OH Scavenger Research Articles

Chemical Composition and Biological Activity of Hypericum Species-H. hirsutum, H. barbatum, H. rochelii.

St. John's wort (Hypericum perforatum, Hypericaceae) is the most well-known species in the genus Hypericum, which comprises several hundred species. This study investigates the biological and phytochemical potential of the under-researched Hypericum species, H. hirsutum, H. barbatum, and H. rochelii. A high level of similarity between the chemical profiles of H. hirsutum and H. barbatum and the official source of the herbal drug (H. perforatum) was shown, but a higher content of quercetin and rutin was also found in all three evaluated species (116-230 µg/g dry herb). The highest amount of phenolics (195 mg GAE/g) was recorded in H. hirsutum extract, while the highest amount of flavonoids (47 mg QE/g) was recorded in H. barbatum extract. The evaluated species were excellent scavengers of DPPH, OH, and NO radicals, as well as strong ferric ion reducers in the FRAP test. Prominent monoamine oxidase A and α-glucosidase inhibition was observed, compared to modest inhibition of monoamine oxidase B, α-amylase, and acetylcholinesterase. High activity against Gram-positive MRSA S. aureus was demonstrated for the tested species, with MIC/MBC values recorded at 12.5 µg/mL. Antifungal activity against Candida strains was not observed. The obtained results emphasize the need for further investigation of species of the genus Hypericum to discover potentially new sources of biologically active compounds.

Effect of Ultrahigh Dose Rate on Biomolecular Radiation Damage.

Dose rate is one of the important parameters in radiation-induced biomolecular damage. The effects of dose rate have been known to modify radiation toxicity in biological systems. The rate and extent of sublethal DNA damage (e.g., base damage and single-strand breaks) repair and those of cell proliferation have been manifested by dose rate. However, the recent preclinical application of ultrahigh dose rate [(UHDR) ca. 40 Gy/s and higher] radiation modalities have been shown to lower the type and extent of radiation damage to biological systems. At these UHDR, radiation-induced physicochemical and chemical processes are expected to differ from those observed after irradiation at conventional dose rates (CONV). It is unclear whether these UHDR conditions can affect the quality (type) and quantity (extent) of biomolecular damage such as DNA lesions. Here, we comparatively study the influence of indirect effects of CONV and UHDR on the formation of DNA strand breaks and clustered damage including densely accumulated lesions in an aerated and an anoxic dilute aqueous solution of a plasmid DNA model under low and high hydroxyl radical (•OH) scavenging conditions. Aqueous solutions of purified supercoiled plasmid DNA (pUC19) were prepared in either air- or nitrogen-saturated conditions, with Tris buffer added as the radiation-produced •OH scavenger at low and high scavenging capacities. These DNA samples were irradiated using kV X-ray systems at CONV (0.1 Gy/s) and high dose rate (HDR, 25 Gy/s) as well as UHDR (55 and 125 Gy/s) under different scavenging and environmental conditions. DNA lesions including strand breaks and clustered damage including densely accumulated lesions were quantified by gel electrophoresis and the yields of these lesions were calculated from the dose-response curve. Non-DSB clustered damage including densely accumulated lesions were evaluated by treating DNAs using bacterial endonuclease enzymes (Fpg and Nth) prior to gel electrophoresis. UHDR of 55 and 125 Gy/s induced lower amounts of both isolated strand breaks and clustered DNA damage including densely accumulated lesions at doses >40 Gy in the presence of oxygen, compared to the abundance of these lesions induced by 0.1 and 25 Gy/s irradiation under the same dose conditions. Overall, the strand break and clustered damage including densely accumulated lesions yields decreased by factors of 1.3-3.5 after UHDR. We did not observe these differences either via •OH scavenging or by removing oxygen from the solution. In addition, our results point out that the inter-track recombination reactions did not contribute to the observed dose-rate effects on DNA damage. The effects of dose rate on DNA damage are highly dependent on the total dose, as expected, but also on the •OH scavenging capacity that is employed in the aqueous DNA solutions. These important variables may be relevant in biological systems as well. On a practical level, our in vitro plasmid DNA model, which permits to precisely vary the scavenging capacity and gassing conditions (air saturated vs. N2 saturated) can help to differentiate dose-rate effects on biomolecular damage. Our results indicate that the radical-radical reactions are important in understanding the dose-rate effect on DNA damage.

