Free Radical Research最新文献

Atmospheric pressure low-temperature plasma treatment has been shown to enhance seed germination in various plant species. However, whether plasma treatment modulates seed dormancy status or affects the seed germination process remains unclear. Additionally, most studies have primarily focused on the positive effects of plasma on germination and growth, without addressing dose-dependent responses or underlying molecular mechanisms. To elucidate the effects of plasma treatment on seed germination at a molecular level, we analyzed the germination phenotype of fully ripened Arabidopsis thaliana seeds under germination-inhibitory conditions following plasma treatment. We observed that plasma treatment enhanced germination potential up to a critical threshold, beyond which prolonged treatment diminished the enhanced effect. Chemical staining assays identified that plasma treatment induced the production of reactive oxygen species (ROS) and reactive nitrogen species (RNS) at different time points. Machine-learning aided modeling revealed that ROS, rather than RNS, plays a key role in plasma-mediated germination induction. Furthermore, transcriptome analyses suggested candidate genes likely modulated by plasma treatment during seed germination, including glutathione and L-phenylalanine metabolism, abscisic acid signaling, and the tricarboxylic acid cycle. Our study provides the first molecular-level insights into how atmospheric pressure low-temperature plasma modulates seed germination.

Acute poisoning remains a significant cause of admission to the emergency intensive-care unit (EICU). Despite a reduced mortality rate, attention is increasingly focusing on the impact of post-intensive-care syndrome (PICS) on readmission. Due to the significant role of oxidative stress (OS) in the pathological mechanisms of poisoning, 8-oxo-7,8-dihydroguanosine (8-oxoGuo) and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo) may hold great potential as biomarkers for OS biomarkers to evaluate the severity and prognosis of poisoning. Therefore, we investigated the longitudinal changes of urinary 8-oxoGuo levels during hospitalization in poisoned patients, their association with organ failure, and their predictive value for 30-day readmission risk. In total, 43 poisoning patients were enrolled from the EICU of the First Affiliated Hospital of Wenzhou Medical University between July 2021 and November 2022. The 30-day readmission rate was 18.6%. Group-based trajectory modeling (GBTM) was used to explore the potential trajectories of urinary OS markers and organ failure scores during hospitalization. Spearman's correlation analysis revealed a significant association between a high trajectory of 8-oxoGuo/creatinine (Cr) and the increased severity of overall organ failure, as well as respiratory and coagulation dysfunctions. Binary logistic regression analysis indicated that a high 8-oxoGuo/Cr trajectory, high respiratory failure score trajectory, and 8-oxoGuo/Cr values at three key points in disease progression (including admission, transfer from EICU, and discharge), along with 8-oxodGuo/Cr levels at admission, were all risk factors for 30-day readmission. The 8-oxoGuo/Cr value at discharge exhibited the best predictive performance. The urinary 8-oxoGuo/Cr ratio may serve as a potential biomarker for prognostic evaluations in patients with poisoning.

Macrophages and neutrophils are the main immune cells of the acute stage of inflammation. Upon their activation, membrane-bound NADPH oxidase produces superoxide anion radical, which is converted to H₂O₂ by superoxide dismutase (SOD). In this study, we compared the production of hydrogen peroxide by two phenotypes of pro-inflammatory human M1 macrophages and neutrophils activated with phorbol-12-myristate 13-acetate. Macrophages were obtained from blood monocytes (monocyte-derived macrophages (MDM)) differentiated into MDM using GM- or M-CSF growth factors and polarized into the M1 state, receiving GM_M1, M_M1, respectively. The total level of H₂O₂ production measured in the presence of horseradish peroxidase differed significantly between two types of macrophages. Only GM_M1 macrophages had a level of H₂O₂ production comparable to neutrophils. GM_M1 appear at the site of inflammation after neutrophils, they continue the work of neutrophils in creating a pro-inflammatory environment: they produce several times more H₂O₂ and pro-inflammatory cytokines than M_M1, which arrive at inflammatory site later. Upon activation, MDM_M1 formed big blot-like and smaller dense spheroid-like aggregates. Activated neutrophils secrete the enzyme myeloperoxidase (MPO), which synthesizes the very potent oxidant hypochlorous acid (HOCl) only in the presence of H₂O₂. Neutrophils are short lived cells, MPO can use H₂O₂ produced by activated cultured MDM to synthesize HOCl at physiologically relevant concentrations to prolong oxidative stress.

