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Journal of Bacteriology Nov 2020Here, we investigate the mycobacterial response to the combined stress of an organic oxidant (cumene hydroperoxide [CHP]) and a solvent (ethanol). To understand the...
Here, we investigate the mycobacterial response to the combined stress of an organic oxidant (cumene hydroperoxide [CHP]) and a solvent (ethanol). To understand the interaction between the two stressors, we treated cells to a range of ethanol concentrations (2.5% to 10% [vol/vol]) in combination with a subinhibitory concentration of 1 mM CHP. It was observed that the presence of CHP increases the efficacy of ethanol in inducing rapid cell death. The data further suggest that ethanol reacts with the alkoxy radicals to produce ethanol-derived peroxides. These radicals induce significant membrane damage and lead to cell lysis. The ethanol-derived radicals were primarily recognized by the cells as organic radicals, as was evident by the differential upregulation of the genes that function in cells treated with the combination of ethanol and CHP. The role of organic peroxide reductase, Ohr, was further confirmed by the significantly higher sensitivity of the deletion mutant to CHP and the combined stress treatment of CHP and ethanol. Moreover, we also observed the sigma factor σ to be important for the cells treated with ethanol alone as well as the aforementioned combination. A Δ mutant strain had significantly higher susceptibility to the stress conditions. This finding was correlated with the σ-dependent transcriptional regulation of and In summary, our data indicate that the combination of low levels of ethanol and organic peroxides induce ethanol-derived organic radicals that lead to significant oxidative stress on the cells in a concentration-dependent manner. Bacterial response to a combination of stresses can be unexpected and very different compared with that of an individual stress treatment. This study explores the physiological and transcriptional response of mycobacteria in response to the combinatorial treatment of an oxidant with the commonly used solvent ethanol. The presence of a subinhibitory concentration of organic peroxide increases the effectiveness of ethanol by inducing reactive peroxides that destroy the membrane integrity of cells in a significantly short time span. Our work elucidates a mechanism of targeting the complex mycobacterial membrane, which is its primary source of intrinsic resistance. Furthermore, it also demonstrates the importance of exploring the effect of various stress conditions on inducing bacterial clearance.
Topics: Bacterial Proteins; Benzene Derivatives; Ethanol; Gene Expression Regulation, Bacterial; Mycobacterium smegmatis; Oxidants; Oxidative Stress
PubMed: 32928928
DOI: 10.1128/JB.00222-20 -
Targeting glutathione S-transferase P and its interactome with selenium compounds in cancer therapy.Biochimica Et Biophysica Acta. General... Jan 2019The glutathione (GSH) S-transferase family of detoxification and signalling proteins represents a major hub for the metabolism of Selenium-derived compounds. At the same... (Review)
Review
The glutathione (GSH) S-transferase family of detoxification and signalling proteins represents a major hub for the metabolism of Selenium-derived compounds. At the same time, these compounds can be used to modulate the expression and multiple activities of GSTs and other glutathione-dependent genes, that are important aspects in both the chemoprevention and therapy of drug-resistant cancers. In this context, the isoform GSTP-1 (GSTP) appears to play a fundamental role. Besides promoting GSH-dependent detoxification of cellular electrophiles, GSTP physically interacts with a number of small molecules and cellular proteins producing regulatory effects across the main signal transduction and transcription pathways (identified as the "regulatory interactome of GSTP"). An emerging molecular mechanism behind such regulatory function is the activity of GSTP as a redox chaperonine responsible for the selective glutathionylation of protein Cys residues in the different subcellular compartments. The redox-sensitive transcription factor Nrf2 was recently identified as one of the regulatory nodes of this interactome at the interface between inflammation, adaptive stress response, and cell death pathways. The influence of Nrf2 in the stress response to cellular electrophiles and its regulatory interaction with GSTP are discussed in this review suggesting the hypothesis that this interaction may represent the actual pharmacological target of Se compounds with thiol peroxidase activity. These points are critically evaluated with a view to further development of these compounds in cancer prevention and the chemotherapy of drug-resistant tumours.
