdl-38719884

ABSTRACT

This study focuses on understanding the structural and molecular changes in lipid membranes under the influence of six halogenated flavonoid derivatives differing in the number and position of substitution of chlorine and bromine atoms (D1-D6). Utilizing various analytical techniques, including fluorometric methods, dynamic light scattering (DLS), attenuated Fourier transform infrared spectroscopy (ATR- FTIR), and FT-Raman spectroscopy, the research aims to elucidate the mechanisms underlying the interaction of flavonoids with cell membranes. Additionally, the study includes in silico analyses to explore the physicochemical properties of these compounds and their potential pharmaceutical applications, along with toxicity studies to assess their effects on cancer, normal, and red blood cells. Our study showed the ability of halogenated derivatives to interact mostly with the outer part of the membrane, especially in the lipid heads region however, some of them were able to penetrate deeper into the membrane and affect the fluidity of hydrocarbon chains. The potential to reduce cancer cell viability, the lack of toxicity towards erythrocytes, and the favourable physicochemical and pharmacokinetic properties suggest these halogenated flavonoids potential candidates for exploring their potential for medical use.


Subject(s)
Flavonoids , Membrane Lipids , Flavonoids/chemistry , Flavonoids/pharmacology , Flavonoids/metabolism , Humans , Membrane Lipids/metabolism , Membrane Lipids/chemistry , Cell Membrane/metabolism , Halogenation , Cytotoxins/chemistry , Cytotoxins/pharmacology , Cytotoxins/metabolism , Erythrocytes/drug effects , Erythrocytes/metabolism , Cell Survival/drug effects , Spectrum Analysis, Raman , Spectroscopy, Fourier Transform Infrared , Antineoplastic Agents/pharmacology , Antineoplastic Agents/chemistry , Antineoplastic Agents/metabolism , Cell Line, Tumor
2.
Int J Mol Sci ; 25(9)2024 Apr 23.
Article in English | MEDLINE | ID: mdl-38731806

ABSTRACT

This study reveals a new non-covalent interaction called a π-hole halogen bond, which is directional and potentially non-linear compared to its sister analog (σ-hole halogen bond). A π-hole is shown here to be observed on the surface of halogen in halogenated molecules, which can be tempered to display the aptness to form a π-hole halogen bond with a series of electron density-rich sites (Lewis bases) hosted individually by 32 other partner molecules. The [MP2/aug-cc-pVTZ] level characteristics of the π-hole halogen bonds in 33 binary complexes obtained from the charge density approaches (quantum theory of intramolecular atoms, molecular electrostatic surface potential, independent gradient model (IGM-δginter)), intermolecular geometries and energies, and second-order hyperconjugative charge transfer analyses are discussed, which are similar to other non-covalent interactions. That a π-hole can be observed on halogen in halogenated molecules is substantiated by experimentally reported crystals documented in the Cambridge Crystal Structure Database. The importance of the π-hole halogen bond in the design and growth of chemical systems in synthetic chemistry, crystallography, and crystal engineering is yet to be fully explicated.


Subject(s)
Halogens , Static Electricity , Halogens/chemistry , Models, Molecular , Quantum Theory , Electrons , Thermodynamics , Lewis Bases/chemistry , Halogenation
3.
Int J Mol Sci ; 25(9)2024 Apr 26.
Article in English | MEDLINE | ID: mdl-38731937

ABSTRACT

Due to the favorable features obtained through the incorporation of fluorine atom(s), fluorinated drugs are a group with emerging pharmaceutical importance. As their commercial availability is still very limited, to expand the range of possible candidates, new fluorinated tryptophan analogs were synthesized. Control of enantiopurity during the synthesis procedure requires that highly efficient enantioseparation methods be available. In this work, the enantioseparation of seven fluorinated tryptophans and tryptophan was studied and compared systematically to (i) develop analytical methods for enantioselective separations and (ii) explore the chromatographic features of the fluorotrytophans. For enantioresolution, macrocyclic glycopeptide-based selectors linked to core-shell particles were utilized, applying liquid chromatography-based methods. Application of the polar-ionic mode resulted in asymmetric and broadened peaks, while reversed-phase conditions, together with mobile-phase additives, resulted in baseline separation for all studied fluorinated tryptophans. The marked differences observed between the methanol and acetonitrile-containing eluent systems can be explained by the different solvation abilities of the bulk solvents of the applied mobile phases. Among the studied chiral selectors, teicoplanin and teicoplanin aglycone were found to work effectively. Under optimized conditions, baseline separations were achieved within 6 min. Ionic interactions were semi-quantitatively characterized and found to not influence enantiorecognition. Interestingly, fluorination of the analytes does not lead to marked changes in the chromatographic characteristics of the methanol-containing eluents, while larger differences were noticed when the polar but aprotic acetonitrile was applied. Experiments conducted on the influence of the separation temperature indicated that the separations are enthalpically driven, with only one exception. Enantiomeric elution order was found to be constant on both teicoplanin and teicoplanin aglycone-based chiral stationary phases (L < D) under all applied chromatographic conditions.