Preparation, characteristics and antioxidant activity of mung bean peel polysaccharides

The mung bean peel polysaccharide (MBP) extracted by hot water was chemically modified. By changing the dosage of phosphorylation reagent and acetylation reagent, three kinds of phosphorylated MBP ( P-MBP-1, P-MBP-2, P-MBP-3 ) and acetylated MBP ( AC 0.6-MBP, AC 1-MBP, AC 1.4-MBP ) with different degrees of substitution were prepared. By measuring the sugar content and substitution degree of the modified products, it was found that the amount of reagent had a certain effect on both of them. The modified products were determined by infrared spectrum and nuclear magnetic resonance. The results showed that the chemical modification was successful. The in vitro antioxidant capacity (·OH scavenging ability, O2−·clearing ability, reducing capacity, resistance to lipid peroxidation) of seven polysaccharide were measured, which manifested that chemical modification could enhance the antioxidant ability of MBP to varying degrees, and the DS also had a certain impact on their antioxidant activity. This promoted the development of mung bean peel polysaccharide functional products and the utilization of mung bean peel resources.

Orally biomimetic metal-phenolic nanozyme with quadruple safeguards for intestinal homeostasis to ameliorate ulcerative colitis

BackgroundUlcerative colitis (UC) is defined by persistent inflammatory processes within the gastrointestinal tract of uncertain etiology. Current therapeutic approaches are limited in their ability to address oxidative stress, inflammation, barrier function restoration, and modulation of gut microbiota in a coordinated manner to maintain intestinal homeostasis.ResultsThis study involves the construction of a metal-phenolic nanozyme (Cur-Fe) through a ferric ion-mediated oxidative coupling of curcumin. Cur-Fe nanozyme exhibits superoxide dismutase (SOD)-like and •OH scavenging activities, demonstrating significant anti-inflammatory and anti-oxidant properties for maintaining intracellular redox balance in vitro. Drawing inspiration from Escherichia coli Nissle 1917 (EcN), a biomimetic Cur-Fe nanozyme (CF@EM) is subsequently developed by integrating Cur-Fe into the EcN membrane (EM) to improve the in vivo targeting ability and therapeutic effectiveness of the Cur-Fe nanozyme. When orally administered, CF@EM demonstrates a strong ability to colonize the inflamed colon and restore intestinal redox balance and barrier function in DSS-induced colitis models. Importantly, CF@EM influences the gut microbiome towards a beneficial state by enhancing bacterial diversity and shifting the compositional structure toward an anti-inflammatory phenotype. Furthermore, analysis of intestinal microbial metabolites supports the notion that the therapeutic efficacy of CF@EM is closely associated with bile acid metabolism.ConclusionInspired by gut microbes, we have successfully synthesized a biomimetic Cur-Fe nanozyme with the ability to inhibit inflammation and restore intestinal homeostasis. Collectively, without appreciable systemic toxicity, this work provides an unprecedented opportunity for targeted oral nanomedicine in the treatment of ulcerative colitis.

Pseudochrobactrum asaccharolyticum mitigates arsenic induced oxidative stress of maize plant by enhancing water status and antioxidant defense system

