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Plants produce reactive oxygen species (ROS) upon infection, which typically trigger defence mechanisms and impede pathogen proliferation. Root-knot nematodes (RKNs, Meloidogyne spp.) represent highly detrimental pathogens capable of parasitizing a broad spectrum of crops, resulting in substantial annual agricultural losses. The involvement of ROS in RKN parasitism is well acknowledged. In this study, we identified a novel effector from Meloidogyne incognita, named CATLe, that contains a conserved catalase domain, exhibiting potential functions in regulating host ROS levels. Phylogenetic analysis revealed that CATLe is conserved across RKNs. Temporal and spatial expression assays showed that the CATLe gene was specifically up-regulated at the early infection stages and accumulated in the subventral oesophageal gland cells of M. incognita. Immunolocalization demonstrated that CATLe was secreted into the giant cells of the host plant during M. incognita parasitism. Transient expression of CATLe significantly dampened the flg22-induced ROS production in Nicotiana benthamiana. In planta assays confirmed that M. incognita can exploit CATLe to manipulate host ROS levels by directly degrading H2O2. Additionally, interfering with expression of the CATLe gene through double-stranded RNA soaking and host-induced gene silencing significantly attenuated M. incognita parasitism, highlighting the important role of CATLe. Taken together, our results suggest that RKNs can directly degrade ROS products using a functional catalase, thereby manipulating host ROS levels and facilitating parasitism.

To facilitate our understanding of proteome dynamics during signaling events, robust workflows affording fast time resolution without confounding factors are essential. We present Surface-exposed protein Labeling using PeroxidaSe, H2O2, and Tyramide-derivative (SLAPSHOT) to label extracellularly exposed proteins in a rapid, specific, and sensitive manner. Simple and flexible SLAPSHOT utilizes recombinant soluble APEX2 protein applied to cells, thus circumventing the engineering of tools and cells, biological perturbations, and labeling biases. We applied SLAPSHOT and quantitative proteomics to examine the TMEM16F-dependent plasma membrane remodeling in WT and TMEM16F KO cells. Time-course data ranging from 1 to 30 min of calcium stimulation revealed co-regulation of known protein families, including the integrin and ICAM families, and identified proteins known to reside in intracellular organelles as occupants of the freshly deposited extracellularly exposed membrane. Our data provide the first accounts of the immediate consequences of calcium signaling on the extracellularly exposed proteome.

To oxidize trace concentrations of organic contaminants under conditions relevant to surface- and groundwater, air-diffusion cathodes were coupled to stainless-steel cathodes that convert atmospheric O2 into hydrogen peroxide (H2O2), which then was activated to produce hydroxyl radicals (·OH). By separating H2O2 generation from its activation and employing a flow-through electrode consisting of stainless-steel fibers, the two processes could be operated efficiently in a manner that overcame mass-transfer limitations for O2, H2O2, and trace organic contaminants. The flexibility resulting from separate control of the two processes made it possible to avoid both the accumulation of excess H2O2 and the energy losses that take place after H2O2 has been depleted. The decrease in treatment efficacy occurring in the presence of natural organic matter was substantially lower than that typically observed in homogeneous advanced oxidation processes. Experiments conducted with ionized and neutral compounds indicated that electrostatic repulsion prevented negatively charged ·OH scavengers from interfering with the oxidation of neutral contaminants. Energy consumption by the dual-cathode system was lower than values reported for other technologies intended for small-scale drinking water treatment systems. The coordinated operation of these two cathodes has the potential to provide a practical, inexpensive way for point-of-use drinking water treatment.

Rapid and precise detection of hydrogen peroxide (H2O2) holds great significance since it is linked to numerous physiological and inorganic catalytic processes. We herein developed a label-free and washing-free strategy to detect H2O2 by employing a hand-held personal glucose meter (PGM) as a signal readout device. By focusing on the fact that the reduced redox mediator ([Fe(CN)6]4-) itself is responsible for the final PGM signal, we developed a new PGM-based strategy to detect H2O2 by utilizing the target H2O2-mediated oxidation of [Fe(CN)6]4- to [Fe(CN)6]3- in the presence of horseradish peroxidase (HRP) and monitoring the reduced PGM signal in response to the target amount. Based on this straightforward and facile design principle, H2O2 was successfully determined down to 3.63 μM with high specificity against various non-target molecules. We further demonstrated that this strategy could be expanded to identify another model target choline by detecting H2O2 produced through its oxidation promoted by choline oxidase. Moreover, we verified its practical applicability by reliably determining extracellular H2O2 released from the breast cancer cell line, MDA-MB-231. This work could evolve into versatile PGM-based platform technology to identify various non-glucose target molecules by employing their corresponding oxidase enzymes, greatly advancing the portable biosensing technologies.

As a new type of artificial enzyme, a nanozyme is an ideal substitute for natural enzymes and has been successfully applied in many fields. However, in the application of biomolecular detection, most nanozymes have the disadvantages of long reaction times or high detection limits, prompting researchers to search for new efficient nanozymes. In this work, the enzyme-like activities of three polyoxometalate-based iron-organic complexes ([Fe(bpp)2](Mo6O19), [Fe(bpp)2]2(Mo8O26)·2CH3OH, and [Fe(bpp)2]4H[Na(Mo8O26)]3), namely, FeMo6, Fe2Mo8, and Fe4Mo8Na, were analyzed. All three polyoxometalate-based iron-organic complexes were found to be capable of catalyzing hydrogen peroxide (H2O2) to oxidize 3,3′,5,5′-tetramethylbenzidine and o-phenylenediamine, resulting in visible color changes, further exhibiting peroxidase-like activity. Results showed that Fe4Mo8Na had more active sites due to its long chain structure, endowing more prominent peroxidase-like activity compared with Fe2Mo8 and FeMo6. A colorimetric sensing platform for H2O2 and ascorbic acid detection based on Fe4Mo8Na was established. The linear response range for H2O2 detection was 0.5–100 μM, and the detection limit was 0.143 μM. The linear response for ascorbic acid detection ranges from 0 to 750 μM with a detection limit of 1.07 μM. This study provides a new perspective for developing new nanozymes and expanding the sensing and detection application of nanozymes. [ABSTRACT FROM AUTHOR]

