Peroxidation Products Research Articles

Genetic Characterization of the Glucose-PTS in Streptococcus sanguinis, examining competitive fitness.

Ecological shifts in dental microbiome from homeostasis to dysbiosis have been hypothesized to underlie several oral diseases including dental caries. Streptococcus sanguinis, a commensal bacterium, is pivotal in maintaining oral health through its metabolic activities, including the production of ammonia and hydrogen peroxide (H2O2). This study aims to elucidate the genetic underpinnings of the glucose::phosphotransferase system (PTS) in the physiology and competitive fitness of S. sanguinis within the oral microbiome, by examining single nucleotide polymorphisms (SNPs) in the EIIABMan (manL) and HPr of PTS in S. sanguinis strain SK36. Employing genetic engineering, bioinformatic analysis, growth and metabolic assays, recreating and characterizing several unique ManL SNPs in SK36 that were identified among clinical strains of S. sanguinis. Mutations in ManL and HPr correlated with altered growth dynamics, H2O2 production, acid production, and pH homeostasis in a manner uncoupled from canonical regulators such as CcpA and Rex. These genetic variations likely contributed to S. sanguinis's competitiveness, although their ecological impact remains to be further elucidated. This research is part of the ongoing effort to understand the genetic mechanisms that contribute to microbial ecology in relation to health, knowledge from which may allow for enhanced diagnostics, pro-health formulations, and other microbial interventions.

Exfoliated Porous Carbon Nitride by Simultaneous Oxidation-Corrosion for Photocatalytic H2O2 Production and Organic Degradation.

Graphitic carbon nitride (g-C3N4) is a fascinating material with potential applications in photocatalysis due to its good chemical stability, high thermal stability, and relative ease of synthesis. In this work, ultrathin g-C3N4 is constructed using a hybridized method, which combines the advantages of thermal and liquid-phase stripping methods. This sample can improve performance in degrading organic pollutants several times, and the highest enhancement efficiency occurs in an alkaline environment. In addition, photocatalytic production of hydrogen peroxide can be increased to 2.6 times that of the bulk sample. These improved properties are due to the increase in specific surface area, the generation of free radicals, and adsorption capacity. This work presents a one-step exfoliation method for bulk g-C3N4 for more surface-active sites and strong redox capacity.

Azobenzene-Bridged Covalent Organic Frameworks Boosting Photocatalytic Hydrogen Peroxide Production from Alkaline Water: One Atom Makes a Significant Improvement.

Covalent organic frameworks (COFs) have been demonstrated as promising photocatalysts for hydrogen peroxide (H2O2) production. However, the construction of COFs with new active sites, high photoactivity, and wide-range light absorption for efficient H2O2 production remains challenging. Herein, we present the synthesis of a novel azobenzene-bridged 2D COF (COF-TPT-Azo) with excellent performance on photocatalytic H2O2 production under alkaline conditions. Notably, although COF-TPT-Azo differs by only one atom (-N=N- vs. -C=N-) from its corresponding imine-linked counterpart (COF-TPT-TPA), COF-TPT-Azo exhibits a significantly narrower band gap, enhanced charge transport, and prompted photoactivity. Remarkably, when employed as a metal-free photocatalyst, COF-TPT-Azo achieves a high photocatalytic H2O2 production rate up to 1498 μmol g-1 h-1 at pH = 11, which is 7.9 times higher than that of COF-TPT-TPA. Further density functional theory (DFT) calculations reveal that the -N=N- linkages are the active sites for photocatalysis. This work provides new prospects for developing high-performance COF-based photocatalysts.