BackgroundOxidative stress mediated by reactive oxygen species (ROS) is a common denominator in arsenic toxicity. Arsenic stress in soil affects the water absorption, decrease stomatal conductance, reduction in osmotic, and leaf water potential, which restrict water uptake and osmotic stress in plants. Arsenic-induced osmotic stress triggers the overproduction of ROS, which causes a number of germination, physiological, biochemical, and antioxidant alterations. Antioxidants with potential to reduce ROS levels ameliorate the arsenic-induced lesions. Plant growth promoting rhizobacteria (PGPR) increase the total soluble sugars and proline, which scavenging OH radicals thereby prevent the oxidative damages cause by ROS. The main objective of this study was to evaluate the potential role of Arsenic resistant PGPR in growth of maize by mitigating arsenic stress.MethodologyArsenic tolerant PGPR strain MD3 (Pseudochrobactrum asaccharolyticum) was used to dismiss the ‘As’ induced oxidative stress in maize grown at concentrations of 50 and 100 mg/kg. Previously isolated arsenic tolerant bacterial strain MD3 “Pseudochrobactrum asaccharolyticum was used for this experiment. Further, growth promoting potential of MD3 was done by germination and physio-biochemical analysis of maize seeds. Experimental units were arranged in Completely Randomized Design (CRD). A total of 6 sets of treatments viz., control, arsenic treated (50 & 100 mg/kg), bacterial inoculated (MD3), and arsenic stress plus bacterial inoculated with three replicates were used for Petri plates and pot experiments. After treating with this MD3 strain, seeds of corn were grown in pots filled with or without 50 mg/kg and 100 mg/kg sodium arsenate.ResultsThe plants under arsenic stress (100 mg/kg) decreased the osmotic potential (0.8 MPa) as compared to control indicated the osmotic stress, which caused the reduction in growth, physiological parameters, proline accumulation, alteration in antioxidant enzymes (Superoxide dismutase-SOD, catalase-CAT, peroxidase-POD), increased MDA content, and H2O2 in maize plants. As-tolerant Pseudochrobactrum asaccharolyticum improved the plant growth by reducing the oxidation stress and antioxidant enzymes by proline accumulation. PCA analysis revealed that all six treatments scattered differently across the PC1 and PC2, having 85.51% and 9.72% data variance, respectively. This indicating the efficiency of As-tolerant strains. The heatmap supported the As-tolerant strains were positively correlated with growth parameters and physiological activities of the maize plants.ConclusionThis study concluded that Pseudochrobactrum asaccharolyticum reduced the ‘As’ toxicity in maize plant through the augmentation of the antioxidant defense system. Thus, MD3 (Pseudochrobactrum asaccharolyticum) strain can be considered as bio-fertilizer.

Protein glycosylation inhibitory effects and mechanisms of phloretin and phlorizin

The anti-glycation potential and mechanism of phloretin and phlorizin were investigated in the study. In the methylglyoxal (MGO)-human serum albumin (HSA) glycosylation system, the inhibition against fluorescent advanced glycosylation end products (AGEs) was more than 60% at 960 μM phloretin and phlorizin. They decreased carbonylation and oxidative damage of protein, protected thiol groups and secondary structure of protein and inhibited protein aggregates. Treated with 1.37 mM phloretin or phlorizin, O2−· scavenging was more than 80%, and 1 mM phloretin or phlorizin chelated 60.08% or 28.11% of Fe2+, respectively. Analysis of HPLC and LC-QqQ-MS shown phloretin captured MGO by forming adducts with MGO, with capture rates of 92.67% within 24 h. The capture rate of phlorizin to MGO was 56.40%. The anti-glycosylation mechanisms of them could include the structural protection of HSA, capture of MGO, O2−· and ·OH scavenging and chelation of Fe2+. These findings may provide a theoretical basis for the application of phloretin and phlorizin as novel anti-glycosylation agents.

Superfine grinding combined with enzymatic modification of pea dietary fibre: Structures, physicochemical properties, hypoglycaemic functional properties, and antioxidant activities

