Oxidative Conditions Research Articles

The mitochondria‒paraspeckle axis regulates the survival of transplanted stem cells under oxidative stress conditions.

Rationale: Stem cell-based therapies have emerged as promising tools for tissue engineering and regenerative medicine, but their therapeutic efficacy is largely limited by the oxidative stress-induced loss of transplanted cells at injured tissue sites. To address this issue, we aimed to explore the underlying mechanism and protective strategy of ROS-induced MSC loss. Methods: Changes in TFAM (mitochondrial transcription factor A) signaling, mitochondrial function, DNA damage, apoptosis and senescence in MSCs under oxidative stress conditions were assessed using real-time PCR, western blotting and RNA sequencing, etc. The impact of TFAM or lncRNA nuclear paraspeckle assembly transcript 1 (NEAT1) knockdown or overexpression on mitochondrial function, DNA damage repair, apoptosis and senescence in MSCs was also analyzed. The effect of mitochondrion-targeted antioxidant (Mito-TEMPO) on the survival of transplanted MSCs was evaluated in a mouse model of renal ischemia/reperfusion (I/R) injury. Results: Mitochondrial ROS (mtROS) bursts caused defects in TFAM signaling and overall mitochondrial function, which further impaired NEAT1 expression and its mediated paraspeckle formation and DNA repair pathways in MSCs, thereby jointly promoting MSC senescence and death under oxidative stress. In contrast, targeted inhibition of the mtROS bursts is a sufficient strategy for attenuating early transplanted MSC loss at injured tissue sites, and coadministration of Mito-TEMPO improved the local retention of transplanted MSCs and reduced oxidative injury in ischemic kidneys. Conclusions: This study identified the critical role of the mitochondria‒paraspeckle axis in regulating cell survival and may provide insights into developing advanced stem cell therapies for tissue engineering and regenerative medicine.

TWO-STAGE PALM KERNEL SHELL WASHING WITH WATER AND ACETIC ACID AS PREPARATION OF CO-FIRING SYSTEM WITH COAL

Palm kernel shells (PKS) were washed with water and glacial acetic acid (CH3COOH) gradually to prepare them for co-firing with coal. They were then torrefied at 450ºC for one hour. Washing was done to reduce the concentration of ash and alkaline oxides, which would reduce the chance of slagging and fouling. The research was conducted considering that information about washing the PKS with acetic acid and then having them torrefied is very limited and unclear. The results showed that washed and torrefied PKS had better characteristics than those of raw PKS or PKS washed with water. PKS that is washed with acid, torrefied and then blended with coal has low slagging and medium fouling tendencies. However, based on ash fusion temperature, the inclination towards slagging and fouling is high under reducing conditions and medium under oxidation conditions.

Recent advances in oxidative dearomatization involving C-H bonds for constructing value-added oxindoles.

Exploring three-dimensional chemical space is an important research objective of organic synthetic chemistry. Oxidative dearomatization (ODA) is one of the most important and powerful tools for realizing this goal, because it changes and removes aromatic structures from aromatic compounds to increase levels of saturation and stereoisomerism by direct addition reactions between functional groups with aromatic cores under oxidative conditions. As a hot topic in indole chemistry, the synthetic value of the oxidative dearomatization of indoles has been well recognized and has witnessed rapid development recently, since it could provide convenient and unprecedented access to fabricate high-value-added three-dimensional oxindole skeletons, such as C-quaternary indolones, polycycloindolones and spiroindolones, and be widely applied to the total synthesis of these oxindole alkaloids. Therefore, this article provides a review of recent developments in oxidative dearomatization involving the C-H bonds of indoles. In this article, the features and mechanisms of different types of ODA reactions of indoles are summarized and represented, and asymmetric synthesis methods and their applications are illustrated with examples, and future development trends in this field are predicted at the end.

Functional implications of unusual NOS and SONOS covalent linkages found in proteins.

The tertiary and quaternary structures of many proteins are stabilized by strong covalent forces, of which disulfide bonds are the most well known. A new type of intramolecular and intermolecular covalent bond has been recently reported, consisting of the Lys and Cys side-chains linked by an oxygen atom (NOS). These post-translational modifications are widely distributed amongst proteins, and are formed under oxidative conditions. Similar linkages are observed during antibiotic biosynthesis, where hydroxylamine intermediates are tethered to the sulfur of enzyme active site Cys residues. These linkages open the way to understanding protein structure and function, give new insights into enzyme catalysis and natural product biosynthesis, and offer new strategies for drug design.