Azobenzene‐Bridged Covalent Organic Frameworks Boosting Photocatalytic Hydrogen Peroxide Production from Alkaline Water: One Atom Makes a Significant Improvement

AbstractCovalent organic frameworks (COFs) have been demonstrated as promising photocatalysts for hydrogen peroxide (H2O2) production. However, the construction of COFs with new active sites, high photoactivity, and wide‐range light absorption for efficient H2O2 production remains challenging. Herein, we present the synthesis of a novel azobenzene‐bridged 2D COF (COF‐TPT‐Azo) with excellent performance on photocatalytic H2O2 production under alkaline conditions. Notably, although COF‐TPT‐Azo differs by only one atom (−N=N− vs. −C=N−) from its corresponding imine‐linked counterpart (COF‐TPT‐TPA), COF‐TPT‐Azo exhibits a significantly narrower band gap, enhanced charge transport, and prompted photoactivity. Remarkably, when employed as a metal‐free photocatalyst, COF‐TPT‐Azo achieves a high photocatalytic H2O2 production rate up to 1498 μmol g−1 h−1 at pH = 11, which is 7.9 times higher than that of COF‐TPT‐TPA. Further density functional theory (DFT) calculations reveal that the −N=N− linkages are the active sites for photocatalysis. This work provides new prospects for developing high‐performance COF‐based photocatalysts.

Three‐Dimensional Covalent Organic Frameworks Based on Linear and Trigonal Linkers for High‐Performance H2O2 Photosynthesis

AbstractThe design of three‐dimensional covalent organic frameworks (3D COFs) using linear and trigonal linkers remains challenging due to the difficulty in achieving a specific non‐planar spatial arrangement with low‐connectivity building units. Here, we report the novel 3D COFs with linear and trigonal linkers, termed TMB‐COFs, exhibiting srs topology. The steric hindrance provides an additional force to alter the torsion angles of peripheral triangular units, guiding the linear unit to connect with the trigonal unit into 3D srs frameworks, rather than the more commonly observed two‐dimensional (2D) hcb structures. Furthermore, we comprehensively examined the hydrogen peroxide photocatalytic production capacity of the TMB‐COFs in comparison with analogous 2D COFs. The experimental results and DFT calculations demonstrate a significant enhancement in photocatalytic hydrogen peroxide production efficacy through framework regulation. This work emphasizes the steric configuration using low connectivity building units, offering a fresh perspective on the design and application of 3D COFs.

Modulating Yeager Adsorption Configuration of O2 Through Cd Doping in Zn3In2S6 for Photosynthesis of H2O2

AbstractThe photocatalytic oxygen reduction reaction (ORR) is a key pathway for producing hydrogen peroxide (H2O2). While most previous studies have focused on the two‐step 2e− ORR process, the one‐step two‐electron ORR route offers thermodynamic and kinetic advantages that can significantly enhance 2e− ORR activity and selectivity. In this study, a photocatalyst design is reported by incorporating cadmium into vacancy‐rich Zn3In2S6 (Cd‐SV/ZIS). This catalyst enables H2O2 production via a one‐step 2e− ORR process without the use of sacrificial agents, achieving a high H2O2 yield of 39.42 µmol g−1 min−1 under UV–vis light irradiation, outperforming most reported ZIS‐based photocatalysts. Theoretical simulations and experimental results demonstrate that Cd doping improves the carrier kinetics of the catalyst, broadens its light absorption range, and promotes the Yeager adsorption configuration of O2, leading to highly active and selective H2O2 generation. This study provides insights into the design of efficient ZIS‐based photocatalysts for H2O2 production.

Lipid peroxidation products induce carbonyl stress, mitochondrial dysfunction, and cellular senescence in human and murine cells.