N-SDF, S-SDF, E-SDF, and SE-SDF were extracted from natural pea dietary fibre (DF) and modified pea DF by superfine grinding (S), enzymatic modification (E), and superfine grinding combined with enzymatic modification (SE). The structures, physicochemical properties, hypoglycaemic functional properties, and antioxidant activities of the three types of modified SDF were compared with those of natural N-SDF. The results showed that the four SDF types had similar infrared spectra and monosaccharide compositions, whereas their main functional groups, binding degree, and monosaccharide content were different. The molecular weights of S-SDF and SE-SDF decreased compared to that of natural N-SDF, whereas that of E-SDF increased. The microstructure of SE-SDF showed the softest, roughest, and most porous morphology compared with those of the other three SDF types. The hypoglycaemic functional properties (glucose adsorption capacity, glucose dialysis retardation index, and α-amylase inhibition rate) of the three modified SDF types were improved compared with the natural N-SDF. Moreover, SE-SDF had the best effect. In addition, the DPPH· scavenging ability, reducing power, and ·OH scavenging ability of S-SDF and SE-SDF were improved compared with those of natural N-SDF. Remarkably, all four SDF types exhibited excellent ABTS· scavenging ability at a concentration of 0.6 mg/mL. Consequently, SE-SDF holds promise as an outstanding food additive for reducing postprandial blood glucose levels, enhancing antioxidant activities, and mitigating oxidative damage.

Multiple Roles of Anions on the Degradation Efficiency and Mineralization Pathway of Recalcitrant Acetaldehyde by Vacuum Ultraviolet (185 nm) Oxidation.

Vacuum-UV (185 nm, VUV) is widely applied to polish reverse osmosis permeate (ROP), such as the production of electronics-grade ultrapure water. In this study, the VUV oxidation of acetaldehyde, a common carbonyl in ROP, was found to be influenced by anions even at low concentrations. Interestingly, the influencing extent and mechanism varied depending on the anions. Bicarbonate minimally affected the VUV-photon absorption and •OH consumption, but at 5000 μg-C·L-1, it decreased the degradation of acetaldehyde by 58.7% possibly by scavenging organic radicals or other radical chain reactions. Nitrate strongly competed for VUV-photon absorption and •OH scavenging through the formation of nitrite, and at 500 μg-N·L-1, it decreased the removal rate of acetaldehyde degradation by 71.2% and the mineralization rate of dissolved organic carbon by 53.4%. Chloride competed for VUV-photon absorption and also generated reactive chlorine species, which did not affect acetaldehyde degradation but influenced the formation of organic byproducts. The radical chain reactions or activation of anions under VUV irradiation could compensate for the decrease in oxidation performance and need further investigation. In real ROPs, the VUV oxidation of acetaldehyde remained efficient, but mineralization was hindered due to nitrate and chloride anions. This study deepens the understanding of the photochemistry and feasibility of VUV in water with low concentrations of anions.

Effects of Exidia yadongensis polysaccharide as emulsifier on the stability, aroma, and antioxidant activities of fat-free stirred mango buffalo yogurt

Because of the poor stability and rheological properties of fat-free stirred yogurt fortified with fruit pulp, new functional polysaccharides as a natural emulsifier, which can increase viscosity in the aqueous phase, may be needed. This study aimed to evaluate the effects of Exidia yadongensis polysaccharide (EYP) as emulsifier on the stability, aroma, and antioxidant activities of mango buffalo yogurt at 4 °C for 25 days. The yogurt with 15 g/L EYP gave a higher content of 215 g/L total solids, 11.3 g/L exopolysaccharides, 0.10 g/L total polyphenols, 630.5 g/L water-holding capacity, and 11.43 g/kg total free amino acids, and maintained better texture, DPPH scavenging activity of 54.05 % and OH scavenging rates of 67.16 %. Moreover, the EYP exhibited the expected ability to weaken postacidification, syneresis, and growth of microorganism, and greatly promote the textural, rheological properties, suspension stability, microstructure, and aroma profiles of stirred mango-flavored buffalo yogurt (p < 0.05). In addition, the addition of 15 g/L EYP can inhibit protein degradation and improve the stability of secondary structure of the protein complex in mango yogurt during 25 days of storage. Therefore, EYP (15 g/L) could be used as natural positive functional factors and emulsifiers in such fat-free stirred yogurt industry.

Electrochemical Hydrogen Peroxide Generation and Activation Using a Dual-Cathode Flow-Through Treatment System: Enhanced Selectivity for Contaminant Removal by Electrostatic Repulsion.

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.

Dihydroquercetin and biochaga reduce H2O2 induced DNA damage in peripheral blood mononuclear cells of obese women in vitro-a pilot study.