Subject(s)
Glycopeptides , Halogenation , Teicoplanin , Tryptophan , Tryptophan/chemistry , Tryptophan/analogs & derivatives , Glycopeptides/chemistry , Stereoisomerism , Teicoplanin/chemistry , Teicoplanin/analogs & derivatives , Chromatography, Liquid/methods , Chromatography, High Pressure Liquid/methods , Macrocyclic Compounds/chemistry
4.
Anal Chem ; 96(19): 7386-7393, 2024 May 14.
Article in English | MEDLINE | ID: mdl-38698660

ABSTRACT

Covalent labeling in combination with mass spectrometry is a powerful approach used in structural biology to study protein structures, interactions, and dynamics. Recently, the toolbox of covalent labeling techniques has been expanded with fast fluoroalkylation of proteins (FFAP). FFAP is a novel radical labeling method that utilizes fluoroalkyl radicals generated from hypervalent Togni reagents for targeting aromatic residues. This report further demonstrates the benefits of FFAP as a new method for structural characterization of therapeutic antibodies and interaction interfaces of antigen-antibody complexes. The results obtained from human trastuzumab and its complex with human epidermal growth factor receptor 2 (HER2) correlate well with previously published structural data and demonstrate the potential of FFAP in structural biology.


Subject(s)
Epitope Mapping , Receptor, ErbB-2 , Trastuzumab , Humans , Epitope Mapping/methods , Receptor, ErbB-2/chemistry , Receptor, ErbB-2/immunology , Trastuzumab/chemistry , Alkylation , Antibodies, Monoclonal/chemistry , Antibodies, Monoclonal/immunology , Halogenation , Protein Footprinting/methods , Antigen-Antibody Complex/chemistry
5.
Environ Sci Technol ; 58(18): 8065-8075, 2024 May 07.
Article in English | MEDLINE | ID: mdl-38597221

ABSTRACT

We report a previously unrecognized but efficient reductive degradation pathway in peroxydisulfate (PDS)-driven soil remediation. With supplements of naturally occurring low-molecular-weight organic acids (LMWOAs) in anaerobic biochar-activated PDS systems, degradation rates of 12 γ-hexachlorocyclohexanes (HCH)-spiked soils boosted from 40% without LMWOAs to a maximum of 99% with 1 mM malic acid. Structural analysis revealed that an increase in α-hydroxyl groups and a diminution in pKa1 values of LMWOAs facilitated the formation of reductive carboxyl anion radicals (COO•-) via electrophilic attack by SO4•-/•OH. Furthermore, degradation kinetics were strongly correlated with soil organic matter (SOM) contents than iron minerals. Combining a newly developed in situ fluorescence detector of reductive radicals with quenching experiments, we showed that for soils with high, medium, and low SOM contents, dominant reactive species switched from singlet oxygen/semiquinone radicals to SO4•-/•OH and then to COO•- (contribution increased from 30.8 to 66.7%), yielding superior HCH degradation. Validation experiments using SOM model compounds highlighted critical roles of redox-active moieties, such as phenolic - OH and quinones, in radical formation and conversion. Our study provides insights into environmental behaviors related to radical activation of persulfate in a broader soil horizon and inspiration for more advanced reduction technologies.