Lipid enals are electrophilic products of lipid peroxidation that induce genotoxic and proteotoxic stress by covalent modification of DNA and proteins, respectively. As lipid enals accumulate to substantial amounts in visceral adipose during obesity and aging, we hypothesized that biogenic lipid enals may represent an endogenously generated, and therefore physiologically relevant, senescence inducers. To that end, we identified that 4-hydroxynonenal (4-HNE), 4-hydroxyhexenal (4-HHE) or 4-oxo-2-nonenal (4-ONE) initiate the cellular senescence program of IMR90 fibroblasts and murine adipose stem cells. In such cells, lipid enals induced accumulation of γH2AX foci, increased p53 signaling, enhanced expression of p21Cip1, and upregulated the expression and secretion of numerous cytokines, chemokines, and regulatory factors independently from NF-κB activation. Concomitantly, lipid enal treatment resulted in covalent modification of mitochondrial proteins, reduced mitochondrial spare respiratory capacity, altered nucleotide pools, and increased the phosphorylation of AMP kinase. Lipid-induced senescent cells upregulated BCL2L1 (Bcl-xL) and BCL2L2 (Bcl-w). and were resistant to apoptosis while pharmacologic inhibition of BAX/BAK macropores attenuated lipid-induced senescence. Insitu, the 4-HNE scavenger L-carnosine ameliorated the development of the cellular senescence, while in visceral fat of obese C57BL/6J mice, L-carnosine reduced the abundance of 4-HNE-modified proteins and blunted the expression of senescence biomarkers CDKN1A (p21Cip1), PLAUR, BCL2L1, and BCL2L2. Taken together, the results suggest that lipid enals are endogenous regulators of cellular senescence and that biogenic lipid-induced senescence (BLIS) may represent a mechanistic link between oxidative stress and age-dependent pathologies.

Deubiquitylase USP52 Promotes Bladder Cancer Progression by Modulating Ferroptosis through Stabilizing SLC7A11/xCT.

Bladder cancer (BLCA) is a prevalent cancer with high case-fatality rates and a substantial economic burden worldwide. Understanding its molecular underpinnings to guide clinical management is crucial. Ferroptosis, a recently described non-apoptotic form of cell death, is initiated by the lethal accumulation of iron-dependent lipid peroxidation products. Despite growing interest, the roles and vulnerabilities determining ferroptosis sensitivity in BLCA remain unclear. Re-analysis of single-cell RNA data reveals a decrease in high-ferroptosis cancer cells as BLCA advances. USP52/PAN2 is identified as a key regulator of ferroptosis in BLCA through an unbiased siRNA screen targeting 96 deubiquitylases (DUBs). Functionally, USP52 depletion impedes glutathione (GSH) synthesis by promoting xCT protein degradation, increasing lipid peroxidation and ferroptosis susceptibility, thus suppressing BLCA progression. Mechanistically, USP52 interacts with xCT and enzymatically cleaves the K48-conjugated ubiquitin chains at K4 and K12, enhancing its protein stability. Clinical BLCA samples demonstrate a positive correlation between USP52 and xCT expression, with high USP52 levels associated with aggressive disease progression and poor prognosis. In vivo, USP52 depletion combined with ferroptosis triggers imidazole ketone Erastin (IKE) synergistically restrains BLCA progression by inducing ferroptosis. These findings elucidate the role of the USP52-xCT axis in BLCA and highlight the therapeutic potential of targeting USP52 and ferroptosis inducers in BLCA.

Level of prooxidant-antioxidant status in highly productive cows with comorbid obstetric, gynecological and orthopedic pathology

The lipid peroxidation and antioxidant defense system is a balanced system responsible for the processing and utilization of lipids in the body’s cells. It plays an important role in lipid metabolism, cell protection and overall health of the body. Its proper functioning is necessary to ensure optimal functioning of cells and organs throughout the body. The article clinically and experimentally substantiates the pathogenetic role of lipid peroxidation products and the level of antioxidant protection in cows with endometritis and purulent-necrotic processes in the finger area, as well as with the comorbid course of endometritis and orthopedic pathology. It has been shown that multimorbid manifestation is accompanied by a more severe course than individual diseases. It has been established that the development of postpartum endometritis and purulent-necrotic lesions of the limbs in cows is accompanied by a highly significant increase in lipid peroxidation products in the blood serum against the background of a decrease in the amount of antioxidant enzymes, with the exception of ceruloplasmin. Moreover, these changes are accompanied by a sharp jump in the comorbid course of endometritis and orthopedic pathology in highly productive animals.