Systemic oxidative stress stemming from increased free radical production and reduced antioxidant capacity are common characteristics of obese individuals. Using hydrogen peroxide (H2O2) to induce DNA damage in vitro, in peripheral blood mononuclear cells (PBMCs) from obese subjects and controls, the DNA protective ability of dihidroqercetin (DHQ) and biochaga (B) alone or in combination, were evaluated. The effects of DHQ and B were estimated under two experimental conditions: pre-treatment, where cells were pre-incubated with the substances prior to H2O2 exposure; and post-treatment when cells were first exposed to H2 H2O2, and further treated with the compounds. DNA damage was evaluated using the comet assay. The results of pre- and post-treatment showed a significant decrease in DNA damage produced by H2O2 in the obese group. This decrease was not significant in control group probably due to a small number of subjects in this pilot study. More prominent attenuation was noted in the pre-treatment with DHQ (250 μg/mL). Analysis of antioxidant properties revealed that DHQ's remarkable reducing power, 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging activity, and potent ∙OH scavenging properties may contribute to strong attenuation of H2O2 induced DNA damage. Also, B showed strong reducing power, DPPH, and ∙OH scavenging ability, while reducing power and DPPH scavenger effects were increased in the presence of DHQ. Conclusively, DHQ and B may reduce H2O2-induced DNA damage in PBMCs from obese subjects when challenged in vitro, and could be valuable tools in future research against oxidative damage-related conditions.

From waste to wonder: exploring the hypoglycemic and anti-oxidant properties of corn processing by-products.

Introduction: The industrial processing of corn (Zeamays L.) generates by-products such as corn silk, straw peels, and straw core, which contribute to adverse environmental impacts. Our study aimed to investigate sustainable approaches for mitigating these effects by evaluating the hypoglycemic potential and mechanisms of ethyl acetate fractions derived from these corn derivatives. Methods: We employed glucose consumption assays, high glucose stress tests, UPLC-QE-Orbitrap-MS analysis, molecular docking, and simulations to assess their components and efficacy. Antioxidant capacities were evaluated using DPPH, FRAP, ABTS, and •OH scavenging assays. Results: Notably, the ethyl acetate fraction extracted from straw peels (SPE) exhibited a high concentration of flavonoids and phenolic compounds along with pronounced hypoglycemic activity and antioxidant capacity. SPE significantly enhanced glucose consumption in insulin-resistant HepG2 cells while protecting HUVECs against damage caused by high glucose levels. Molecular docking analyses confirmed the interaction between active compounds and α-glucosidase as well as α-amylase, while molecular dynamic simulations indicated stability at their binding sites. Discussion: In conclusion, the hypoglycemic and antioxidative properties observed in corn by-products such as straw peels, corn silk, and straw core can be attributed to the inhibition of α-glucosidase and α-amylase activities, coupled with their rich phenolic and flavonoid content. These findings highlight the potential of these by-products for applications in healthcare management and their sustainable utilization, demonstrating significant value in the use of agricultural residues.

·OH Scavenger Optimized Grounding Electrode Atomization Corona Discharge Technology for Treatment of Coal Mine Acidic Wastewater

Coal mine acid drainage is a type of industrial wastewater generated in the process of coal production and utilization that has a low pH and contains a small amount of organic matter and SO42−, which is harmful to the environment. The ·OH scavenger was used to optimize the grounded electrode atomized corona discharge (GEACD) technology for the treatment of coal mine acidic wastewater. The effects of various factors on the discharge effect were investigated, and the optimal operating scheme for the subsequent test was determined as 35 mm distance between barrel electrodes, 0.6 mm diameter of wire electrodes, and a flow rate of 45 mL/min. The effects of discharge voltage, discharge time, and ·OH scavenger on COD removal rate and pH in coal mine acid drainage were also investigated. The results showed that at the optimum discharge voltage of 12 kV, discharge time of 66 min, and SO42− to ethanol concentration ratio of 1, the COD value decreased from 152.84 mg/L to 43.27 mg/L, and the pH value increased from 5.6 to 6.1.