Subject(s)
Soil , Soil/chemistry , Free Radicals/chemistry , Soil Pollutants/chemistry , Oxidation-Reduction , Halogenation
6.
J Hazard Mater ; 470: 134217, 2024 May 15.
Article in English | MEDLINE | ID: mdl-38583197

ABSTRACT

Tetrabromobisphenol A (TBBPA), a common brominated flame retardant and a notorious pollutant in anaerobic environments, resists aerobic degradation but can undergo reductive dehalogenation to produce bisphenol A (BPA), an endocrine disruptor. Conversely, BPA is resistant to anaerobic biodegradation but susceptible to aerobic degradation. Microbial degradation of TBBPA via anoxic/oxic processes is scarcely documented. We established an anaerobic microcosm for TBBPA dehalogenation to BPA facilitated by humin. Dehalobacter species increased with a growth yield of 1.5 × 108 cells per µmol Br- released, suggesting their role in TBBPA dehalogenation. We innovatively achieved complete and sustainable biodegradation of TBBPA in sand/soil columns columns, synergizing TBBPA reductive dehalogenation by anaerobic functional microbiota and BPA aerobic oxidation by Sphingomonas sp. strain TTNP3. Over 42 days, 95.11 % of the injected TBBPA in three batches was debrominated to BPA. Following injection of strain TTNP3 cells, 85.57 % of BPA was aerobically degraded. Aerobic BPA degradation column experiments also indicated that aeration and cell colonization significantly increased degradation rates. This treatment strategy provides valuable technical insights for complete TBBPA biodegradation and analogous contaminants.


Subject(s)
Biodegradation, Environmental , Flame Retardants , Oxidation-Reduction , Phenols , Polybrominated Biphenyls , Polybrominated Biphenyls/metabolism , Polybrominated Biphenyls/chemistry , Anaerobiosis , Aerobiosis , Phenols/metabolism , Flame Retardants/metabolism , Benzhydryl Compounds/metabolism , Sphingomonas/metabolism , Halogenation , Soil Pollutants/metabolism
7.
J Med Chem ; 67(8): 6207-6217, 2024 Apr 25.
Article in English | MEDLINE | ID: mdl-38607332

ABSTRACT

Sigma-1 receptor (σ1R) is an intracellular protein implicated in a spectrum of neurodegenerative conditions, notably Alzheimer's disease (AD). Positron emission tomography (PET) imaging of brain σ1R could provide a powerful tool for better understanding the underlying pathomechanism of σ1R in AD. In this study, we successfully developed a 18F-labeled σ1R radiotracer [18F]CNY-05 via an innovative ruthenium (Ru)-mediated 18F-deoxyfluorination method. [18F]CNY-05 exhibited preferable brain uptake, high specific binding, and slightly reversible pharmacokinetics within the PET scanning time window. PET imaging of [18F]CNY-05 in nonhuman primates (NHP) indicated brain permeability, metabolic stability, and safety. Moreover, autoradiography and PET studies of [18F]CNY-05 in the AD mouse model found a significantly decreased brain uptake compared to that in wild-type mice. Collectively, we have provided a novel 18F-radiolabeled σ1R PET probe, which enables visualizing brain σ1R in health and neurological diseases.


Subject(s)
Alzheimer Disease , Brain , Fluorine Radioisotopes , Positron-Emission Tomography , Radiopharmaceuticals , Receptors, sigma , Sigma-1 Receptor , Receptors, sigma/metabolism , Animals , Alzheimer Disease/diagnostic imaging , Alzheimer Disease/metabolism , Brain/metabolism , Brain/diagnostic imaging , Fluorine Radioisotopes/chemistry , Positron-Emission Tomography/methods , Mice , Radiopharmaceuticals/chemistry , Radiopharmaceuticals/pharmacokinetics , Radiopharmaceuticals/chemical synthesis , Male , Molecular Imaging/methods , Halogenation , Tissue Distribution , Humans
8.
Methods Enzymol ; 696: 231-247, 2024.
Article in English | MEDLINE | ID: mdl-38658081

ABSTRACT

Nonheme iron enzymes stand out as one of the most versatile biocatalysts for molecular functionalization. They facilitate a wide array of chemical transformations within biological processes, including hydroxylation, chlorination, epimerization, desaturation, cyclization, and more. Beyond their native biological functions, these enzymes possess substantial potential as powerful biocatalytic platforms for achieving abiological metal-catalyzed reactions, owing to their functional and structural diversity and high evolvability. To this end, our group has recently engineered a series of nonheme iron enzymes to employ non-natural radical-relay mechanisms for abiological radical transformations not previously known in biology. Notably, we have demonstrated that a nonheme iron enzyme, (S)-2-hydroxypropylphosphonate epoxidase from Streptomyces viridochromogenes (SvHppE), can be repurposed into an efficient and selective biocatalyst for radical fluorine transfer reactions. This marks the first known instance of a redox enzymatic process for C(sp3)F bond formation. This chapter outlines the detailed experimental protocol for engineering SvHPPE for fluorination reactions. Furthermore, the provided protocol could serve as a general guideline that might facilitate other engineering endeavors targeting nonheme iron enzymes for novel catalytic functions.