Nanozymes are nanomaterials with mimetic enzyme properties and the related research has attracted much attention. It is of great value to develop methods to construct nanozymes and to study their application in bioanalysis. Herein, the metal–ligand cross-linking strategy was developed to fabricate superstructure nanozymes. This strategy takes advantage of being easy to operate, adjustable, cheap, and universal. The fabricated superstructure nanozymes possess efficient peroxidase-like catalytic activity. The enzyme reaction kinetic tests demonstrated that for TMB and H2O2, the Km is 0.229 and 1.308 mM, respectively. Furthermore, these superstructure nanozymes are applied to highly efficient and sensitive detection of glucose. The linear range for detecting glucose is 20–2000 μM, and the limit of detection is 17.5 μM. Furthermore, mechanistic research illustrated that this integrated system oxidizes glucose to produce hydrogen peroxide and further catalyzes the production of ·OH and O2·–, which results in a chromogenic reaction of oxidized TMB for the detection of glucose. This work could not only contribute to the development of efficient nanozymes but also inspire research in the highly sensitive detection of other biomarkers. [ABSTRACT FROM AUTHOR]

Nanozyme technology has gained significant regard and been successfully implemented in various applications including chemical sensing, bio-medicine, and environmental monitoring. Fe-CDs were synthesized and characterized well in this study. As compared to HRP (3.7 mM), the Fe-CDs exhibited a higher affinity towards H2O2 (0.2 mM) using the steady-state kinetic assay and stronger catalytic capability by changing the color of TMB to the blue color of the oxidized state, oxTMB. Additionally, an efficient peroxidase mimic, Fe-CDs/GOx, based on the hybrid cascade system to produce in situ H2O2 for the visual detection of glucose (color change: colorless to blue, and then to green), has been developed in detail, with limits of detection (LODs) for H2O2 and glucose of 0.33 μM and 1.17 μM, respectively. The changes further demonstrate a linear relationship between absorbance and H2O2 concentration, ranging from 10 to 60 μM, and for glucose (1 to 60 μM). To assess the accuracy and detection capability of the Fe-CDs/GOx system, we evaluated a real human serum sample obtained from adult males in a local hospital. In conclusion, Fe-CDs serving as a peroxidase mimic have the potential for various applications in the fields of biomedicine and nanozymes. [ABSTRACT FROM AUTHOR]

The impact of climate change on agricultural production is apparent due to declining irrigation water availability vis-à-vis rising drought stress, particularly affecting summer crops. Growing evidence suggests that zinc (Zn) supplementation may serve as a potential drought stress management strategy in agriculture. Field studies were conducted using soybean (Glycine max var. Saba) as a model crop to test whether foliar application of zinc oxide nanoparticles (ZnO-NPs) or conventional Zn fertilizer (ZnSO4) would mitigate drought-related water stress and improve soybean yield. Each fertilizer was foliar applied twice at a two-week interval during the flowering stage. Experiments were concurrently conducted under non-drought conditions (70% field capacity) for comparison. Results showed drought significantly reduced relative water content, chlorophyll-a, and chlorophyll-b in untreated control plants by 35.7%, 47.7%, and 41.4%, respectively, compared to non-drought conditions (p < 0.05). Under drought conditions, ZnO-NPs (200 mg Zn/L) led to 33.1% and 20.7% increase in chlorophyll-a and chlorophyll-b levels, respectively, compared to ZnSO4 at 400 mg Zn/L. Likewise, catalase, peroxidase and superoxide dismutase activities increased by 62.6%, 39.5% and 28.5%, respectively, with ZnO-NPs (200 mg Zn/L) under drought compared to non-drought conditions. Proline was significantly increased under drought but was remarkably suppressed (~ 54% lower) with ZnO-NPs (200 mg Zn/L) treatment. More importantly, the highest seed yield was observed with ZnO-NPs (200 mg Zn/L) treatment under drought (39% higher than untreated control) and non-drought (79.4% higher than control) conditions. Overall, the findings suggest that ZnO-NPs could promote seed yield in soybean under drought stress via increased antioxidant activities, increased relative water content, decreased stress-related proline content, and increased photosynthetic pigments. It is recommended that foliar application of 200 mg Zn/L as ZnO-NPs could serve as an effective drought stress management strategy to improve soybean yield. [ABSTRACT FROM AUTHOR]

This work combines the nanoconfined material with the air-breathing gas diffusion electrode equips a wide practical range of applications for the synthesis of high-yield H 2 O 2 and upgrading of H 2 O 2 products. [Display omitted] • Yolk-shell SnS 2 @CSs Z-scheme nanoreactor is controllably synthesized. • Hydrogen peroxide production is increased through the nano-confinement effect. • Continuous hydrophobic layers allow air to spontaneously diffuse into the AGPE. • The photoelectrode has a good reusability and stability for activation of O 2 /H 2 O. • Hydrogen peroxide is produced under neutral condition media. The diffusion and adsorption properties of the O 2 /H 2 O corpuscles at active sites play a crucial role in the fast photo-electrocatalytic reaction of hydrogen peroxide (H 2 O 2) production. Herein, SnS 2 nanosheets with abundant interfacial boundaries and large specific areas are encapsulated into hollow mesoporous carbon spheres (CSs) with flexibility, producing a yolk-shell SnS 2 @CSs Z-scheme photocatalyst. The nanoconfined microenvironment of SnS 2 @CSs could enrich O 2 /H 2 O in catalyst cavities, which allows sufficient internal O 2 transfer, improving the surface chemistry of catalytic O 2 to O 2 − conversion and increasing reaction kinetics. By shaping the mixture of SnS 2 @CSs and polytetrafluoroethylene (PTFE) on carbon felt (CF) using the vacuum filtration method, the natural air-breathing gas diffusion photoelectrode (AGPE) was prepared, and it can achieve an accumulated concentration of H 2 O 2 about 12 mM after a 10 h stability test from pure water at natural pH without using electrolyte and sacrificial agents. The H 2 O 2 product is upgraded through one downstream route of conversion of H 2 O 2 to sodium perborate. The improved H 2 O 2 production performance could be ascribed to the combination of the confinement effect of SnS 2 @CSs and the rich triple phase interfaces with the continuous hydrophobic layer and hydrophilic layer to synergistically modulate the photoelectron catalytic microenvironment, which enhanced the transfer of O 2 mass and offered a stronger affinity to oxygen bubbles. The strategy of combining the confined material with the air-breathing gas diffusion electrode equips a wide practical range of applications for the synthesis of high-yield hydrogen peroxide. [ABSTRACT FROM AUTHOR]