Gold oxide formation on Au(111) under CO oxidation conditions at room temperature.

Although gold-based catalysts are promising candidates for selective low-temperature CO oxidation, the reaction mechanism is not fully understood. On a Au(111) model catalyst, we observe the formation of gold oxide islands under exposure to atmospheric pressures of oxygen or CO oxidation reaction conditions in an in situ scanning tunneling microscope. The gold oxide formation is interpreted in line with the water-enabled dissociation of O2 on the step edges of Au(111). Contaminants on the gold surface can strongly promote the gold oxide formation even on the terraces. On the other hand, TiO2 nanoparticles on the Au(111) do not show any influence on the formation of the gold oxide and are thus not providing a significant amount of atomic oxygen to the gold at room temperature. Overall, the presence of gold oxide is likely under industrial conditions.

Thermocatalytic epoxidation by cobalt sulfide inspired by the material's electrocatalytic activity for oxygen evolution reaction.

New discoveries in catalysis by earth-abundant materials can be guided by leveraging knowledge across two sub-disciplines of heterogeneous catalysis: electrocatalysis and thermocatalysis. Cobalt sulfide has been reported to be a highly active electrocatalyst for the oxygen evolution reaction (OER). Under these oxidative conditions, cobalt sulfide forms oxidized surfaces that outperform directly prepared cobalt oxide in OER catalysis. We postulated that the catalytic activity of oxidized cobalt sulfide for OER could reflect a more general ability to catalyze O-transfer reactions. Herein, we show that cobalt sulfide (CoS x ) indeed catalyzes the epoxidation of cyclooctene, a thermal O-transfer reaction. Similarly to OER, the surface-oxidized CoS x formed under reaction conditions outperformed the directly prepared cobalt oxide, hydroxide, and oxyhydroxide for epoxidation catalysis. Another notable phenomenological parallel to OER was revealed by the electron paramagnetic resonance (EPR) analysis of all spent Co-based catalysts that showed significant structural changes and the formation of paramagnetic Co(ii) and Co(iv) species. Mechanistic investigations suggest that a higher density of Co(ii) and/or an easier formation of high-valent Co species in the case of surface-oxidized cobalt sulfide is responsible for its high activity as an epoxidation catalyst. Our results provide important insight into the surface chemistry of Co-based catalysts and show the potential of oxidized CoS x as an earth-abundant catalyst for O-transfer reactivity beyond OER. This work highlights the utility of bridging electrocatalysis and thermocatalysis for the development of more sustainable chemical processes.

Iridium(III)-catalyzed β-trifluoromethyl enone carbonyl-directed regioselective ortho-C(sp2)-H olefination.

Due to the lower LUMO energy level at the β-position of α,β-unsaturated-β-trifluoromethyl enone than that of its non-fluorinated counterpart, there is a challenge to activate the sp2 C-H bond of aromatic rings. Herein, we have reported iridium(III)-catalyzed β-trifluoromethyl enone carbonyl-directed regioselective aromatic C(sp2)-H olefination with acrylates under oxidative conditions. Furthermore, coupling with natural product-derived acrylates, scale-up and product diversification have also been performed.

Morphology-electronic effects in ultra-model nanocatalysts under the CO oxidation reaction: the case of ZnO ultrathin films grown on Pt(111).

The study of the surface morphology and interface of metal-oxides is crucial for understanding the behavior of these model systems as nanocatalysts. Besides, understanding the interplay between morphology, stability, and reactivity is crucial for designing efficient catalysts. Here, we investigated the stability and dewetting of ZnO ultrathin films on Pt(111) under CO oxidation conditions. For films <1 monolayer (ML), CO-induced dewetting occurs at the metal-oxide interface or defects. The morphology, dependent on thickness, influences reactivity. (6 × 6) structures show greater CO binding and structural changes compared to (4 × 4) structures, which exhibit resilience due to Zn-OH formation. ZnO electronic properties, as revealed by Auger spectroscopy and scanning tunneling spectroscopy (STS) investigations, vary with thickness. Low-thickness films [<2 monolayers (ML)] exhibit metallic-like behavior, possibly due to Zn-Pt interaction, while thicker films show n-type semiconductor behavior with a bandgap opening (EBG = 0.9 eV at 2 ML). DFT calculations of the local density of states (LDOS) as a function of ZnO thickness confirm the thickness-dependent electronic structure, with 0.3 ML films having a higher LDOS near the Fermi level than 1 ML films. These findings highlight the critical role of ZnO morphology in determining its stability and reactivity which opens up avenues for designing efficient and more stable ZnO-based nanocatalysts for a wide range of chemical reactions, including CO oxidation and CO2 hydrogenation.