Subject(s)
Biocatalysis , Fluorine , Halogenation , Protein Engineering , Streptomyces , Fluorine/chemistry , Protein Engineering/methods , Streptomyces/enzymology , Streptomyces/genetics , Oxidoreductases/metabolism , Oxidoreductases/genetics , Oxidoreductases/chemistry , Oxidation-Reduction , Nonheme Iron Proteins/chemistry , Nonheme Iron Proteins/metabolism , Nonheme Iron Proteins/genetics , Bacterial Proteins/genetics , Bacterial Proteins/metabolism , Bacterial Proteins/chemistry
9.
Methods Enzymol ; 696: 199-229, 2024.
Article in English | MEDLINE | ID: mdl-38658080

ABSTRACT

Fluorine (F) is an important element in the synthesis of molecules broadly used in medicine, agriculture, and materials. F addition to organic structures represents a unique strategy for tuning molecular properties, yet this atom is rarely found in Nature and approaches to produce fluorometabolites (such as fluorinated amino acids, key building blocks for synthesis) are relatively scarce. This chapter discusses the use of L-threonine aldolase enzymes (LTAs), a class of enzymes that catalyze reversible aldol addition to the α-carbon of glycine. The C-C bond formation ability of LTAs, together with their known substrate promiscuity, make them ideal for in vitro F biocatalysis. Here, we describe protocols to harness the activity of the low-specificity LTAs isolated from Escherichia coli and Pseudomonas putida on 2-fluoroacetaldehyde to efficiently synthesize 4-fluoro-L-threonine in vitro. This chapter also provides a comprehensive account of experimental protocols to implement these activities in vivo. These methods are illustrative and can be adapted to produce other fluorometabolites of interest.


Subject(s)
Escherichia coli , Halogenation , Pseudomonas putida , Substrate Specificity , Escherichia coli/enzymology , Escherichia coli/genetics , Pseudomonas putida/enzymology , Biocatalysis , Amino Acids/chemistry , Glycine Hydroxymethyltransferase/metabolism , Glycine Hydroxymethyltransferase/chemistry , Glycine Hydroxymethyltransferase/genetics , Threonine/chemistry , Threonine/metabolism , Threonine/analogs & derivatives , Fluorine/chemistry , Aldehydes/chemistry , Aldehydes/metabolism
10.
Methods Enzymol ; 696: 287-320, 2024.
Article in English | MEDLINE | ID: mdl-38658084

ABSTRACT

Acidimicrobium sp. strain A6 is a recently discovered autotrophic bacterium that is capable of oxidizing ammonium while reducing ferric iron and is relatively common in acidic iron-rich soils. The genome of Acidimicrobium sp. strain A6 contains sequences for several reductive dehalogenases, including a gene for a previously unreported reductive dehalogenase, rdhA. Incubations of Acidimicrobium sp. strain A6 in the presence of perfluorinated substances, such as PFOA (perfluorooctanoic acid, C8HF15O2) or PFOS (perfluorooctane sulfonic acid, C8HF17O3S), have shown that fluoride, as well as shorter carbon chain PFAAs (perfluoroalkyl acids), are being produced, and the rdhA gene is expressed during these incubations. Results from initial gene knockout experiments indicate that the enzyme associated with the rdhA gene plays a key role in the PFAS defluorination by Acidimicrobium sp. strain A6. Experiments focusing on the defluorination kinetics by Acidimicrobium sp. strain A6 show that the defluorination kinetics are proportional to the amount of ammonium oxidized. To explore potential applications for PFAS bioremediation, PFAS-contaminated biosolids were augmented with Fe(III) and Acidimicrobium sp. strain A6, resulting in PFAS degradation. Since the high demand of Fe(III) makes growing Acidimicrobium sp. strain A6 in conventional rectors challenging, and since Acidimicrobium sp. strain A6 was shown to be electrogenic, it was grown in the absence of Fe(III) in microbial electrolysis cells, where it did oxidize ammonium and degraded PFAS.