[Display omitted] Piezocatalysis has emerged as a sustainable alternative for hydrogen peroxide production. However, the current development of efficient piezocatalysts is predominantly focusing on those conventional piezoelectric ceramic oxides with high permittivity and limited catalytic activities. Therefore, innovative approaches to develop novel piezocatalysts in particular from these outstanding paraelectric semiconductors are highly required. In this work, by employing a feasible doping strategy, robust piezoelectric property is created on the Ba 2 Nb 2-x Fe x O 6-δ double perovskite oxides, typically characterized by a stable paraelectric cubic structure. Optimum Fe doping not only intensifies the double perovskite phase but also inspires a phase transition from a centrosymmetric cubic to a piezoelectric tetragonal phase, thereby achieving desirable piezoelectricity and enabling a series of favorable physical properties including redox activity, active sites of anion defects, reduced bandgap, and increased free charge density. All these are important factors to enhance piezocatalytic activity. As a result, Ba 2 NbFeO 6-δ achieved by the optimum Fe doping demonstrated exceptional piezocatalytic H 2 O 2 yield of 512 and 690 µmol g-1 h−1 under atmosphere and oxygen-purging conditions, respectively, without the presence of any sacrificial agents. Mechanistic investigations reveal that both water oxidation and oxygen reduction involve in the H 2 O 2 production, wherein piezopotential plays a critical role not only in facilitating the charge carrier separation and transportation but also in modulating the band structure to enhance the catalyst redox capacity. This study offers a feasible and universal strategy for the design of novel piezocatalysts, expanding the windows for catalyst selection for piezocatalysis. [ABSTRACT FROM AUTHOR]

Summary Flooding is a widespread natural disaster that causes tremendous yield losses of global food production. Rice is the only cereal capable of growing in aquatic environments. Direct seeding by which seedlings grow underwater is an important cultivation method for reducing rice production cost. Hypoxic germination tolerance and root growth in waterlogged soil are key traits for rice adaptability to flooded environments. Alternative oxidase (AOX) is a non‐ATP‐producing terminal oxidase in the plant mitochondrial electron transport chain, but its role in hypoxia tolerance had been unclear. We have discovered that AOX1a is necessary and sufficient to promote germination/coleoptile elongation and root development in rice under flooding/hypoxia. Hypoxia enhances endogenous H2O2 accumulation, and H2O2 in turn activates an ensemble of regulatory genes including AOX1a to facilitate the conversion of deleterious reactive oxygen species to H2O2 in rice under hypoxia. We show that AOX1a and H2O2 act interdependently to coordinate three key downstream events, that is, glycolysis/fermentation for minimal ATP production, root aerenchyma development and lateral root emergence under hypoxia. Moreover, we reveal that ectopic AOX1a expression promotes vigorous root and plant growth, and increases grain yield under regular irrigation conditions. Our discoveries provide new insights into a unique sensor–second messenger pair in which AOX1a acts as the sensor perceiving low oxygen tension, while H2O2 accumulation serves as the second messenger triggering downstream root development in rice against hypoxia stress. This work also reveals AOX1a genetic manipulation and H2O2 pretreatment as potential targets for improving flooding tolerance in rice and other crops. [ABSTRACT FROM AUTHOR]

This work investigated the photochemical degradation of malachite green (MG), a cationic triphenylmethane dye used as a coloring agent, fungicide, and antiseptic. UV photolysis was ineffective in the removal of MG as only 12.35% degradation of MG (10 mg/L) was achieved after 60 min of irradiation. In contrast, 100.00% degradation of MG (10 mg/L) was observed after 60 min of irradiation in the presence of 10 mM H2O2 by UV/H2O2 at pH 6.0. Similarly, complete removal (100.00%) of MG was observed at 30 min of the reaction time by UV/H2O2/Fe2+ employing [MG]0 = 10 mg/L, [H2O2]0 = 10 mM, [Fe2+]0 = 2.5 mg/L, and [pH]0 = 3.0. For the UV/H2O2 process, the degradation efficiency was higher at pH 6.0 than at pH 3.0 as the k obs values were 0.0873 and 0.0690 min−1, respectively. However, UV/H2O2/Fe2+ showed higher reactivity at pH 3.0 than at pH 6.0. Chloride and nitrate ions slightly inhibited the removal efficiency of MG by both UV/H2O2 and UV/H2O2/Fe2+ processes. Moreover, three degradation products (DPs) of MG, (i) 4-dimethylamino-benzophenone (DABP), (ii) 4-amino-benzophenone (ABP), and (iii) 4-dimethylamino-phenol (DAP), were identified by GC-MS during the UV/H2O2 treatment. These DPs were found to demonstrate higher aquatic toxicity than the parent MG, suggesting that researchers should focus on the removal of target pollutants as well as their DPs. Nevertheless, the results of this study indicate that both UV/H2O2 and UV/H2O2/Fe2+ processes could be implemented to alleviate the harmful environmental impacts of dye and textile industries. [ABSTRACT FROM AUTHOR]

Reactive oxygen species (ROS) are physiological byproducts of neuronal metabolism. However, an imbalance between ROS generation and antioxidant capacity, often driven by dysregulated pro-oxidant enzymes like nicotinamide adenine dinucleotide phosphate oxidases (NOX), can result in deleterious oxidative stress. This oxidative stress is a critical factor in the pathogenesis of neurodegenerative diseases. While interventions with broad-spectrum antioxidants have demonstrated limited efficacy, the modulation of endogenous antioxidant mechanisms presents a promising therapeutic avenue. Here, we investigated the potential of the neuroprotective hormone prolactin to mitigate oxidative stress and subsequent neuronal cell death. Prolactin protected primary mouse hippocampal neurons from hydrogen peroxide (H2O2)-induced oxidative damage. Prolactin reduced ROS levels, lipid peroxidation, and apoptosis, and its effects were occluded by a specific prolactin receptor antagonist (G129R-hPRL). Mechanistically, prolactin suppressed H2O2-induced mRNA upregulation of pro-oxidative Nox4 and pro-apoptotic Bax. Moreover, prolactin induced nuclear factor kappa B (NF-κB) nuclear translocation, and the inhibition of the NF-κB signaling pathway abolished the neuroprotective and transcriptional effects of prolactin, indicating its central role in prolactin-mediated protection. Our findings indicate that prolactin exerts potent antioxidant and neuroprotective effects by modulating the expression of Nox4 and Bax, thereby reducing ROS generation and neuronal apoptosis. This study underscores the therapeutic potential of prolactin in attenuating oxidative stress and suggests a possible role in the treatment of neurodegenerative diseases. [ABSTRACT FROM AUTHOR]