Topics: Animals; Drug Resistance, Neoplasm; Fibroblasts; Glutathione; Glutathione S-Transferase pi; Humans; Hydrogen Peroxide; Inflammation; Lipids; Mice; Mitochondria; Neoplasms; Oxidants; Oxidation-Reduction; Oxidative Stress; Oxygen; Protein Binding; Selenium; Selenium Compounds; Signal Transduction; Sulfhydryl Compounds
PubMed: 30290218
DOI: 10.1016/j.bbagen.2018.09.023 -
Water Research Feb 2021Synthetic or natural mediators (Med) can enhance the transformation of different types of organic pollutants by mild oxidants, which has been extensively studied in... (Review)
Review
Synthetic or natural mediators (Med) can enhance the transformation of different types of organic pollutants by mild oxidants, which has been extensively studied in literature. This enhancing effect is attributed to the following two steps: (i) mild oxidants react with Med forming Med with higher reactivity, and then (ii) these organic pollutants are more readily transformed by Med. The present work reviews the latest findings on the formation of Med from the reactions of synthetic (i.e., 2,2'-azino-bis(3-ethylbenzothiazoline)-6-sulfonate (ABTS) and 1-hydroxybenzotriazole (HBT)) or natural mediators (i.e., syringaldehyde (SA), acetosyringone (AS), p-coumaric acid, and catechol) with mild oxidants such as laccase, manganese oxidants including permanganate (Mn(VII)) and MnO, and ferrate (Fe(VI)), as well as the transformation of organic pollutants including phenols, amines, polycyclic aromatic hydrocarbons (PAHs), organic dyes, pulp, and perfluoroalkyl acids (PFAAs) by Med. First, reaction kinetics and mechanisms of the oxidation of synthetic or natural mediators by these mild oxidants were summarized. Reactivity and pathways of synthetic Med including ABTS, ABTS, HBT or natural Med including phenoxy radicals and quinone-type compounds reacting with different organic pollutants were then discussed. Finally, the possibilities of engineering applications and new perspectives were assessed on the combinations of different types of mild oxidants with synthetic or natural mediators for the treatment of various organic pollutants.
Topics: Environmental Pollutants; Laccase; Manganese Compounds; Oxidants; Oxidation-Reduction; Oxides
PubMed: 33271411
DOI: 10.1016/j.watres.2020.116667 -
Astrobiology Dec 2016In 1976, the Viking landers carried out the most comprehensive search for organics and microbial life in the martian regolith. Their results indicate that Mars' surface... (Review)
Review
In 1976, the Viking landers carried out the most comprehensive search for organics and microbial life in the martian regolith. Their results indicate that Mars' surface is lifeless and, surprisingly, depleted in organics at part-per-billion levels. Several biology experiments on the Viking landers gave controversial results that have since been explained by the presence of oxidizing agents on the surface of Mars. These oxidants may degrade abiotic or biological organics, resulting in their nondetection in the regolith. As several exploration missions currently focus on the detection of organics on Mars (or will do so in the near future), knowledge of the oxidative state of the surface is fundamental. It will allow for determination of the capability of organics to survive on a geological timescale, the most favorable places to seek them, and the best methods to process the samples collected at the surface. With this aim, we review the main oxidants assumed to be present on Mars, their possible formation pathways, and those laboratory studies in which their reactivity with organics under Mars-like conditions has been evaluated. Among the oxidants assumed to be present on Mars, only four have been detected so far: perchlorate ions (ClO) in salts, hydrogen peroxide (HO) in the atmosphere, and clays and metal oxides composing surface minerals. Clays have been suggested as catalysts for the oxidation of organics but are treated as oxidants in the following to keep the structure of this article straightforward. This work provides an insight into the oxidizing potential of the surface of Mars and an estimate of the stability of organic matter in an oxidizing environment. Key Words: Mars surface-Astrobiology-Oxidant-Chemical reactions. Astrobiology 16, 977-996.