Subject(s)
Biodegradation, Environmental , Fluorocarbons , Fluorocarbons/metabolism , Fluorocarbons/chemistry , Bacterial Proteins/metabolism , Bacterial Proteins/genetics , Caprylates/metabolism , Halogenation , Alkanesulfonic Acids/metabolism , Alkanesulfonic Acids/chemistry , Oxidation-Reduction
11.
Methods Enzymol ; 696: 321-338, 2024.
Article in English | MEDLINE | ID: mdl-38658086

ABSTRACT

Research on microbial defluorination is largely centred on controlled experiments using axenic or well defined microbial inocula. These approaches serve a relevant purpose in the field, offering fundamental biochemical and mechanistic insights on the intricacies of biological defluorination. However, they fail to account for the effective contribution of environmental microbial communities in the recycling of fluoroorganic pollutants, a highly relevant perspective from an environmental risk assessment standpoint, while also missing an important outlook on how community-wide dynamics can leverage the breakdown of C─F bonds in these recalcitrant compounds. With that in mind, this chapter provides experimental and methodological insights on the study of microbial defluorination in wild environmental communities, using this critical catabolic step as the de facto endpoint to evolve, select and cultivate microorganisms with improved defluorination performances.


Subject(s)
Biodegradation, Environmental , Bacteria/metabolism , Bacteria/genetics , Environmental Pollutants/metabolism , Halogenation , Environmental Microbiology , Microbiota , Fluorine/metabolism , Fluorine/chemistry
12.
Methods Enzymol ; 696: 341-354, 2024.
Article in English | MEDLINE | ID: mdl-38658087

ABSTRACT

The site-specific encoding of noncanonical amino acids allows for the introduction of rationalized chemistry into a target protein. Of the methods that enable this technology, evolved tRNA and synthetase pairs offer the potential for expanded protein production and purification. Such an approach combines the versatility of solid-phase peptide synthesis with the scalable features of recombinant protein production. We describe the large scale production and purification of eukaryotic proteins bearing fluorinated phenylalanine in mammalian suspension cell preparations. Downstream applications of this approach include scalable recombinant protein preparation for ligand binding assays with small molecules and ligands, protein structure determination, and protein stability assays.


Subject(s)
Halogenation , Recombinant Proteins , Recombinant Proteins/isolation & purification , Recombinant Proteins/genetics , Recombinant Proteins/metabolism , Recombinant Proteins/chemistry , Animals , Humans , Phenylalanine/chemistry , Phenylalanine/isolation & purification , Phenylalanine/metabolism , Cell Culture Techniques/methods , HEK293 Cells
13.
Methods Enzymol ; 696: 251-285, 2024.
Article in English | MEDLINE | ID: mdl-38658083

ABSTRACT

Some species of the genus Cunninghamella (C. elegans, C. echinulata and C. blaskesleeana) produce the same phase I and phase II metabolites when incubated with xenobiotics as mammals, and thus are considered microbial models of mammalian metabolism. This had made these fungi attractive for metabolism studies with drugs, pesticides and environmental pollutants. As a substantial proportion of pharmaceuticals and agrochemicals are fluorinated, their biotransformation has been studied in Cunninghamella fungi and C. elegans in particular. This article details the methods employed for cultivating the fungi in planktonic and biofilm cultures, and extraction and analysis of fluorinated metabolites. Furthermore, protocols for the heterologous expression of Cunninghamella cytochromes P450 (CYPs), which are the enzymes associated with phase I metabolism, are described.