Insight into the surface discharge cold plasma efficient inactivation of Pseudomonas fluorescens in water based on exogenous reactive oxygen and nitrogen species: Synergistic mechanism and energy benefits

As well known, surface discharge cold plasma has efficient inactivation ability and a variety of RONS are main active particles for inactivation, but their synergistic mechanism is still not clear. Therefore, surface discharge cold plasma system was applied to treat Pseudomonas fluorescens to study bacterial inactivation mechanism and energy benefit. Results showed that energy efficiency was directly proportional to applied voltage and inversely proportional to initial concentration. Cold plasma treatment for 20 min was inactivated by approximately > 4-log10Pseudomonas fluorescens and application of •OH and 1O2 scavengers significantly improved survival rate. In addition, •OH and 1O2 destroyed cell membrane structure and membrane permeability, which promoted diffusion of RONS into cells and affecting energy metabolism and antioxidant capacity, leading to bacterial inactivation. Furthermore, accumulation of intracellular NO and ONOOH was related to infiltration of exogenous RNS, while accumulation of •OH, H2O2, 1O2, O2- was the result of joint action of endogenous and exogenous ROS. Transcriptome analysis revealed that different RONS of cold plasma were responsible for Pseudomonas fluorescens inactivation and related to activation of intracellular antioxidant defense system and regulation of genes expression related to amino acid metabolism and energy metabolism, which promoting cellular process, catalytic activity and other biochemical pathways.

Selenium-Chelating Peptide Derived from Wheat Gluten: In Vitro Functional Properties.

The efficacy of selenium-chelating polypeptides derived from wheat protein hydrolysate (WPH-Se) includes enhancing antioxidant capacity, increasing bioavailability, promoting nutrient absorption, and improving overall health. This study aimed to enhance the bioavailability and functional benefits of exogenous selenium by chelating with wheat gluten protein peptides, thereby creating bioactive peptides with potentially higher antioxidant capabilities. In this study, WPH-Se was prepared with wheat peptide and selenium at a mass ratio of 2:1, under a reaction system at pH 8.0 and 80 °C. The in vitro antioxidant activity of WPH-Se was evaluated by determining the DPPH, OH, and ABTS radical scavenging rate and reducing capacity under different conditions, and the composition of free amino acids and bioavailability were also investigated at various digestion stages. The results showed that WPH-Se possessed significant antioxidant activities under different conditions, and DPPH, OH, and ABTS radical scavenging rates and reducing capacity remained high at different temperatures and pH values. During gastrointestinal digestion in vitro, both the individual digestate and the final digestate maintained high DPPH, OH, and ABTS radical scavenging rates and reducing capacity, indicating that WPH-Se was able to withstand gastrointestinal digestion and exert antioxidant effects. Post-digestion, there was a marked elevation in tryptophan, cysteine, and essential amino acids, along with the maintenance of high selenium content in the gastrointestinal tract. These findings indicate that WPH-Se, with its enhanced selenium and amino acid profile, serves as a promising ingredient for dietary selenium and antioxidant supplementation, potentially enhancing the nutritional value and functional benefits of wheat gluten peptides.

TiO2 nanoparticle photoactivation and oxidation reactions in freshwater and marine systems: The role of radical scavengers

Titanium dioxide nanoparticles (TiO2-NP) present in wastewater effluent are discharged into freshwater and saltwater (i.e., marine) systems. TiO2-NP can be solar-driven photoactivated by ultraviolet (UV)-light producing reactive oxygen species including hydroxyl radicals (·OH). ·OH are non-selective and react with a broad range of species in water. In other studies, photoactivation of TiO2-NP has been correlated with oxidative stress and ecotoxicological impacts on plant and animal biota. This study examined the photoactivation of TiO2-NP in freshwater and saltwater systems, and contrasted the oxidation potential in both systems using methylene blue (MB) as a reaction probe. Maximum MB loss (51.9%, n = 4; 95% confidence interval 49.4–54.5) was measured in salt-free, deionized water where ·OH scavenging was negligible; minimum MB loss (1%) was measured in saltwater due to significant ·OH scavenging, indicating the inverse correlation between MB loss and radical scavenging. A kinetic analysis of scavenging by seawater constituents indicated Cl− had the greatest impact due to high concentration and high reaction rate constant. Significant loss of MB occurred in the presence of Br− relative to other less aggressive scavengers present in seawater (i.e., HCO3−, HSO4−). This result is consistent with the formation of Bromate, a strong oxidant that subsequently reacts with MB. In freshwater samples collected from different water bodies in Oklahoma (n = 12), the average MB loss was 13.4%. Greater MB loss in freshwater systems relative to marine systems was due to lower ·OH scavenging by various water quality parameters. Overall, TiO2-NP photoactivation in freshwater systems has the potential to cause greater oxidative stress and ecotoxicological impacts than in marine systems where ·OH scavenging is a dominant reaction.