Isolation, identification and structural characterization of forced degradation products of mobocertinib using LC-MS/MS and NMR

The main objective of this study is to develop and validate an LC-MS/MS stability-indicating method for the isolation, identification, and characterization of forced degradation products of mobocertinib under various stress conditions, utilizing LC-MS/MS and NMR techniques. Four degradation products (DP1, DP2, DP3 and DP4) were isolated. Degradation under acidic and oxidative conditions provides DP1 and DP4, respectively. Both DP2 and DP3 were obtained under basic conditions. Chromatographic development and separation were achieved using an ODS C18 column (Chemsil) with a constant flow rate of 1.0 ml/min. The mobile phase consisted of 40 % water containing 0.1 % formic acid in methanol, and detection was performed at a wavelength of 225 nm. The application of LC-MS/MS technology was utilized to separate the above degradation products. The LC-MS/MS method has validated which includes specificity, linearity, LOD and LOQ, precision, accuracy and robustness. The chemical structure of the degradation products were characterized by 1H NMR and mass spectroscopy. The above listed degradation impurities are novel and not listed in the literature. In conclusion, this study provides vital information about mobocertinib’s chemical stability and helpful in further drug development process.

A new {P4Mo6}-based complex as a highly efficient heterogeneous catalyst for the oxidation of alkylbenzenes under mild conditions

A new {P4Mo6}-based manganese complex was prepared under solvothermal conditions for efficient catalytic oxidation of diphenylmethane.

Isolation and characterization of novel degradation products in fenoverine by LC-QTOF-MS/MS, LC-MSn and 2D-NMR

Fenoverine was subjected to stress studies under various conditions to evaluate its degradation profile. The drug is highly susceptible to oxidative and alkaline stress conditions at room temperature, which resulted in five oxidative degradants and two alkaline degradants.

Development of gummy bear supplements and in vitro exploration of antioxidant and antiproliferative potential of Nuciferine

BackgroundNuciferine's extensive therapeutic potential, including its robust antioxidant properties, is explored in response to the growing consumer preference for value-added organic foods. ObjectiveThis study focuses on the formulation of gummy bear supplements fortified with nuciferine from Nelumbonucifera. The research highlights nuciferine's ability to combat oxidative stress induced by reactive oxygen species (ROS) and examines its application in maintaining basal ROS levels during oxidative stress conditions in skin melanoma cells. MethodsCharacterization of extracted nuciferine through FTIR and UV–vis spectroscopy ensures product quality, while sensory evaluation compares honey and sugar as natural sweeteners for optimal flavor and consumer preference. SK-Mel-28 cellular ROS levels were measured using 2′,7’ –dichlorofluorescin diacetate dye before and after nuciferine treatment. SK-Mel-28 cell viability and dose response of nuciferine treatment was assessed using MTT assay. ResultsNuciferine shows potent inhibition of SK-Mel-28 cell proliferation with an IC50 of 39.31 ± 5.280 μg/ml and showed no cytotoxicity in normal L6 skeletal muscle cells. This study compares the sensory properties of honey and sugar based gummy bear formulations. ConclusionThis project aims to create a high-quality, health-promoting dietary supplement that aligns with the evolving trends in organic nutrition and antioxidant supplementation.