Facile preparation of Co-doped ZnIn2S4 nanosheets for highly efficient photocatalytic hydrogen peroxide production

Utilizing solar energy to produce hydrogen peroxide from oxygen and water offers an appealing and sustainable approach. In this work, Co-doped ZnIn2S4 nanosheets were effectively synthesized through a chemical precipitation method, and the morphological structure, band structure and pathways for hydrogen peroxide production were investigated. The results indicate that Co doping significantly enhances the photocatalytic efficiency of ZnIn2S4 in producing hydrogen peroxide. The sample with the 2 % doping concentration exhibited the highest rate, with a detected hydrogen peroxide concentration of 535.53 µM in the solution after 100 minutes of exposure to visible light, which is 4.29-fold higher than that of undoped ZnIn2S4. Further analysis revealed that the improved performance mainly originated from better spectral response, faster photogenerated carrier transport, and lower recombination frequency of photogenerated electron-hole pairs.

Spontaneous Production of H2O2 at the Liquid-Ice Interface: A Potential Source of Atmospheric Oxidants.

We present experimental evidence for the spontaneous production of hydrogen peroxide (H2O2) at the liquid-ice interface during the freezing of dilute salt solutions. Specifically, sample solutions containing NaCl, NaBr, NH4Cl, and NaI at concentrations between 10-6 and 10-1 M were subjected to freezing-melting cycles and then analyzed for H2O2 content. The relationship between the production rate of H2O2 and the salt concentration follows that of the Workman-Reynolds freezing potential (WRFP) values as a function of the salt concentration. Our results suggest that H2O2 is formed at the liquid-ice interface from the self-recombination of hydroxyl radicals (OH·), produced from the oxidation of hydroxide anions due to the high electric field generated at the aqueous-ice interface under the WRFP effect. Furthermore, the involvement of O2 likely acting as an electron capturer could promote to produce more OH radicals and hydroperoxyl radicals (HO2·), thus enhancing the production of H2O2 at the liquid-ice interface. Overall, this study suggests a novel mechanism of H2O2 formation in ice via its spontaneous production at the liquid-ice interface, induced by the Workman-Reynolds effect.

Tumor integrin-targeted glucose oxidase enzyme promotes ROS-mediated cell death that combines with interferon alpha therapy for tumor control.

While heightened intratumoral levels of reactive oxygen species (ROS) are typically associated with a suppressive tumor microenvironment, under certain conditions ROS contribute to tumor elimination. Treatment approaches, including some chemotherapy and radiation protocols, increase cancer cell ROS levels that influence their mechanism of cell death and subsequent recognition by the immune system. Furthermore, activated myeloid cells rapidly generate ROS upon encounter with pathogens or infected cells to eliminate disease, and recently, this effector function has been noted in cancer contexts as well. Collectively, ROS-induced cancer cell death may help initiate adaptive anti-tumor immune responses that could synergize with current approved immunotherapies, for improved control of solid tumors. In this work, we explore the use of glucose oxidase, an enzyme which produces hydrogen peroxide, a type of ROS, to therapeutically mimic the endogenous oxidative burst from myeloid cells to promote antigen generation within the tumor microenvironment. We engineer the enzyme to target pan-tumor expressed integrins both as a tumor-agnostic therapeutic approach, but also as a strategy to prolong local enzyme activity following intratumoral administration. We found the targeted enzyme potently induced cancer cell death and enhanced cross-presentation by dendritic cells in vitro, and further combined with interferon alpha for long-term tumor control in murine MC38 tumors in vivo. Optimizing the single-dose administration of this enzyme overcomes limitations with immunogenicity noted for other pro-oxidant enzyme approaches. Overall, our results suggest ROS-induced cell death can be harnessed for tumor control, and highlight the potential use of designed enzyme therapies alongside immunotherapy against cancer.