The direct utilization of solar energy for the artificial photosynthesis of hydrogen peroxide (H2O2) provides a reliable approach for producing this high-value green oxidant. Here we report on the utility of high-entropy oxide (HEO) semiconductor as an all-in-one photocatalyst for visible light-driven H2O2 production directly from H2O and atmospheric O2 without the need of any additional cocatalysts or sacrificial agents. This high-entropy photocatalyst contains eight earth-abundant metal elements (Ti/V/Cr/Nb/Mo/W/Al/Cu) homogeneously arranged within a single rutile phase, and the intrinsic chemical complexity along with the presence of a high density of oxygen vacancies endow high-entropy photocatalyst with distinct broadband light harvesting capability. An efficient H2O2 production rate with an apparent quantum yield of 38.8% at 550 nm can be achieved. The high-entropy photocatalyst can be readily assembled into floating artificial leaves for sustained on-site production of H2O2 from open water resources under natural sunlight irradiation. An "all-in-one" high-entropy semiconductor photocatalyst enables the photocatalytic production of H2O2 from H2O and O2 under visible light without any external cocatalysts or sacrificial agents [ABSTRACT FROM AUTHOR]

Formic acid is considered a promising hydrogen carrier. Biomass‐derived formic acid can be obtained by oxidative decomposition of sugars. This study explored the production of formic acid from cellobiose, a disaccharide consisting of d‐glucose linked by β‐glycosidic bonds using heterogeneous catalysts under mild reaction conditions. The use of alkaline earth metal oxide solid base catalysts like CaO and MgO in the presence of hydrogen peroxide could afford formic acid from cellobiose at 343 K. While CaO gave 14 % yield of formic acid, the oxide itself was converted to a harmful metal peroxide, CaO2 after the reaction. In contrast, MgO could produce formic acid without the formation of the metal peroxide. The difficulty in selectively synthesizing formic acid from cellobiose using these solid base catalysts was due to the poor conversion of cellobiose to glucose. Using a combination of solid acid and base catalysts, a high formic acid yield of 33 % was obtained under mild reaction conditions due to the quantitative hydrolysis of cellobiose to glucose by a solid acid followed by the selective decomposition of glucose to formic acid by a solid base. [ABSTRACT FROM AUTHOR]

Redox reactions, involving electron transfer, are critical to human physiology. However, progress in understanding redox metabolism is hindered by flawed analytical methods. This review highlights emerging techniques that promise to revolutionize redox research, enhancing our comprehension of human health and disease. Oxygen, vital for aerobic metabolism, also produces reactive oxygen species (ROS), such as superoxide and hydrogen peroxide. While historically seen as harmful, ROS at low concentrations are now recognized as key regulators of cell signaling. A balance between ROS and antioxidants, known as redox balance, is crucial, and deviations can lead to oxidative stress. Recent studies have distinguished beneficial "oxidative eustress" from harmful "oxidative distress." New techniques, such as advanced mass spectrometry and high‐throughput immunoassays, offer improved accuracy in measuring redox states and oxidative damage. These advancements are pivotal for understanding redox signaling, cysteine oxidation, and their implications for disease. Looking ahead, the development of precision redox medicine could lead to better treatments for oxidative stress‐related diseases and foster interventions promoting health. [ABSTRACT FROM AUTHOR]

In the current work, chloro(meso-tetrakis(phenyl)porphyrin) manganese(III) [Mn(TPP)Cl] was synthesized following two steps: the preparation of meso-tetraphenylporphyrin (H⁠2TPP) and the insertion of manganese into the free porphyrin H2TPP. The compounds were characterized using SEM, FT-IR, UV, TGA/DTA, and XRD analyses. Manganese(III) meso-porphyrins exhibited hyper-type electronic spectra with a half-vacant metal orbital with symmetry, such as [dπ:dxz and dyz]. The thermal behavior of [Mn(TPP)(Cl)] changed (three-step degradation process) compared to the initial H2TPP (one-step degradation process), confirming the insertion of manganese into the core of the free porphyrin H2TPP. Furthermore, [Mn(TPP)Cl] was used to degrade calmagite (an azo dye) using H2O2 as an oxidant. The effects of dye concentration, reaction time, H2O2 dose, and temperature were investigated. The azo dye solution was completely degraded in the presence of [Mn(TPP)(Cl)]/H2O2 at pH = 6, temperature = 20 °C, C0 = 30 mg/L, and H2O2 = 40 mL/L. The computed low activation energy (Ea = 10.55 Kj/mol) demonstrated the efficiency of the proposed catalytic system for the azo dye degradation. Overall, based on the synthesis process and the excellent catalytic results, the prepared [Mn(TPP)Cl] could be used as an effective catalyst for the treatment of calmagite-contaminated effluents. [ABSTRACT FROM AUTHOR]

A benzothiazole-based derivative aggregation-induced emission (AIE) fluorescent 'turn-on' probe named 2-(2-((4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzyl)oxy)phenyl)benzo[d]thiazole (probe BT-BO) was developed and synthesized successfully for detecting hydrogen peroxide (H2O2) in living cells. The synthesis method of probe BT-BO is facile. Probe BT-BO demonstrates a well-resolved emission peak at 604 nm and the ability to prevent the interference of reactive oxygen species (ROS), various metal ions and anion ions, and good sensitivity. Additionally, the probe boasts impressive pH range versatility, a fast response time to H2O2 and low cytotoxicity. Finally, probe BT-BO was applied successfully to image A549 and Hep G2 cells to monitor both exogenous and endogenous H2O2. [ABSTRACT FROM AUTHOR]

In this study, the effectiveness of the Fenton process in removing natural organic matter (NOM) from groundwater was investigated. The subject of this study is groundwater characterised by increased content of NOM and iron (II) compounds. In laboratory-scale studies, the influence of the ratio of concentrations of Fe(II) ions, which are naturally occurring in groundwater, to hydrogen peroxide (H2O2) as well as oxidation time and pH on the removal efficiency of organic matter was determined. Indicators such as total organic carbon (TOC), dissolved organic carbon (DOC), UV absorbance at 254 nm (UV254), UV absorbance at 272 nm (UV272), and specific UV absorbance (SUVA254) were used to quantitatively and qualitatively assess the organic substances present in the raw water and after oxidation with Fenton's reagent. Analysis of the results obtained showed that the highest removal efficiency of organic substances in the deep oxidation process using the Fenton reaction was obtained for a concentration ratio of Fe(II) to H2O2 = 1:5. Acidification of the water samples to a pH of about 4 and extending the oxidation time to 30 min significantly increased the removal efficiency of organic substances including mainly dissolved organic substances containing aromatic rings. The organic substances containing aromatic rings, determined at a wavelength of 254 nm, were degraded to other organic intermediates. [ABSTRACT FROM AUTHOR]