Protective Effect of Overexpression of Uqcrc1 in H2O2-Induced Myocardial Injury

This study investigated the role of Uqcrc1 in oxidative stress and apoptosis induced by hydrogen peroxide (H2O2) in cardiomyocytes. H9c2 cells were divided into four groups: control, H2O2-treated, Lv-NC+H2O2 (negative control lentivirusinfected with H2O2), and Lv-Uqcrc1+H2O2 (Uqcrc1 overexpressed lentivirus-infected with H2O2 for 12 hours). Uqcrc1 expression was quantified using qRT-PCR and Western blotting. Cell proliferation was assessed with CCK-8, and various oxidative stress markers (LDH, MDA, SOD, CAT, GSH-Px) were measured. Apoptosis was evaluated using Tunel assays, intracellular ROS levels, and Cleaved Caspase3 and Caspase9 expression. Additionally, the impact on the Wnt/β-catenin pathway was examined. In the Lv-Uqcrc1 group, Uqcrc1 expression was notably higher. H2O2 treatment reduced cell proliferation and increased LDH leakage, MDA, ROS levels, and apoptosis. Cleaved Caspase3 and Caspase9 expression increased, indicating apoptosis. Lv-Uqcrc1+H2O2 group exhibited improved cell proliferation, decreased LDH leakage, increased CAT, SOD, GSH-Px activities, reduced MDA and ROS levels, and reduced apoptosis with lower Cleaved Caspase3 and Caspase9 expression. Uqcrc1 overexpression also inhibited Wnt/β-catenin pathway overactivation. In oxidative stress conditions, Uqcrc1 protected against myocardial cell injury, reducing apoptosis and oxidative damage. This study highlights Uqcrc1’s significance in cardiovascular diseases.

STABILITY INDICATING UPLC METHOD FOR ESTIMATION OF BENAZEPRIL AND HYDROCHLOROTHIAZIDE IN BULK AND COMBINED DOSAGE FORM

Objective: The main objective was to develop stability indicating UPLC technique for simultaneous estimation of Benazepril and Hydrochlorothiazide in bulk and formulation. Methods: 0.1% Triethylamine phosphate: Methanol (25:75v/v) was used as the mobile phase. Benazepril linearity was found to be 4-20 µg/ml and Hydrochlorothiazide linearity was found to be 5-25 g/ml. The detection wavelength was 236 nm, and the retention period of Benazepril was 3.4 min and Hydrochlorothiazide was 5.4 min with a flow rate of 1.0 ml/min. According to the ICH guidlines, the proposed method was validated and stress studies revealed that the drugs are prone to alkali and peroxide stress conditions. Results: The calibration curve was plotted, and the regression equations for Benazepril were y = 2,01,491.67x+60,532.30 with a correlation coefficient (r2) of 0.9997 and Hydrochlorothiazide were y = 64,635.86x-74,607.10 with a correlation coefficient (r2) of 0.9994. According to the accuracy research, the percent recovery of Benazepril is 99.09-100.69 % and that of Hydrochlorothiazide is 98.27-101.88%, both of which are within the ICH recommendations. Benazepril has a limit of detection of 0.08 g/ml-0.24 g/ml and Hydrochlorothiazide has a limit of quantitation of 0.03 g/ml-0.10 g/ml. The procedure was found to be straightforward, linear, rapid, exact, repeatable, and robust. It was determined that the % RSD was within ICH norms. Stress degradation tests showed the drug's vulnerability to oxidative, thermal, photolytic, acid, basic, and neutral hydrolysis stress conditions. Under the circumstances of alkali and peroxide stress, it was discovered that the drug degraded most quickly. Conclusion: The developed chromatographic technique under consideration was suitable for the accurate, precise, and quick simultaneous measurement of hydrochlorothiazide and benazepril in both their bulk and medicinal dose forms.

Fundamental studies of ruthenium species supported on boron nitride nanotubes: metal loading and pretreatment effects on CO oxidation

RuOx/BNNT catalysts were prepared with varying metal loadings and under oxidation and reduction conditions. RuOx/BNNT showed superior catalytic activity than Ru/BNNT. The catalyst will be favorable to the ER mechanism over the LH mechanism.

Antioxidant activity of chia flour as a food supplement in a cellular model: Repercussions of processing and in vitro digestion

Food processing and digestion can alter bioactive compound composition of food, affecting their potential biological activity. In this study, we evaluated the direct and protective antioxidant effects of polyphenols extracted from defatted chia flour (DCF) (salviaflaside, rosmarinic and fertaric acid as major compounds), sweet cookies supplemented with DCF (CFC) (same major compounds), and their digested fractions (rosmarinic acid, salviaflaside, fertaric and salvianolic E/B/L acid as major compounds) in HepG2 cells in basal and in oxidative stress conditions. DCF showed protective antioxidant effects by decreasing reactive oxygen species (ROS) and protein oxidation products (POP) while increasing reduced glutathione (GSH). Additionally, CFC revealed similar protective effects and even showed enhanced modulation of the antioxidant system due to the activation of antioxidant enzymes. However, the digested fractions only decreased ROS, indicating continued antioxidant effects. This study underscores the importance of evaluating manufacturing and digestion effects to confirm a food's antioxidant properties.