Constructing boosted charge separation for efficient H2O2 production and pollutant degradation by highly defective ZnIn2S4/ carbon doped boron nitride

Solar-driven photocatalytic production of H2O2 as a promising environmentally-friendly approach has been applied as a chemical reagent and for enhancing photocatalytic remediation. However, this process is still limited by unsatisfactory efficiency and hard separation of photogenerated charge carriers. Herein, we design a dual pathway to improve hydrogen peroxide production by establishing a 2D/2D heterojunction between carbon-doped boron nitride (BCN) and defective zinc indium sulfide (ZIS). The introduction of multiple vacancies and dopants at the interface successfully promoted the interfacial charge transfer and peroxide generation. The Z-scheme heterojunction establishes a built-in electronic field, facilitating continuous electron accumulation and depletion, thereby inducing band bending. As a result, the optimized BCN/ZIS-30 composite (>420 nm wavelength) exhibits 925 μmol/g/h in pure water with no other additions and advances this production to 2006.1 μmol/g/h (2 times as defective ZIS and 12.1 times as BCN) under the existence of isopropanol and aeration. Mechanism investigation indicated that H2O2 is generated via a two-step electron reduction route and water oxidation reaction. The generated H2O2 successfully constructs a self-photo-Fenton system by forming hydroxyl radicals. Accompanied by strong oxygen activation ability, the photo-Fenton system also exhibits rapid degradation of antibiotics with 95 % elimination in 60 minutes. The practical applicability of this photocatalyst was demonstrated through real water remediation tests, exhibiting its effectiveness in removing antibiotics, COD, and total ammonia nitrogen, highlighting its potential for practical water treatment applications. This work provides a novel idea on constructing heterojunction materials for energy saving and water remediation.

Extension of Vase Life by Nano-Selenium in Rosa hybrida

Vase life directly affects the ornamental value of cut flowers, and extending vase life has been a research focus in the floriculture industry. The antioxidant and antimicrobial properties of Nano-Se provide a new direction to extend the life of cut-flower vase life. In order to explore the postharvest quality of Nano-Se on cut-flower roses, this study treated cut-flower roses with different concentrations of Nano-Se (200, 400, and 600 mM) using a commercially available preservative solution as a base solution. The results showed that appropriate concentrations of Nano-Se significantly increased the vase life of cut-flower roses and helped to maintain high petal moisture content. Nano-Se at concentrations of 200, 400, and 600 mM extended the vase life of cut roses by 4.3, 5.7, and 3.7 d, respectively. As the vase period extended, the Nano-Se treatment group effectively delayed the decline in antioxidant enzyme activities such as peroxidase (POD) and catalase (CAT), maintained the soluble sugar (SS) and soluble protein (SP) contents in the cut roses, and inhibited the production of malondialdehyde (MDA) and hydrogen peroxide (H2O2), reducing their accumulation. A correlation analysis of the physiological indexes of cut roses showed that vase life was positively correlated with POD and CAT activities, SS and SP contents, and total phenolic acid content and negatively correlated with MDA and H2O2 contents. This study provides a solid theoretical basis for the diversification of preservatives and the development of new preservatives for fresh-cut roses, which is expected to provide significant economic benefits.

Enzymatic Synthesis of Isotopically Labeled Hydrogen Peroxide for Mass Spectrometry-Based Applications.

Methionine oxidation is involved in multiple biological processes including protein misfolding and enzyme regulation. However, it is often challenging to measure levels of methionine oxidation by mass spectrometry, in part due to the prevalence of artifactual oxidation that occurs during the sample preparation and ionization steps of typical proteomic workflows. Isotopically labeled hydrogen peroxide (H218O2) can be used to block unoxidized methionines and enables accurate measurement of in vivo levels of methionine oxidation. However, H218O2 is an expensive reagent that can be difficult to obtain from commercial sources. Here, we report a method for synthesizing H218O2 in-house. Glucose oxidase catalyzes the oxidation of β-d-glucose and produces hydrogen peroxide in the process. We took advantage of this reaction to enzymatically synthesize H218O2 from 18O2 and assessed its concentration, purity, and utility in measuring methionine oxidation levels by mass spectrometry.