Ascorbic acid (AA) plays an important role in many physiological and biochemical processes. Adequate quantification of AA is required for controlling the intake of AA for health management. In this study, a portable probe was fabricated based on the assembled FePO4@GO nanozyme by homogeneous precipitation. FePO4@GO exhibits excellent peroxidase (POD) activity. As an efficient free radical scavenger, ascorbic acid scavenges 1O2 free radicals produced by hydrogen peroxide catalyzed by peroxidase enzymes and then inhibits the color reaction of 3,3′,5,5′-tetramethylbenzidine (TMB). A good linear relationship between the color of the reaction system and the concentration of AA in the range of 2.5–75 μM was presented, and the detection limit is 1.25 μM. Furthermore, a visual colorimetric detection platform was constructed using a smartphone. The AA content is accurately reflected by intelligent recognition of color changes in the reaction system. It provides an alternative approach for portable and visual rapid detection of Vitamin C (VC) in medicine. Meanwhile, it also provides a reference for the assembly of an intelligent detection platform based on nanozymes. [ABSTRACT FROM AUTHOR]

Pulmonary artery endothelial cells (PAECs) are a major contributor to hypoxic pulmonary hypertension (PH) due to the possible roles of reactive oxygen species (ROS). However, the molecular mechanisms and functional roles of ROS in PAECs are not well established. In this study, we first used Amplex UltraRed reagent to assess hydrogen peroxide (H2O2) generation. The result indicated that hypoxic exposure resulted in a significant increase in Amplex UltraRed-derived fluorescence (i.e., H2O2 production) in human PAECs. To complement this result, we employed lucigenin as a probe to detect superoxide (O2−) production. Our assays showed that hypoxia largely increased O2− production. Hypoxia also enhanced H2O2 production in the mitochondria from PAECs. Using the genetically encoded H2O2 sensor HyPer, we further revealed the hypoxic ROS production in PAECs, which was fully blocked by the mitochondrial inhibitor rotenone or myxothiazol. Interestingly, hypoxia caused an increase in the migration of PAECs, determined by scratch wound assay. In contrast, nicotine, a major cigarette or e-cigarette component, had no effect. Moreover, hypoxia and nicotine co-exposure further increased migration. Transfection of lentiviral shRNAs specific for the mitochondrial Rieske iron–sulfur protein (RISP), which knocked down its expression and associated ROS generation, inhibited the hypoxic migration of PAECs. Hypoxia largely increased the proliferation of PAECs, determined using Ki67 staining and direct cell number accounting. Similarly, nicotine caused a large increase in proliferation. Moreover, hypoxia/nicotine co-exposure elicited a further increase in cell proliferation. RISP knockdown inhibited the proliferation of PAECs following hypoxia, nicotine exposure, and hypoxia/nicotine co-exposure. Taken together, our data demonstrate that hypoxia increases RISP-mediated mitochondrial ROS production, migration, and proliferation in human PAECs; nicotine has no effect on migration, increases proliferation, and promotes hypoxic proliferation; the effects of nicotine are largely mediated by RISP-dependent mitochondrial ROS signaling. Conceivably, PAECs may contribute to PH via the RISP-mediated mitochondrial ROS. [ABSTRACT FROM AUTHOR]

Deep eutectic solvent (DES) has been considered as a useful catalyst and reaction medium for various organic transformations. Herein, we report the catalytic application of novel deep eutectic solvent- based surfactant (DES surfactant) for the selective and fast oxidation of alcohols to aldehydes. The readily accessible DES surfactants (FeCl3/BHDC) was prepared using inexpensive ferric chloride (FeCl3) and benzyl hexadecyl dimethyl ammonium chloride in a simple manner. The synthesized FeCl3/BHDC was characterized using various techniques, including, FTIR spectroscopy, thermal gravimetric analysis (TGA), scanning electron microscopy (SEM), and energy- dispersive X-ray spectroscopy (EDS) to determine its structure. The catalytic activity of FeCl3/BHDC in the selective oxidation of various alcohols to corresponding aldehyde derivative was investigated. The results showed the reaction could be completed within very short reaction times ranging from 2 to 15 min, while achieving good to excellent yields. This protocol offers a facile strategy and excellent efficiency in selectively oxidizing various alcohol derivatives to their respective aldehydes and ketones, utilizing hydrogen peroxide in the presence of catalytic DES surfactant. [ABSTRACT FROM AUTHOR]

Fumarylacetoacetate hydrolase (FAH) catalyzes the final step of the tyrosine degradation pathway. In this study, we isolated and characterized two homologous BnaFAH genes in Brassica napus L. variant Westar, and then used CRISPR/Cas9-mediated targeted mutagenesis to generate a series of transgene-free mutant lines either with single or double-null bnafah alleles. Among these mutant lines, the aacc (bnafah) double-null mutant line, rather than the aaCC (bnaa06fah) mutant line, exhibited programmed cell death (PCD) under short days (SD). Histochemical staining and content measurement confirmed that the accumulation of reactive oxygen species (ROS) in bnafah was significantly higher than that in bnaa06fah. To further elucidate the mechanism of PCD, we performed transcriptomic analyses of bnaa06fah and bnafah at different SD stages. A heatmap cluster of differentially expressed genes (DEGs) revealed that PCD may be related to various redox regulatory genes involved in antioxidant activity, ROS-responsive regulation and calcium signaling. Combined with the results of previous studies, our work revealed that the expression levels of BnaC04CAT2, BnaA09/C09SAL1, BnaA08/C08ACO2, BnaA07/C06ERO1, BnaA08ACA1, BnaC04BIK1, BnaA09CRK36 and BnaA03CPK4 were significantly different and that these genes might be candidate hub genes for PCD. Together, our results underscore the ability of different PCD phenotypes to alter BnaFAH orthologs through gene editing and further elucidated the molecular mechanisms of oxidative stress-induced PCD in plants. [ABSTRACT FROM AUTHOR]

S-nitrosoglutathione reductase (GSNOR) is involved in the response to cadmium (Cd) exposure. In this study, the plants of mutant (gsnor1-3) with lossing-function of- and over-expression (GSNOROE5) of GSNOR were used to clear the role of GSNOR in Cd tolerance. GSNOR activity increased through upregulating the expression of the AtGSNOR gene and protein in Arabidopsis thaliana under Cd stress, which attenuated Cd tolerance. Oxidative damage was more serious in GSNOROE5 and was alleviated in gsnor1-3 under Cd stress, compared with Col-0. Induction of GSNOR facilitated H2O2 accumulation but inhibited catalase (CAT) activity in shoots under Cd stress. This phenotype was eliminated by 3-amino-1,2,4-triazole (3-AT), a CAT inhibitor. In addition, the expressions of AtCAT1 and AtCAT2 were down-regulated with increasing GSNOR activity under Cd stress. This suggested that GSNOR was involved in the accumulation of hydrogen peroxide (H2O2) through regulating CAT expression and activity under Cd exposure. Furthermore, Cd tolerance and CAT activity were improved by spraying S-nitrosoglutathione (GSNO) onto the surface of the leaves. The in vitro activity of CAT increased with GSNO concentration until a GSNO/CAT ratio of 2 was reached. Thus, CAT activity was relative to GSNOR through regulating the expression and S-nitrosylation level of proteins. In summary, the Cd-induced promotion of GSNOR activity aggravated Cd toxicity in plants by mediating H2O2 accumulation controlled by CAT. [ABSTRACT FROM AUTHOR]