Topics: Extraterrestrial Environment; Mars; Oxidants; Oxidation-Reduction; Soil; Space Flight
PubMed: 27925795
DOI: 10.1089/ast.2016.1502 -
Molecules (Basel, Switzerland) Jun 2015A variety of selenium compounds were proven to be useful reagents and catalysts for organic synthesis over the past several decades. The most interesting aspect, which... (Review)
Review
A variety of selenium compounds were proven to be useful reagents and catalysts for organic synthesis over the past several decades. The most interesting aspect, which emerged in recent years, concerns application of hydroperoxide/selenium(IV) oxide and hydroperoxide/organoselenium catalyst systems, as "green reagents" for the oxidation of different organic functional groups. The topic of oxidations catalyzed by organoselenium derivatives has rapidly expanded in the last fifteen years This paper is devoted to the synthetic applications of the oxidation reactions mediated by selenium compounds such as selenium(IV) oxide, areneseleninic acids, their anhydrides, selenides, diselenides, benzisoselenazol-3(2H)-ones and other less often used other organoselenium compounds. All these compounds have been successfully applied for various oxidations useful in practical organic syntheses such as epoxidation, 1,2-dihydroxylation, and α-oxyfunctionalization of alkenes, as well as for ring contraction of cycloalkanones, conversion of halomethyl, hydroxymethyl or active methylene groups into formyl groups, oxidation of carbonyl compounds into carboxylic acids and/or lactones, sulfides into sulfoxides, and secondary amines into nitrones and regeneration of parent carbonyl compounds from their azomethine derivatives. Other reactions such as dehydrogenation and aromatization, active carbon-carbon bond cleavage, oxidative amidation, bromolactonization and oxidation of bromide for subsequent reactions with alkenes are also successfully mediated by selenium (IV) oxide or organoselenium compounds. The oxidation mechanisms of ionic or free radical character depending on the substrate and oxidant are discussed. Coverage of the literature up to early 2015 is provided. Links have been made to reviews that summarize earlier literature and to the methods of preparation of organoselenium reagents and catalysts.
Topics: Anhydrides; Carboxylic Acids; Catalysis; Epoxy Compounds; Green Chemistry Technology; Hydrogen Peroxide; Lactones; Nitrogen Oxides; Organoselenium Compounds; Oxidation-Reduction; Oxygen; Selenium Oxides; Sulfides; Sulfoxides
PubMed: 26046320
DOI: 10.3390/molecules200610205 -
Journal of Environmental Management Nov 2023Landfill leachate is a discrete volumetric component of municipal solid waste; hence, researchers and professionals are more concerned about it because of its obscurity.... (Review)
Review
Landfill leachate is a discrete volumetric component of municipal solid waste; hence, researchers and professionals are more concerned about it because of its obscurity. Innovative treatment and emerging technologies are being scrutinized to address the treatment of landfill leachate challenges. The leading target of this review was to examine the possibility of removing recalcitrant organic pollutants from landfill leachate by photocatalytic-based advanced oxidation processes. A summary of the systematic applicability of conventional treatment for landfill leachate is provided, with a focus on physico-chemical and biological processes. The biological treatment, such as aerobic and anaerobic digestion, is an excellent technique for treating highly concentrated organic pollutants in the wastewater. However, Leachate can scarcely be treated using conventional techniques since it is enriched with refractory organics and inorganic ions. It is clear from the literature review that none of the available combinations of physico-chemical and biological treatments are entirely relevant for the removal of recalcitrant organic pollutants from leachate. Recently, the photo-assisted TiO/ZnO oxidation has shown an excessively potential and feasible way to treat landfill leachate. TiO/ZnO photocatalysis is currently developing to treat recalcitrant organic pollutants from landfill leachate. The effect of operating parameters reveals that pH and temperature affect the reaction rate. The addition of oxidant HO to the TiO/ZnO suspension suggests that TiO leads to an increase in the rate of reaction when compared to ZnO. Photocatalytic remediation technique of landfill leachate would support the goal of environmental sustainability by greatly enhancing the effectiveness of treated leachate reutilization. In this review, the selection of the best photocatalytic treatment for leachate based on its systematic relevance and potential conditions, characteristics, cost-effectiveness, essential controlling, discharge limit, long-term environmental effects, and its future study perspectives are emphasized and discussed.