Study of Exhaust Gas Composition and Dilution Effects on Diesel Spray Ignition Characteristics

ABSTRACT Exhaust gas retained in a cylinder is unavoidable, affecting diesel spray ignition. However, its effects on diesel spray ignition characteristics are not completely clear so far, due to the coupled and complicated function of exhaust gas compositions and dilution effects. To reveal the effect mechanism, three-dimensional simulations and chemical kinetics calculations were performed. The results illustrate that with the rise of exhaust gas rate, the initial position of the flame moves downward due to the longer ignition delay. The introduction of exhaust gas compositions decreases both the low-temperature and high-temperature ignition delay while dilution on oxygen mass fraction primarily affects and prolongs the high-temperature ignition delay. Nitric oxide (NO) significantly decreases the ignition delay compared to other exhaust gas compositions, with the high-temperature ignition delay experiencing a substantial decrease of 33.33% under 500 ppm NO addition at the ambient temperature of 820K. With the NO addition in the fresh intake air, conversion reactions occur between NO and nitrogen dioxide, and the reactions of NO with hydroperoxyl (HO2) and nitrogen dioxide with hydrogen radical lead to the generation of hydroxyl radical throughout the low- and high-temperature ignition stages, which enhances system reactivity and contributes to a decrease of ignition delay. The decrease in the oxygen mass fraction significantly reduces the rate of production of HO2 and hydrogen peroxide, which results in a decrease in the rate of production of hydrogen peroxide decomposition and HO2 deoxidation into hydroxyl radicals, prolonging the high-temperature ignition. The revealed mechanism may be applicable to the diagnosis of exhaust gas residual fault phenomenon.

Callose and Salicylic Acid Are Key Determinants of Strigolactone-Mediated Disease Resistance in Arabidopsis

Research has demonstrated that strigolactones (SLs) mediate plant disease resistance; however, the basal mechanism is unclear. Here, we provide key genetic evidence supporting how SLs mediate plant disease resistance. Exogenous application of the SL analog, rac-GR24, increased Arabidopsis thaliana resistance to virulent Pseudomonas syringae. SL-biosynthetic mutants and overexpression lines of more axillary growth 1 (MAX1, an SL-biosynthetic gene) enhanced and reduced bacterial susceptibility, respectively. In addition, rac-GR24 promoted bacterial pattern flg22-induced callose deposition and hydrogen peroxide production. SL-biosynthetic mutants displayed reduced callose deposition but not hydrogen peroxide production under flg22 treatment. Moreover, rac-GR24 did not affect avirulent effector-induced cell death between Col-0 and SL-biosynthetic mutants. Furthermore, rac-GR24 increased the free salicylic acid (SA) content and significantly promoted the expression of pathogenesis-related gene 1 related to SA signaling. Importantly, rac-GR24- and MAX1-induced bacterial resistance disappeared completely in Arabidopsis plants lacking both callose synthase and SA. Taken together, our data revealed that callose and SA are two important determinants in SL-mediated plant disease resistance, at least in Arabidopsis.

Alkali metal cation adsorption–induced surface polarization in polymeric carbon nitride for enhanced photocatalytic hydrogen peroxide production

Photocatalytic hydrogen peroxide (H2O2) generation on the catalyst surface from oxygen is an electron-demanding process, making the construction of an electron-rich surface highly advantageous. In this study, a localized electric field was observed on the surface of polymeric carbon nitride (g-C3N4) when alkali metal cations were adsorbed onto it. These fields effectively inhibited surface carrier recombination and extended their lifespan, thereby enhancing H2O2 production. As a result, g-C3N4 achieved a superior H2O2 yield of 2.25 mM after 1 h in a 0.25 M K+ solution, which was 2.06 times greater than that (1.09 mM) achieved in a pure solvent. Notably, the increase in photocatalytic efficiency showed a remarkable dependence on ion species. At low concentrations, H2O2 generation efficiency was in the order of Li+ < Na+ < K+ < Rb+ < Cs+. However, after optimizing the ion concentration, the highest H2O2 production was achieved in a solution containing K+ instead of Cs+. Molecular dynamics simulations and temperature-dependent photocatalysis experiments revealed that the synergistic interaction between adsorption energy and adsorption distance was crucial in governing the extent to which alkali metal cation adsorption enhanced g-C3N4 photocatalytic H2O2 production. This study provides theoretical insights for the design of materials for electron-demanding photocatalysis and aids in understanding variations in photocatalytic behavior in natural waters.