This study presents a new dual-mode propulsion system that utilizes an electrically pumped hydrogen peroxide and kerosene supply system, specifically designed for advanced spacecraft orbit and attitude control. The system incorporates two distinct electric pumps, one for hydrogen peroxide and another for kerosene, each engineered to optimize the propellant feed for the orbit control and attitude control engines. This configuration enables precise propellant management and thrust control, which are critical for the stringent demands of modern space missions. The dual-mode capability of the propulsion system allows for the use of hydrogen peroxide both as a monopropellant in the attitude control engine and as an oxidizer in combination with kerosene in the orbit control engine. This approach simplifies the propulsion architecture while maximizing the efficiency and utility of hydrogen peroxide as a propellant. The electric pumps are essential in providing high-pressure propellant delivery, which is necessary to achieve the desired combustion characteristics and thrust parameters. Performance evaluations of the propulsion system demonstrated significant results. The orbit control engine achieved a combustion chamber pressure of 5.9 MPa and a combustion efficiency of 98.42 %. The attitude control engine, operating at a peak pressure of 4.9 MPa, exhibited a stable pulsative mode, maintaining consistent pressure levels throughout its operational cycle. These performance metrics highlight the effectiveness of the electric pump technology in enhancing propulsion system responsiveness and efficiency. This propulsion system is expected to improve spacecraft maneuverability and reduce operational costs, making it suitable for long-duration space missions. • A versatile dual-mode space propulsion system with electric pump-fed technology. • Advanced electric pumps enable adjustable thrust and precise control. • Confirmed system feasibility and performance through successful ground tests. • Achieved high efficiency and specific impulse in propulsion engines. • Utilized hydrogen peroxide for eco-friendly, non-toxic propulsion. [ABSTRACT FROM AUTHOR]

[Display omitted] Hydrogen peroxide (H 2 O 2) emerges as a viable oxidant for fuel cells, necessitating the development of an efficient and cost-effective electrocatalyst for the hydrogen peroxide reduction reaction (HPRR). In this study, we synthesized a self-supporting, highly active HPRR electrocatalyst comprising two morphologically distinct components: CeO 2 -NiCo 2 O 4 nanowires and CeO 2 -NiCo 2 O 4 metal organic framework derivatives, via a two-step hydrothermal process followed by air calcination. X-ray diffraction and transmission electron microscopy analysis confirmed the presence of CeO 2 and NiCo 2 O 4 , revealing the amalgamated interface between them. CeO 2 exhibits multifunctionality in regulating the surface electronic configuration of NiCo 2 O 4 , fostering synergistic connections, and introducing oxygen deficiencies to enhance the catalytic efficacy in HPRR. Electrochemical measurements demonstrate a reduction current density of 789.9 mA·cm−2 at −0.8 V vs. Ag/AgCl. The assembly of direct borohydride-hydrogen peroxide fuel cell (DBHPFC) exhibits a peak power density of 45.2 mW·cm−2, demonstrating durable stability over a continuous operation period of 120 h. This investigation providing evidence that the fabrication of heterostructured catalysts based on CeO 2 for HPRR is a viable approach for the development of high-efficiency electrocatalysts in fuel cell technology. [ABSTRACT FROM AUTHOR]

• Contracting skeletal muscles generate reactive oxygen species (ROS) from several locations with the cell. • Although numerous ROS exist, hydrogen peroxide is recognized as a key ROS player in redox control of biological signaling. • Contraction-induced ROS production triggers signaling pathways regulating mitochondrial biogenesis and the expression of numerous genes expressing mitochondrial proteins and antioxidant enzymes. • Growing data indicate that exercise-induced ROS production is essential to achieve the full benefit of exercise-induced adaptation in skeletal muscles. The discovery that contracting skeletal muscle generates reactive oxygen species (ROS) was first reported over 40 years ago. The prevailing view in the 1980s was that exercise-induced ROS production promotes oxidation of proteins and lipids resulting in muscle damage. However, a paradigm shift occurred in the 1990s as growing research revealed that ROS are signaling molecules, capable of activating transcriptional activators/coactivators and promoting exercise-induced muscle adaptation. Growing evidence supports the notion that reduction-oxidation (redox) signaling pathways play an important role in the muscle remodeling that occurs in response to endurance exercise training. This review examines the specific role that redox signaling plays in this endurance exercise-induced skeletal muscle adaptation. We begin with a discussion of the primary sites of ROS production in contracting muscle fibers followed by a summary of the antioxidant enzymes involved in the regulation of ROS levels in the cell. We then discuss which redox-sensitive signaling pathways promote endurance exercise-induced muscle adaptation and debate the strength of the evidence supporting the notion that redox signaling plays an essential role in muscle adaptation to endurance exercise training. In hopes of stimulating future research, we highlight several important unanswered questions in this field. [Display omitted] [ABSTRACT FROM AUTHOR]

Atherosclerosis (AS) poses a significant threat to human life and health. However, conventional antiatherogenic medications exhibit insufficient targeting precision and restricted therapeutic effectiveness. Moreover, during the progression of AS, macrophages undergo polarization toward the proinflammatory M1 phenotype and generate reactive oxygen species (ROS) to accelerate the occurrence of inflammatory storms, and ingest excess lipids to form foam cells by inhibiting cholesterol efflux. In our study, we developed a macrophage membrane-functionalized hollow mesoporous manganese dioxide nanomedicine (Col@HMnO2-MM). This nanomedicine has the ability to evade immune cell phagocytosis, enables prolonged circulation within the body, targets the inflammatory site of AS for effective drug release, and alleviates the inflammatory storm at the AS site by eliminating ROS. Furthermore, Col@HMnO2-MM has the ability to generate oxygen autonomously by breaking down surplus hydrogen peroxide generated at the inflammatory AS site, thereby reducing the hypoxic microenvironment of the plaque by downregulating hypoxia-inducible factor (HIF-1α), which in turn enhances cholesterol efflux to inhibit foam cell formation. In an APOE−/− mouse model, Col@HMnO2-MM significantly reduced inflammatory factor levels, lipid storage, and plaque formation without significant long-term toxicity. In summary, this synergistic treatment significantly improved the effectiveness of nanomedicine and may offer a novel strategy for precise AS therapy. [ABSTRACT FROM AUTHOR]