Topics: Waste Disposal, Fluid; Water Pollutants, Chemical; Hydrogen Peroxide; Zinc Oxide; Oxidation-Reduction
PubMed: 37619385
DOI: 10.1016/j.jenvman.2023.118794 -
Oxidative pretreatment of lignocellulosic biomass for enzymatic hydrolysis: Progress and challenges.Bioresource Technology Jan 2023Deconstruction of cell wall structure is important for biorefining of lignocellulose to produce various biofuels and chemicals. Oxidative delignification is an effective... (Review)
Review
Deconstruction of cell wall structure is important for biorefining of lignocellulose to produce various biofuels and chemicals. Oxidative delignification is an effective way to increase the enzymatic digestibility of cellulose. In this work, the current research progress on conventional oxidative pretreatment including wet oxidation, alkaline hydrogen peroxide, organic peracids, Fenton oxidation, and ozone oxidation were reviewed. Some recently developed novel technologies for coupling pretreatment and direct biomass-to-electricity conversion with recyclable oxidants were also introduced. The primary mechanism of oxidative pretreatment to enhance cellulose digestibility is delignification, especially in alkaline medium, thus eliminating the physical blocking and non-productive adsorption of enzymes by lignin. However, the cost of oxidative delignification as a pretreatment is still too expensive to be applied at large scale at present. Efforts should be made particularly to reduce the cost of oxidants, or explore valuable products to obtain more revenue.
Topics: Biomass; Hydrolysis; Lignin; Biofuels; Cellulose; Oxidative Stress; Oxidants
PubMed: 36323374
DOI: 10.1016/j.biortech.2022.128208 -
Environmental Science and Pollution... Nov 2022The sol-gel route was used to synthesize a biophenolic resin from a blend of Kraft black liquor and condensed tannin. The biobased resin has an amorphous structure and...
The sol-gel route was used to synthesize a biophenolic resin from a blend of Kraft black liquor and condensed tannin. The biobased resin has an amorphous structure and diversified surface functional groups. The biomaterial thermal stability was improved by Kraft black liquor, which increased the fixed carbon yield by 19.78% in an oxidant medium and 9.07% in an inert medium. Moreover, the presence of fixed carbon and char is positively related to the material flame retardant property. Additionally, impedance measurements were used to understand the physical phenomena occurring at the polymeric matrix's interface and the material's final properties. The biobased resin characterization and the considerable increase in the presence of micropollutants in surface and water bodies suggest the new biomaterial application in the adsorption process. Thus, its adsorption capacity toward several organic and inorganic micropollutants and its effectiveness in complex water matrices were evaluated. Methylene blue was used as a model compound to assess the influence of the resin composition on the adsorption capacity, and the type H isotherm indicates the high affinity of the biobased resin toward the micropollutant. The adsorption occurs in multilayer by intermolecular interaction and electrostatic forces. The amount of Kraft black liquor favored the adsorption, and the adsorption capacity was greater than 1250 mg g. When inorganic compounds were evaluated, the carboxyl and phenol groups favor the biomaterial affinity toward metal ions. Cu and Ni were completely removed from the contaminated water, and the adsorption capacity of the other inorganic compounds was: Pb (36.97 mg g), Al (22.17 mg g), Ba (12.76 mg g), Ag (33.85 mg g), and Fe (19.44 mg g). In contrast, the adsorption capacity of the organic micropollutants was: 2,4-D (3.09 mg g), diuron (5.89 mg g), atrazine (2.71 mg g), diclofenac (2.04 mg g), caffeine (5.79 mg g), acetaminophen (4.80 mg g), methylene Blue (106.66 mg g), and methyl orange (30.48 mg g). The results pointed that the adsorption efficiency of organic micropollutants increases with the distribution coefficient (logD), indicating the biobased resin affinity toward more lipophilic compounds and ionized species.