Trivalent Copper Ion-Mediated Dual Oxidation in the Copper-Catalyzed Fenton-Like System in the Presence of Histidine.

The Cu(II)/H2O2 system is recognized for its potential to degrade recalcitrant organic contaminants and inactivate microorganisms in wastewater. We investigated its unique dual oxidation strategy involving the selective oxidation of copper-complexing ligands and enhanced oxidation of nonchelated organic compounds. L-Histidine (His) and benzoic acid (BA) served as model compounds for basic biomolecular ligands and recalcitrant organic contaminants, respectively. In the presence of both His and BA, the Cu(II)/H2O2 system rapidly degraded His complexed with copper ions within 30 s; however, BA degraded gradually with a 2.3-fold efficiency compared with that in the absence of His. The primary oxidant responsible was the trivalent copper ion [Cu(III)], not hydroxyl radical (•OH), as evidenced by •OH scavenging, hydroxylated BA isomer comparison with UV/H2O2 (a •OH generating system), electron paramagnetic resonance, and colorimetric Cu(III) detection via periodate complexation. Cu(III) selectively oxidized His owing to its strong chelation with copper ions, even in the presence of excess tert-butyl alcohol. This selectivity extended to other copper-complexing ligands, including L-asparagine and L-aspartic acid. The presence of His facilitated H2O2-mediated Cu(II) reduction and increased Cu(III) production, thereby enhancing the degradation of BA and pharmaceuticals. Thus, the Cu(II)/H2O2 system is a promising option for dual-target oxidation in diverse applications.

Rosmarinic acid, a natural polyphenol, has a potential pro-oxidant risk via NADH-mediated oxidative DNA damage

BackgroundRosmarinic acid (RA) has a wide range of beneficial effects on human health. On the other hand, RA has been reported to induce metal-mediated reactive oxygen species (ROS) generation and DNA damage. However, its mechanism remains unknown. In this study, to clarify the underlying mechanism, we analyzed metal-mediated DNA damage in isolated DNA treated with RA and its analog isorinic acid.ResultsRA plus Cu(II), but not Fe(III), significantly increased 8-oxo-7,8-dihydro-2’-deoxyguanosine (8-oxodG) formation, an indicator of oxidative DNA damage, in calf thymus DNA. Furthermore, a comparison of the 8-oxodG formation induced by RA and its analog isorinic acid suggested that the catechol groups in RA could be associated with their abilities to form 8-oxodG. Interestingly, the 8-oxodG formation induced by RA and isorinic acid plus Cu(II) was markedly enhanced by the addition of NADH, an endogenous reductant. To elucidate the mechanism of RA plus Cu(II)-induced oxidative DNA damage, we examined DNA damage in 32P-labeled DNA treated with RA in the presence of Cu(II). RA plus Cu(II) caused DNA cleavage, which was enhanced by piperidine treatment, suggesting that RA causes not only DNA strand breakage but also base modification. RA plus Cu(II)-induced DNA damage was inhibited by catalase (H2O2 scavenger), bathocuproine (Cu(I) chelator), and methional (scavenger of a variety of ROS other than •OH) but not by typical •OH scavengers and SOD, indicating the involvement of H2O2, Cu(I), and ROS other than •OH. DNA cleavage site analysis showing RA-induced site-specific DNA damage (frequently at thymine and some cytosine residues) supports the involvement of ROS other than •OH, because •OH causes DNA cleavage without site specificity. Based on these results, Cu(I) and H2O2 generation with concomitant RA autoxidation could lead to the production of Cu(I)-hydroperoxide, which induces oxidative DNA damage. o-Quinone and o-semiquinone radicals are likely to be again reduced to RA by NADH, which dramatically increases oxidative DNA damage, particularly at low concentrations of RA.ConclusionsIn this study, physiologically relevant concentrations of RA effectively induced oxidative DNA damage in isolated DNA through redox cycle reactions with copper and NADH.