Wound infection is a major factor affecting the speed and quality of wound healing. While hydrogen peroxide (H2O2) is recognized for its antibacterial capacity and facilitation of wound healing, its administration requires careful dosage differentiation. Inappropriately matched dosages can protract the healing of infected wounds. Herein, a calcium peroxide‐based hydrogel (CPO‐Alg hydrogel) is fabricated to enable a biphasic tapered release of H2O2, ensuring robust initial antimicrobial activity followed by sustained promotion of cellular proliferation of wound healing. The design of the hydrogel allowed for the calcium peroxide nanoparticles (CPO NPs) being in two spatial niches within the gel framework. When applied to infectious wounds, CPO NPs with weak constraints are promptly released out of the gel, penetrating into infected regions to serve as antibacterial agents that eliminate bacteria and biofilms at high concentrations. Conversely, the entrapped CPO NPs structurally integrated into the gel remain confined, thus gradually degrading and allowing a mild release of H2O2 through hydrolysis in a moist environment that contributes to the cell growth in the later stage. The CPO‐Alg hydrogel represents an innovative and practical solution for the antimicrobial protection of chronic wounds, offering promising prospects for advancing wound healing. [ABSTRACT FROM AUTHOR]

Ferroptosis has emerged as a promising strategy for cancer treatment. Nevertheless, the efficiency of ferroptosis-mediated therapy remains a challenge due to high glutathione (GSH) levels and insufficient endogenous hydrogen peroxide in the tumor microenvironment. Herein, we presented a nitric-oxide (NO) boost-GSH depletion strategy for enhanced ferroptosis therapy through a multifunctional nanoplatform with near-infrared (NIR) triggered NO release. The nanoplatform, IS@ATF, was designed that self-assembled by loading the NO donor L-arginine (L-Arg), ferroptosis inducer sorafenib (SRF), and indocyanine green (ICG) onto tannic acid (TA)-Fe3+‒metal-phenolic networks (MPNs) modified with hydroxyethyl starch. Inside the tumor, SRF could inhibit GSH biosynthesis, impair the activation of glutathione peroxidase 4, and disrupt the ferroptosis defensive system. In conjunction with TA-Fe3+‒MPNs, which has cascaded Fenton catalytic activity, it could navigate the lethal ferroptosis to cancer cells. Upon NIR laser irradiation, the ICG-generated ROS oxidated L-Arg to a substantial quantity of NO, which further depleted the intracellular GSH and caused LPO accumulation, enhancing cell ferroptosis. Moreover, ICG also serves as a photothermal agent that can produce hyperthermia when exposed to irradiation, further potentiating ferroptosis therapy. In addition, the nanoplatform showed significantly improved tumor therapeutic efficacy and anti-metastasis efficiency. This work thus demonstrated that utilizing NO boost-GSH depletion to enhance ferroptosis induction is a feasible and promising strategy for cancer treatment. [ABSTRACT FROM AUTHOR]

Developing efficient electrocatalysts for acidic electrosynthesis of hydrogen peroxide (H2O2) holds considerable significance, while the selectivity and stability of most materials are compromised under acidic conditions. Herein, we demonstrate that constructing amorphous platinum–selenium (Pt–Se) shells on crystalline Pt cores can manipulate the oxygen reduction reaction (ORR) pathway to efficiently catalyze the electrosynthesis of H2O2 in acids. The Se2‒Pt nanoparticles, with optimized shell thickness, exhibit over 95% selectivity for H2O2 production, while suppressing its decomposition. In flow cell reactor, Se2‒Pt nanoparticles maintain current density of 250 mA cm−2 for 400 h, yielding a H2O2 concentration of 113.2 g L−1 with productivity of 4160.3 mmol gcat−1 h−1 for effective organic dye degradation. The constructed amorphous Pt–Se shell leads to desirable O2 adsorption mode for increased selectivity and induces strain for optimized OOH* binding, accelerating the reaction kinetics. This selenization approach is generalizable to other noble metals for tuning 2e‒ ORR pathway. Developing efficient catalysts for acidic electrosynthesis of H2O2 is desirable, while most materials are compromised in acidic conditions. Here, the authors report that constructing amorphous Pt–Se shells on crystalline Pt cores can regulate the reaction pathway to efficiently produce H2O2 in acid. [ABSTRACT FROM AUTHOR]

Background: Quinic acid (QA), a cyclitol and cyclohexanecarboxylic acid, is a natural product that is present and can be isolated from edible herbals like tea, coffee and several fruits and vegetables. It was previously reported that QA exerted antioxidant and neuroprotective activity against dementia. However, it was not tested for its neuroprotective potential against Huntington's disease (HD). Since aging related disorders are greatly linked to oxidative stress conditions, we focused on testing the oxidative stress resistant activity and protective effect of QA against the development of HD by using the multicellular Caenorhabditis elegans (C. elegans) worm model. Methods: Firstly, QA was tested for its oxidative stress resistant properties. In survival assay, wild type and mutant skn-1 and daf-16 worms were exposed to oxidative stress conditions by using H2O2. Activation of SKN-1 pathway and expression of its downstream genes gcs-1 and gst-4 were also tested. Secondly, the effect of QA was evaluated on HD by testing its ability to decrease the formation of polyQ150 aggregates. Furthermore, its effect on the accumulation of polyglutamine (polyQ35 and polyQ40 aggregates) was tested. Results: Here we report that QA could improve the survival of C. elegans after exposure to oxidative stress caused by H2O2 while also exerting antioxidant effects through the activation of SKN-1/Nrf2 pathway. Moreover, QA could be a potential candidate to protect against HD due to its effects on decreasing the formation of polyQ150, polyQ35 and polyQ40 aggregates. Conclusions: This study highlights the importance of QA as a natural compound in defending against oxidative stress and the development of neurodegenerative diseases like HD. [ABSTRACT FROM AUTHOR]