Subject(s)
Biotransformation , Cunninghamella , Cytochrome P-450 Enzyme System , Xenobiotics , Cunninghamella/metabolism , Xenobiotics/metabolism , Cytochrome P-450 Enzyme System/metabolism , Halogenation , Biofilms , Pharmaceutical Preparations/metabolism , Animals
14.
Methods Enzymol ; 696: 65-83, 2024.
Article in English | MEDLINE | ID: mdl-38658089

ABSTRACT

There is intense interest in removing fluorinated compounds from the environment, environments are most efficiently remediated by microbial enzymes, and defluorinating enzymes are readily monitored by fluoride determination. Fluorine is the most electronegative element. Consequently, all mechanisms of enzymatic C-F bond cleavage produce fluoride anion, F-. Therefore, methods for the determination of fluoride are critical for C-F enzymology and apply to any fluorinated organic compounds, including PFAS, or per- and polyfluorinated alkyl substances. The biodegradation of most PFAS chemicals is rare or unknown. Accordingly, identifying new enzymes, or re-engineering the known defluorinases, will require rapid and sensitive methods for measuring fluoride in aqueous media. Most studies currently use ion chromatography or fluoride specific electrodes which are relatively sensitive but low throughput. The methods here describe refashioning a drinking water test to efficiently determine fluoride in enzyme and cell culture reaction mixtures. The method is based on lanthanum alizarin complexone binding of fluoride. Reworking the method to a microtiter well plate format allows detection of as little as 4 nmol of fluoride in 200 µL of assay buffer. The method is amenable to color imaging, spectrophotometric plate reading and automated liquid handling to expedite assays with thousands of enzymes and/or substrates for discovering and improving enzymatic defluorination.


Subject(s)
Fluorides , Fluorides/analysis , Fluorides/metabolism , Drinking Water/analysis , Halogenation , Enzyme Assays/methods , Enzyme Assays/instrumentation
15.
Sci Total Environ ; 927: 172095, 2024 Jun 01.
Article in English | MEDLINE | ID: mdl-38575011

ABSTRACT

This comprehensive investigation highlighted the complex adsorption behaviors of antibiotics onto granular activated carbon (GAC), the effectiveness of this adsorption in reducing bacterial toxicity, and the reduction of antibiotic resistance genes (ARGs) and antibiotic resistant bacteria (ARB) in hospital wastewater (HWW) effluents. Six GACs were characterized for their physicochemical properties, and their ability to adsorb six antibiotics in the background matrix of actual HWW was evaluated. Coconut shell-derived GAC (Co-U), which had the highest hydrophobicity and lowest content of oxygen-containing acidic functional groups, demonstrated the highest adsorption capacities for the tested antibiotics. Bacterial toxicity tests revealed that GACs could eliminate the bacterial toxicity from antibiotic intermediates present in chlorinated HWW. By contrast, the bacterial toxicity could not be removed by GACs in non-chlorinated HWW due to the greater presence of intermediate components identified by LC-MS/MS. The intraparticle diffusion coefficient of antibiotics adsorbed onto Co-U could be calculated by adsorption kinetics derived from the linear driving force model and the homogenous intraparticle diffusion model associated with the linear adsorption isotherms (0-150 µg/L). Meropenem and sulfamethoxazole exhibited the highest adsorption capacities in a single-solute solution compared to penicillin G, ampicillin, cetazidime, and ciprofloxacin. However, the greater adsorption capacities of meropenem and sulfamethoxazole disappeared in mixed-solute solutions, indicating the lowest adsorption competition. GAC can eliminate most ARGs while also promoting the growth of some ARB. Chlorination (free chlorine residues at 0.5 mg Cl2/L) did not significantly affect the overall composition of ARGs and ARB in HWW. However, the accumulation of ARGs and ARB on GAC in fixed bed columns was lower in chlorinated HWW than in non-chlorinated HWW due to an increase in the adsorption of intermediates.


Subject(s)
Anti-Bacterial Agents , Charcoal , Halogenation , Waste Disposal, Fluid , Wastewater , Water Pollutants, Chemical , Charcoal/chemistry , Wastewater/chemistry , Waste Disposal, Fluid/methods , Adsorption , Drug Resistance, Microbial/genetics , Hospitals , Bacteria/drug effects , Drug Resistance, Bacterial/genetics
16.
Molecules ; 29(8)2024 Apr 20.
Article in English | MEDLINE | ID: mdl-38675699