Structure Elucidation of a Novel Polysaccharide Isolated from Euonymus fortunei and Establishing Its Antioxidant and Anticancer Properties.

Euonymusfortunei polysaccharides (EFPs) have not been extensively investigated yet in terms of their extraction and biological activity. The orthogonal experimental design was employed in this study to evaluate the optimum yield of EFPs. A maximum yield of 2.63 ± 0.23% was attained using material-liquid ratios of 60 mL/g, extraction temperature of 80°C, ultrasonic power of 144 W, and extraction time of 75 mins. The polysaccharide content reached 53.47 ± 0.31% when deproteinized thrice. An analysis of monosaccharide composition revealed that these polysaccharides consist of Gal, Glc, Man, Fuc, and Rha with a molar ratio of 7.14 ∶ 23.99 ∶ 6.29 ∶ 6.55 ∶ 1.00, respectively, in EFPs. Subsequently, the in vitro scavenging capacities of 2,2-diphenylpicrylhydrazyl (DPPH) and ·OH and superoxide anion radicals, along with the reducing power of EFPs, were studied. Results revealed that EFPs have higher antioxidant activity, particularly ·OH scavenging, as well as reducing power, as compared to Astragalus polysaccharides (ASPs) and Lycium barbarum polysaccharides (LBPs). The Cell Counting Kit-8 (CCK-8) method was used to evaluate the effects of different concentrations of polysaccharides on SKOV3 cell proliferation, and the results revealed their inhibition at concentrations in the range of 200-800 μg/mL. In addition, findings from flow cytometry further confirmed that EFPs blocked the cell cycle at G0/G1 and S phases and induced SKOV3 cell apoptosis. In a word, EFPs could be exploited and used further based on the experimental results from this study.

Interaction of rice root Fe plaque with radial oxygen loss enhances paddy-soil N2O emission by increasing •OH production and subsequently inhibiting N2O reduction

Amorphous iron (Fe) oxides are commonly deposited on rice roots, forming a distinctive Fe plaque, which has been observed as a notable hotspot for increased nitrous oxide (N2O) emission from paddy fields. However, the precise mechanisms underlying this phenomenon have remained uncertain. We hypothesized that the interaction between Fe plaque and rice root radial oxygen losses (ROL) leads to the generation of hydroxyl radical (•OH), thereby inhibiting N2O reduction and increasing N2O emission. To test this hypothesis, we transplanted rice seedlings with induced Fe plaque coating alongside those without Fe plaque coating into the same paddy soil. The results showed that paddy soil with Fe plaque-coated rice seedlings exhibited significantly higher concentrations of •OH and increased N2O emission rates, but a reduced abundance of the microbial N2O reduction gene (nosZ), compared to paddy soil with Fe plaque-free rice seedlings. These observed differences in N2O emission disappeared when we introduced an •OH scavenger into the paddy soil or shaded the rice leaves to reduce ROL. Furthermore, the supplementation of Fe (II) into the paddy soil with Fe plaque-free rice seedlings markedly increased •OH concentrations and N2O emissions. Our results demonstrate that Fe plaque, in conjunction with rice root ROL, facilitates •OH generation through the Fenton reaction. This •OH production effectively inhibits microbial N2O reduction, ultimately leading to increased N2O emissions from paddy soils. Our study uncovers a new mechanism whereby Fe plaque enhances N2O emissions from paddy soil. Minimizing Fenton reactions on Fe plaque may offer a promising strategy for reducing N2O emissions from paddy fields.