Supramolecular polymers possess great potential in catalysis owing to their distinctive molecular recognition and dynamic crosslinking features. However, investigating supramolecular electrocatalysts with high efficiency in oxygen reduction reaction to hydrogen peroxide (ORHP) remains an unexplored frontier. Herein, we present organic polymers for ORHP by introducing cyclodextrin-containing noncovalent building blocks, affording these supramolecules with abundant dynamic bonds. The electronic states and reaction kinetics are further well-modulated via a host-guest strategy, resulting in appropriate regional electron binding force and controllable chemical activity. Notably, integrating supramolecular units into phenyl group-containing model covalent polymer achieves a production rate of 9.14 mol g−1cat h−1, with 98.01% Faraday efficiency, surpassing most reported metal-free electrocatalysts. Moreover, the dynamic bonds in supramolecular catalysts can effectively regulate the binding ability of oxygen intermediates, leading to high reactivity and selectivity for the 2e− pathway. Supported by theory calculation and in situ experiment, C atoms (site–1) adjacent to the –C = N (N) group are potential active sites. This work pioneers host-guest strategy and provides inspiring ideas for the ORHP process. Dynamic bonds offer unique advantages of adaptability and selectivity, yet, supramolecular electrocatalysts specifically tailored for 2e− pathway remain unexplored. Here, the authors report a host-guest strategy that employs dynamic bonds to adjust electronic states through dual-channel regulation. [ABSTRACT FROM AUTHOR]

Background: Hydrogen peroxide (H2O2), a novel water treatment agent, can be used for disinfection, water quality adjustment, and disease prevention, while excessive H2O2 can injure farm animals, even leading to death. Hydrogen peroxide is a recommended disinfectant and bactericide for treating gill diseases and vibriosis in the greenfin horse-faced filefish Thamnaconus septentrionalis. However, its cumulative effect, toxic molecular mechanism and relevant signal transduction/metabolic networks in marine fishes are largely unknown. Results: We employed a multi-omics approach to investigate the detrimental effects of 50 mg/L H2O2 exposure (2 h/d) on filefish for 2 d, 4 d, and 6 d. Transcriptome sequencing showed that differentially expressed genes (DEGs) were mainly classified into functions such as signal transduction, nervous system, liver and bile acid metabolism, energy metabolism, cell adhesion and communication, inflammation and immune response. Metabolomic analysis found that the significantly changed metabolites (SCMs) were involved in phenylalanine metabolism, inflammatory mediator regulation, linoleic acid metabolism, and necroptosis. The main SCMs were cholic acid, carnitine C12:1, dimethylmalonic acid, glutamic acid, L-lactic acid, shikimic acid, 2-methylsuccinic acid, and others. Moreover, H2O2-induced oxidative stress also disturbs the balance of the gut microbiota, altering the microbial composition and affecting digestive processes. Conclusions: Integrated multiomics analysis revealed that H2O2-induced detrimental impacts include mucosal damage, inflammatory and immune responses, altered energy metabolism, and gut microbiota disorders. These findings offer novel insights into the harmful effects and signal transduction/metabolic pathways triggered by H2O2 exposure in marine fishes. [ABSTRACT FROM AUTHOR]

Aerobic organisms continuously generate internal superoxide and hydrogen peroxide, which can damage enzymes and impair growth. To avoid this problem cells maintain high levels of superoxide dismutases, catalases, and peroxidases. Surprisingly, we do not know the primary sources of these reactive oxygen species (ROS) in living cells. However, in vitro studies have shown that flavoenzymes can inadvertently transfer electrons to oxygen. Therefore, it seems plausible that substantial ROS may be generated when large metabolic fluxes flow through flavoproteins. Such a situation may arise during the catabolism of fatty acids. Acyl-CoA dehydrogenase (FadE) is a flavoprotein involved in each turn of the beta-oxidation cycle. In the present study the catabolism of dodecanoic acid specifically impaired the growth of strains that lack enzymes to scavenge hydrogen peroxide. The defect was absent from fadE mutants. Direct measurements confirmed that the beta-oxidation pathway amplified the rate of intracellular hydrogen peroxide formation. Scavenging-proficient cells did not display the FadE-dependent growth defect. Those cells also did not induce the peroxide stress response during dodecanoate catabolism, indicating that the basal defenses are sufficient to cope with moderately elevated peroxide formation. In vitro work still is needed to test whether the ROS evolve specifically from the FadE flavin site and to determine whether superoxide as well as peroxide is released. At present such experiments are challenging because the natural redox partner of FadE has not been identified. This study supports the hypothesis that the degree of internal ROS production can depend upon the type of active metabolism inside cells. [ABSTRACT FROM AUTHOR]

Human fungal pathogens must survive diverse reactive oxygen species (ROS) produced by host immune cells that can oxidize a range of cellular molecules including proteins, lipids, and DNA. Formation of lipid radicals can be especially damaging, as it leads to a chain reaction of lipid peroxidation that causes widespread damage to the plasma membrane. Most previous studies on antioxidant pathways in fungal pathogens have been conducted with hydrogen peroxide, so the pathways used to combat organic peroxides and lipid peroxidation are not well understood. The most well-known peroxidase in Candida albicans, catalase, can only act on hydrogen peroxide. We therefore characterized a family of four glutathione peroxidases (GPxs) that were predicted to play an important role in reducing organic peroxides. One of the GPxs, Gpx3 is also known to activate the Cap1 transcription factor that plays the major role in inducing antioxidant genes in response to ROS. Surprisingly, we found that the only measurable role of the GPxs is activation of Cap1 and did not find a significant role for GPxs in the direct detoxification of peroxides. Furthermore, a CAP1 deletion mutant strain was highly sensitive to organic peroxides and oxidized lipids, indicating an important role for antioxidant genes upregulated by Cap1 in protecting cells from organic peroxides. We identified GLR1 (Glutathione reductase), a gene upregulated by Cap1, as important for protecting cells from oxidized lipids, implicating glutathione utilizing enzymes in the protection against lipid peroxidation. Furthermore, an RNA-sequencing study in C. albicans showed upregulation of a diverse set of antioxidant genes and protein damage pathways in response to organic peroxides. Overall, our results identify novel mechanisms by which C. albicans responds to oxidative stress resistance which open new avenues for understanding how fungal pathogens resist ROS in the host. Author summary: Human fungal pathogens must survive attack by diverse reactive oxygen species (ROS) produced by host immune cells in order to cause a lethal disseminated infection. This oxidative stress damages many different cellular molecules including proteins, lipids, and DNA. Fungal plasma membrane lipids are one of the first targets to encounter this oxidative damage, so our studies focused on identifying the antioxidant pathways in the human fungal pathogen Candida albicans that protect this essential barrier. Furthermore, we included the analysis of organic (carbon-containing) peroxides, which behave differently than the more commonly studied hydrogen peroxide. Our results indicate that resistance to organic peroxides in C. albicans is mediated by the transcription factor Cap1 that induces the expression of a wide array of antioxidant genes. Many genes contribute to resistance to oxidation, but our studies revealed a key role for the Cap1-regulated gene GLR1. Altogether, these results identify novel mechanisms by which C. albicans protects against oxidative stress, which open new avenues for development of novel therapeutic strategies to combat fungal infections. [ABSTRACT FROM AUTHOR]