ABSTRACT

In the face of ongoing water pollution challenges, the intricate interplay between dissolved organic matter and disinfectants like chlorine gives rise to potentially harmful disinfection byproducts (DBPs) during water treatment. The exploration of DBP formation originating from amino acids (AA) is a critical focus of global research. Aromatic DBPs, in particular, have garnered considerable attention due to their markedly higher toxicity compared to their aliphatic counterparts. This work seeks to advance the understanding of DBP formation by investigating chlorination disinfection and kinetics using tyrosine (Tyr), phenylalanine (Phe), and tryptophan (Trp) as precursors. Via rigorous experiments, a total of 15 distinct DBPs with accurate molecular structures were successfully identified. The chlorination of all three AAs yielded highly toxic chlorophenylacetonitriles (CPANs), and the disinfectant dosage and pH value of the reaction system potentially influence chlorination kinetics. Notably, Phe exhibited the highest degradation rate compared to Tyr and Trp, at both the CAA:CHOCl ratio of within 1:2 and a wide pH range (6.0 to 9.0). Additionally, a neutral pH environment triggered the maximal reaction rates of the three AAs, while an acidic condition may reduce their reactivity. Overall, this study aims to augment the DBP database and foster a deeper comprehension of the DBP formation and relevant kinetics underlying the chlorination of aromatic AAs.


Subject(s)
Amino Acids, Aromatic , Disinfection , Halogenation , Water Purification , Kinetics , Amino Acids, Aromatic/chemistry , Water Purification/methods , Disinfectants/chemistry , Water Pollutants, Chemical/chemistry , Hydrogen-Ion Concentration
17.
Environ Sci Technol ; 58(17): 7543-7553, 2024 Apr 30.
Article in English | MEDLINE | ID: mdl-38632926

ABSTRACT

Coumarin was detected as one of the most abundant compounds by nontargeted analysis of natural product components in actual water samples prior to disinfection. More importantly, prechlorination of humic acid generated 3-hydroxycoumarin and monohydroxy-monomethyl-substituted coumarin with a total yield of ≤10.1%, which suggested the humic substance in raw water is an important source of coumarins. 7-Hydroxycoumarin, 6-hydroxy-4-methylcoumarin, 6,7-dihydroxycoumarin, and 7-methoxy-4-methylcoumarin were identified in raw water by high-performance liquid chromatography-tandem high-resolution mass spectrometry because only some coumarin standards were commercially available. Their chlorination generated monochlorinated and polychlorinated coumarins, and their structures were confirmed by the synthesized standards. These products could form at various dosages of chlorine and pH levels, and some with a concentration of 600 ng/L can be stable in tap water for days. 3,6,8-Trichloro-7-hydroxycoumarin, 3-chloro-7-methoxy-4-methylcoumarin, and 3,6-dichloro-7-methoxy-4-methylcoumarin were first identified in finished water with concentrations of 0.0670, 78.1, and 14.7 ng/L, respectively, but not in source water, suggesting that they are new DBPs formed during disinfection. The cytotoxicity of 3-chloro-7-methoxy-4-methylcoumarin in CHO-K1 cells was comparable to those of 2,6-dibromo-1,4-benzoquinone and 2,6-dichloro-1,4-benzoquinone in TIC-Tox analyses, suggesting that further investigation of their occurrence and control in drinking water systems is warranted.


Subject(s)
Coumarins , Cricetulus , Drinking Water , Halogenation , Water Pollutants, Chemical , Coumarins/chemistry , Drinking Water/chemistry , Animals , CHO Cells , Cricetinae , Chromatography, High Pressure Liquid , Water Purification
18.
Environ Sci Technol ; 58(17): 7672-7682, 2024 Apr 30.
Article in English | MEDLINE | ID: mdl-38639327

ABSTRACT

The development of efficient technologies for the synergistic catalytic elimination of NOx and chlorinated volatile organic compounds (CVOCs) remains challenging. Chlorine species from CVOCs are prone to catalyst poisoning, which increases the degradation temperature of CVOCs and fails to balance the selective catalytic reduction of NOx with the NH3 (NH3-SCR) performance. Herein, synergistic catalytic elimination of NOx and chlorobenzene has been originally demonstrated by using phosphotungstic acid (HPW) as a dechlorination agent to collaborate with CeO2. The conversion of chlorobenzene was over 80% at 270 °C, and the NOx conversion and N2 selectivity reached over 95% at 270-420 °C. HPW not only allowed chlorine species to leave as inorganic chlorine but also enhanced the BroÌ·nsted acidity of CeO2. The NH4+ produced in the NH3-SCR process can effectively promote the dechlorination of chlorobenzene at low temperatures. HPW remained structurally stable in the synergistic reaction, resulting in good water resistance and long-term stability. This work provides a cheaper and more environmentally friendly strategy to address chlorine poisoning in the synergistic reaction and offers new guidance for multipollutant control.