To develop a simple and sensitive method for assessing the radical-scavenging activity of lipophilic antioxidants, the decay of the electron spin resonance (ESR) signal of 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl radical (TEMPOL) was investigated as an indicator of radical reactions. The ESR signal of TEMPOL was decreased in ethanol, but not in acetonitrile, by the pyrolysis of 2,2'-azobis(2,4-dimethylvaleronitrile). Signal decay in ethanol was suppressed by degassing and did not occur in the presence of the spin trapping agent 5-(diethoxyphosphoryl)-5-methyl-1-pyrroline-N-oxide (DEPMPO). Spin trapping with DEPMPO showed the formation of peroxyl, alkoxyl, and alkyl radical adducts during the reaction, with peroxyl radical adducts decreasing in the presence of TEMPOL. These results indicate that TEMPOL signal decay occurs by reactions involving ethanol-derived peroxyl radicals. The TEMPOL signal decay was remarkably inhibited by 0.01 mmol/L 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox), which is lower than the Trolox concentration used in the ESR-spin trapping method reported previously. Inhibition by methyl gallate was markedly stronger than Trolox, while the effects of 2,6-di-tert-butyl-p-cresol and resveratrol were minor. The order of inhibition of TEMPOL signal decay by antioxidants correlated to some extent with the order of suppression of peroxyl radical adduct formation by DEPMPO spin trapping. Therefore, the peroxyl radical-scavenging activities of lipid-soluble antioxidants may be evaluated with high sensitivity by examining the inhibitory activity of TEMPOL decay caused by radical reactions in ethanol. The measurement time was less than 5 min.

Sinensetin (SIN for short) is one of the most common polymethoxyflavonoids found in citrus fruits. Recently, it has been extensively studied due to its ability to prevent or treat a wide range of diseases, including diabetes, obesity, neurological disorders, and cancer. Oxidative stress is closely related to the pathogenesis of many diseases. Based on literature research and the results of our previous experiments, we found that flavonoids have significant antioxidant effects. This study found that sinensetin alleviated AAPH-induced oxidative stress in zebrafish and alleviated intestinal and brain damage (including brain neurons, vascular development, and blood-brain barrier integrity). This study is of great significance for further study of the relationship between gut-brain changes and oxidative stress. This study provides a practical and convenient tool for real-time tracking of the protective effect of natural products on the in vivo oxidative stress model induced by AAPH. In addition, it paves the way for the discovery of more antioxidants in the future.

The prognosis of gastric cancer (GC) remains poor due to metastases and resistance to chemotherapy. Ferroptosis is a novel cell death regulation mode characterized by iron dependence and lipid peroxidation. Dioscin, a compound extracted from the Paris polyphylla rhizomes roots, has been shown to have an inhibitory effect on cancers. However, whether it induces ferroptosis to participate in anti-cancer metastasis remains unclear. The ability of gastric cancer cells to invade and migrate was evaluated by wound healing and transwell assays. Malondialdehyde (MDA), glutathione (GSH) assay kit, and dichlorofluorescin diacetate (DCFH-DA) fluorescent probes were used to detect ferroptosis in gastric cancer cells. The expression levels of glutathione peroxidase 4 (GPX4) and solute carrier family 7 member 11 (SLC7A11) were detected by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot methods. The rescue assay was performed by adding Ferrostatin-1 (Fer-1) co-treatment to verify that Dioscin inhibited gastric cancer metastasis by participating in ferroptosis. Dioscin inhibited gastric cancer cells' wound healing, migration, and invasion process. In addition, Dioscin increased the level of reactive oxygen species (ROS) and MDA while decreasing GSH level, and induced ferroptosis of gastric cancer cells. Fer-1, an inhibitor of ferroptosis, could reverse the effect of Dioscin. In terms of mechanism, Dioscin induced ferroptosis through SLC7A11/GPX4 axis and was involved in the regulation of inhibiting metastasis of gastric cancer. These results suggested that Dioscin was involved in anti-cancer metastasis by inducing ferroptosis.

Selenomethionine (SeMet) increases glutathione peroxidase (GPx) activity, a seleno-enzyme with an antioxidant function that counteracts reactive oxygen species (ROS). After ablation, transplant organs generate ROS during irrigation-reperfusion injury. GPx1 can be downregulated during hypoxia in ablated organs. ROS can oxidize proteins, inducing proteolysis, which compromises the transplant outcome. SeMet administration to living donors can decrease proteolysis in transplant organs, improving their preservation. Accordingly, SeMet was administered to rats for 7 days. After this period, the liver, heart, and kidneys were ablated, and proteins extracted at different postmortem intervals (PMI). Total protein analysis showed a lower protein concentration decrease in kidneys and heart from SeMet-supplemented rats after a 6 hs PMI. Molecular weight changes of proteins to proteolysis products (PPs) were studied by size exclusion chromatography (SEC). SeMet decreased PPs (<29.5 kDa) in the liver, kidneys, and heart. Specific analysis of GPx1 proteolysis by affinity chromatography coupled to inductively coupled plasma mass spectrometry (AF-ICP-MS) showed that SeMet administration decreased GPx1 proteolysis 24% in the liver and 16.8% in the heart. SeMet administration reduced the proteolysis velocity of GPx1 (V_GPx1) in heart. SeMet administration to living donors for seven days decreased proteolysis in transplant organs, improving its conservation.