Electrochemical oxidative decarboxylative of α-oxocarboxylic acids towards the synthesis of quinazolines and quinazolinones.

A mild and environmentally electrochemical method for the synthesis of quinazolines and quinazolinones has been developed through anodic oxidation decarboxylative of α-oxocarboxylic acids. The present reaction was efficiently conducted by using simple and cheap NH4I as the N-source and electrolyte in an undivided cell. The desired products, quinazolines and quinazolinones, were isolated in high yield under chemical oxidant free conditions.

Isomangiferin promotes the migration and osteogenic differentiation of rat bone marrow mesenchymal stem cells.

Delayed or failed bone healing is a significant clinical challenge worldwide. Bone marrow mesenchymal stem cells (BMSCs) offer a promising approach for improving fracture healing. Isomangiferin, a xanthone C-glucoside, is known for its pharmacological activities, but its role in fracture healing remains unclear. In this study, we investigated the effects of isomangiferin on BMSCs under oxidative stress conditions induced by hydrogen peroxide (H2O2). Our results showed that isomangiferin promotes osteogenic differentiation and migration of H2O2-treated BMSCs, reduces apoptosis and reactive oxygen species production, and activates the AMP-activated protein kinase/acetyl-CoA carboxylase (AMPK/ACC) pathway. These findings suggest that isomangiferin may be a potential therapeutic agent for enhancing bone healing by modulating BMSC function.

Accurate identification of 8-oxoguanine in RNA with single-nucleotide resolution using ligase-dependent qPCR.

8-oxoguanine (o8G), a prevalent oxidative modification in RNA induced by reactive oxygen species (ROS), plays a pivotal role in regulating RNA functions. Accurate detection and quantification of o8G modifications is critical to understanding their biological significance and potential as disease biomarkers, but effective detection methods remain limited. Here, we have developed a highly specific T3 DNA ligase-dependent qPCR assay that exploits the enzyme's ability to discriminate o8G from guanine (G) with single-nucleotide resolution. This method can detect o8G in RNA at levels as low as 500 fM, with an up to 18-fold higher selectivity for discriminating o8G from G. By simulating oxidative stress conditions in SH-SY5Y and HS683 cell lines treated with rotenone, we successfully identified site-specific o8G modifications in key miRNAs associated with neuroprotective responses, including miR-124, let-7a and miR-29a. The developed assay holds significant promise for the practical identification of o8G, facilitating its potential for detailed studies of o8G dynamics in various biological contexts and diseases.

The RNA chaperone Hfq has a multifaceted role in Edwardsiella ictaluri.

Edwardsiella ictaluri is a Gram-negative, facultative intracellular bacterium that causes enteric septicemia in catfish (ESC). The RNA chaperone Hfq (host factor for phage Qβ replication) facilitates gene regulation via small RNAs (sRNAs) in various pathogenic bacteria. Despite its significance in other bacterial species, the role of hfq in E. ictaluri remains unexplored. This study aimed to elucidate the role of hfq in E.ictaluri by creating an hfq mutant (EiΔhfq) through in-frame gene deletion and characterization. Our findings revealed that the Hfq protein is highly conserved within the genus Edwardsiella. The deletion of hfq resulted in a significantly reduced growth rate during the late exponential phase. Additionally, EiΔhfq displayed a diminished capacity for biofilm formation and exhibited increased motility. Under acidic and oxidative stress conditions, EiΔhfq demonstrated impaired growth, and we observed elevated hfq expression when subjected to in vitro and in vivo stress conditions. EiΔhfq exhibited reduced survival within catfish peritoneal macrophages, although it had no discernible effect on the adherence and invasion of epithelial cells. The infection model revealed that hfq is needed for bacterial persistence in catfish, and its absence caused significant virulence attenuation in catfish. Finally, the EiΔhfq vaccination completely protected catfish against subsequent EiWT infection. In summary, these results underscore the pivotal role of hfq in E. ictaluri, affecting its growth, motility, biofilm formation, stress response, and virulence in macrophages and within catfish host.