Synergistic regulation of g-C3N4 band structure by phosphorus and sodium doping to enhance photocatalytic hydrogen peroxide production efficiency

In addressing the industrial need for a simple, equipment-minimal, and non-toxic method of in-situ hydrogen peroxide (H2O2) production, this paper presents a cost-effective, environmentally friendly photocatalyst. Our design strategy focuses on the dual-element doping of phosphorus and sodium into graphitic carbon nitride (g-C3N4), chosen to synergistically enhance photocatalytic performance. This approach yields a notable H2O2 production concentration of 3001.64 μmol·g−1·L-1 within 100 min, using isopropanol as a sacrificial agent, which was 61-fold increase compared to bulk g-C3N4. Density Functional Theory (DFT) calculations were performed to elucidate the alterations in the band structure of the catalyst induced by dual-element doping, which consequentially engendered an asymmetric intrinsic electric field. Additionally, oxygen’s transition state affinity due to phosphorus doping was also investigated to reveal the mechanisms of synergistic catalysis. This development contributes to meeting industrial demands for pollutant degradation via Fenton processes and presents a sustainable alternative to traditional H2O2 production methods.

The Role of Arginase and some Parameters in Diabetic Type 2 Patients with and without Retinopathy

Background: Oxidative stress plays a major role in the pathogenesis of diabetes mellitus by damaging cellular organelles and enzymes in blood such as arginase1, insulin and glutathione s-transferase; increasing lipid peroxidation such as malondialdehyde and increasing insulin resistance which can lead to diabetic complications such as diabetic retinopathy. Objectives: To explore the relationship of oxidative stress to the development of diabetic retinopathy by measuring the levels of Arginase1, the activity of glutathione s-transferase enzyme, and the levels of malondialdehyde as a secondary product of lipid peroxidation (biomarker for oxidative stress). Patients and MethodsThis study was conducted from November 2022 to January 2023 at the Ibn Al-Haitham Teaching Eye Hospital in Baghdad, the University of Baghdad / Department of Chemistry and the National Diabetes Centre for Treatment and Research at Al-Mustansyrriah University. This study was conducted on 120 subjects distributed as follows: 40 non-diabetic obese controls, 40 type 2 diabetics with no retinopathy, and 40 type 2 diabetic retinopathy patients, between 30 and 65 years of age. All groups were subjected to tests: measuring fasting blood glucose (FBG), HbA1c, lipid profile (cholesterol, triglycerides, HDL- cholesterol, LDL- cholesterol, and VLDL cholesterol), serum total arginase1, malondialdehyde glutathione s -transferase, body mass index (BMI), and waist-to-hip ratio. Results: Mean arginase1 levels were significantly higher in diabetic patients than in diabetic retinopathy and control groups (p ≤ 0.05). The mean xidative stress marker malondialdehyde concentration was significantly higher in diabetic retinopathy patients than in type 2 diabetics and the control group (P ≤ 0.05). The mean glutathione s-transferase activity in diabetic retinopathy patients was significantly higher than in the control group and type 2 diabetics (P ≤ 0.05). Conclusion: There is a relationship between oxidative stress and the development of diabetic retinopathy, where the levels of arginase1 and malondialdehyde increased and the activity of glutathione s –transferase enzyme increased as a result of oxidative stress and inflammation associated with complications of type 2 diabetes.