Subject(s)
Chlorobenzenes , Catalysis , Chlorobenzenes/chemistry , Volatile Organic Compounds/chemistry , Chlorine/chemistry , Cerium/chemistry , Halogenation
19.
Langmuir ; 40(17): 9197-9204, 2024 Apr 30.
Article in English | MEDLINE | ID: mdl-38639710

ABSTRACT

Waterborne coatings with intrinsic antibacterial attributes have attracted significant attention due to their potential in mitigating microbial contamination while simultaneously addressing the environmental drawbacks of their solvent-based counterparts. Typically, antimicrobial coatings are designed to resist and eliminate microbial threats, encompassing challenges such as biofilm formation, fungal contamination, and proliferation of black mold. Iodine, when solubilized using ethylene glycol and incorporated as a complex into waterborne latex dispersions, has shown remarkable antimicrobial activity. Here, we demonstrate the effect of the film formation process of these iodinated latex dispersions on their antimicrobial properties. The effect of iodine on the surface morphology and mechanical, adhesion, and antimicrobial properties of the generated films was investigated. Complete integration and uniform distribution of iodine in the films were confirmed through UV-vis spectrophotometry and a laser Raman imaging system (LRIS). In terms of properties, iodinated films showed improved mechanical strength and adhesion compared with blank films. Further, the presence of iodine rendered the films rougher, making them susceptible to bacterial adhesion, but interestingly provided enhanced antibiofilm activity. Moreover, thicker films had a lower surface roughness and reduced biofilm growth. These observations are elucidated through the complex interplay among film thickness, surface morphology, and iodine properties. The insights into the interlink between the film formation process and antimicrobial properties of iodinated latex dispersions will facilitate their enhanced application as sustainable alternatives to solvent-based coatings.


Subject(s)
Biofilms , Iodine , Latex , Latex/chemistry , Latex/pharmacology , Iodine/chemistry , Iodine/pharmacology , Biofilms/drug effects , Surface Properties , Anti-Infective Agents/chemistry , Anti-Infective Agents/pharmacology , Anti-Bacterial Agents/pharmacology , Anti-Bacterial Agents/chemistry , Bacterial Adhesion/drug effects , Microbial Sensitivity Tests , Halogenation
20.
Sci Rep ; 14(1): 9168, 2024 04 22.
Article in English | MEDLINE | ID: mdl-38649777

ABSTRACT

Fluorinated graphene, a two-dimensional nanomaterial composed of three atomic layers, a central carbon layer sandwiched between two layers of fluorine atoms, has attracted considerable attention across various fields, particularly for its potential use in biomedical applications. Nonetheless, scant effort has been devoted to assessing the potential toxicological implications of this nanomaterial. In this study, we scrutinize the potential impact of fluorinated graphene on a protein model, HP35 by utilizing extensive molecular dynamics (MD) simulation methods. Our MD results elucidate that upon adsorption to the nanomaterial, HP35 undergoes a denaturation process initiated by the unraveling of the second helix of the protein and the loss of the proteins hydrophobic core. In detail, substantial alterations in various structural features of HP35 ensue, including alterations in hydrogen bonding, Q value, and RMSD. Subsequent analyses underscore that hydrophobic and van der Waals interactions (predominant), alongside electrostatic energy (subordinate), exert influence over the adsorption of HP35 on the fluorinated graphene surface. Mechanistic scrutiny attests that the unrestrained lateral mobility of HP35 on the fluorinated graphene nanomaterial primarily causes the exposure of HP35's hydrophobic core, resulting in the eventual structural denaturation of HP35. A trend in the features of 2D nanostructures is proposed that may facilitate the denaturation process. Our findings not only substantiate the potential toxicity of fluorinated graphene but also unveil the underlying molecular mechanism, which thereby holds significance for the prospective utilization of such nanomaterials in the field of biomedicine.


Subject(s)
Graphite , Hydrogen Bonding , Molecular Dynamics Simulation , Neurofilament Proteins , Peptide Fragments , Protein Conformation, alpha-Helical , Graphite/chemistry , Graphite/toxicity , Hydrophobic and Hydrophilic Interactions , Protein Unfolding/drug effects , Halogenation , Adsorption , Nanostructures/chemistry , Nanostructures/toxicity
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