Topics: Water Purification; Water Pollutants, Chemical; Proanthocyanidins; Atrazine; Methylene Blue; Diclofenac; Acetaminophen; Caffeine; Diuron; Flame Retardants; Lead; Adsorption; Carbon; 2,4-Dichlorophenoxyacetic Acid; Water; Phenols; Oxidants; Biocompatible Materials; Kinetics
PubMed: 35091942
DOI: 10.1007/s11356-021-18250-3 -
Journal of Environmental Sciences... Jun 2023Many studies have successfully built iron-mediated materials to activate or catalyze Fenton-like reactions, with applications in water and wastewater treatment being... (Review)
Review
Many studies have successfully built iron-mediated materials to activate or catalyze Fenton-like reactions, with applications in water and wastewater treatment being investigated. However, the developed materials are rarely compared with each other regarding their performance of organic contaminant removal. In this review, the recent advances of Fenton-like processes in homogeneous and heterogeneous ways are summarized, especially the performance and mechanism of activators including ferrous iron, zero valent iron, iron oxides, iron-loaded carbon, zeolite, and metal organic framework materials. Also, this work mainly compares three O-O bond containing oxidants including hydrogen dioxide, persulfate, and percarbonate, which are environmental-friendly oxidants and feasible for in-situ chemical oxidation. The influence of reaction conditions, catalyst properties and benefits are analyzed and compared. In addition, the challenges and strategies of these oxidants in applications and the major mechanisms of the oxidation process have been discussed. This work can help understand the mechanistic insights of variable Fenton-like reactions, the role of emerging iron-based materials, and provide guidance for choosing appropriate technologies when facing real-world water and wastewater applications.
Topics: Iron; Hydrogen Peroxide; Oxidation-Reduction; Oxidants; Water; Water Pollutants, Chemical
PubMed: 36801034
DOI: 10.1016/j.jes.2022.07.037 -
Water Research Aug 2023Concerns over human health risks associated with chemical contaminants (micropollutants) in drinking waters are rising due to the increased use of reclaimed water or... (Review)
Review
Concerns over human health risks associated with chemical contaminants (micropollutants) in drinking waters are rising due to the increased use of reclaimed water or water supplies impacted by upstream wastewater discharges. Ultraviolet (UV)-driven advanced oxidation processes (UV-AOPs) using radiation sources that emit at 254 nm have been developed as advanced treatments to degrade contaminants, while those UV-AOPs can be improved towards higher radical yields and lower byproduct formation. Several previous studies have suggested that Far-UVC radiation (200-230 nm) is a promising radiance source to drive UV-AOPs because the direct photolysis of micropollutants and production of reactive species from oxidant precursors can both be improved. In this study, we summarize from the literature the photodecay rate constants of five micropollutants by direct UV photolysis, which are higher at 222 than 254 nm. We experimentally determine the molar absorption coefficients at 222 and 254 nm of eight oxidants commonly used in water treatment and present the quantum yields of the oxidant photodecay. Our experimental results also show that the concentrations of HO, Cl, and ClO generated in the UV/chlorine AOP can be increased by 5.15-, 15.76-, and 2.86-fold, respectively, by switching the UV wavelength from 254 to 222 nm. We also point out the challenges of applying Far-UVC for micropollutant abatement in water treatment, including the strong light screening effect of matrix components (e.g., carbonate, nitrate, bromide, and dissolved organic matter), the formation of byproducts via new reaction pathways, and the needs to improve the energy efficiency of the Far-UVC radiation sources.
Topics: Humans; Water Pollutants, Chemical; Wastewater; Oxidation-Reduction; Chlorine; Oxidants; Water Purification; Ultraviolet Rays; Hydrogen Peroxide
PubMed: 37290191
DOI: 10.1016/j.watres.2023.120169