Catechin is a major antioxidant and also shows anti-cancer effect. We have synthesized a catechin analog possessing a planar structure, planar catechin, which has 10-fold larger radical-scavenging activity than the parental (+)-catechin, and demonstrated that the planar catechin showed a significant cytotoxicity in cancer cells. However, the planar catechin has a possibility to lose the innate activity before reaching target cells, because of the higher reactivity with other biological molecules. In this study, we introduced acetyl groups to the phenolic hydroxy groups, which are considered as active sites of the planar catechin, in order to protect from the oxidation of the planar catechin, and examined the effects on cells regarding the toxicity. The acetylated planar catechin showed a remarkable cytotoxicity compared to the original planar catechin, especially in cancer cells, whereas the superoxide scavenging activity of the acetylated planar catechin was weak. On the other hand, after the acetylated planar catechin was treated with esterase, the enhanced superoxide scavenging activity was confirmed by an electron paramagnetic resonance technique. These results indicate that the activity of the planar catechin was maintained by acetylation of the phenolic hydroxy groups and the deprotection by intracellular esterase restored the activity, leading to the induction of the severe cytotoxicity.

Thioredoxin (TRX), a redox-regulatory protein of 12 kDa, plays an essential role in modulating oxidative stress and mediating inflammatory processes. In this study, we compared and analyzed the anti-inflammatory effects of topically applied recombinant human TRX (rhTRX), hydrocortisone, and their combination on murine models of contact dermatitis (CD). Topical application of rhTRX, hydrocortisone, and their synergistic combination notably ameliorated ear edema, reduced neutrophilic infiltration within the ear tissues and suppressed the production of cytokines. We explored the distinct anti-inflammatory mechanisms of rhTRX versus hydrocortisone in phorbol-12-myristate-13-acetate (PMA)-induced PAM212 cells. These treatments collectively downregulated the phosphorylation of p-JNK and p-P38 mitogen-activated protein kinases (MAPKs) in the cells. In addition, rhTRX did not impact the proliferation of CD4+ and CD8+ T lymphocytes. Notably, rhTRX directly downregulated macrophage migration inhibitory factor (MIF), whereas it had no effects on the glucocorticoid-induced leucine zipper (GILZ). Collectively, these findings delineated that rhTRX ameliorated CD by curtailing MAPK pathway, and enhancing glucocorticoid responsiveness through the targeted downregulation of MIF. Consequently, it holds promise as a therapeutic agent for the treatment of CD and warrants further investigation in translational research.

IQOS is a heated tobacco product (HTP) claimed to be less harmful than regular cigarettes. It is unknown whether IQOS emissions contain radicals, cause DNA damage or affect the expression of DNA repair markers in human bronchial epithelial cells. This has important implications as IQOS diffusion is quickly growing, but little toxicological and genotoxic information on its emissions is available. Therefore, we determined the presence of radicals in cigarette smoke extract (CSE) and IQOS extract (IQOSE) by Electron Spin Resonance (ESR) spectroscopy and measured their levels of Tobacco-Specific Nitrosamines (TSNAs) with liquid chromatography-mass spectrometry (LC-MS). Next, DNA damage induced by CSE and IQOSE was determined by means of the Fpg-modified comet assay in human bronchial epithelial cells (BEAS-2B). Finally, the mRNA and protein levels of DNA repair markers in response to both extracts were evaluated. CSE contained significantly more reactive oxygen species (ROS) and TSNAs, whereas more carbon/nitrogen-centered radicals were detected in IQOSE. After 1 h exposure, 3%CSE and 5%IQOSE caused DNA oxidation, while 5%IQOSE also induced DNA strand breaks and alkali-labile sites. Exposure of cells to 1% and 3% IQOSE for 4 h upregulated the expression of DNA repair genes, whereas no significant impact on DNA repair protein levels was observed. This study shows that IQOS extract contains significant amounts of radicals and TSNAs, can induce DNA damage and increase the expression of DNA repair genes in human bronchial epithelial cells. Whether IQOS use is associated with higher risk of developing lung cancer remains to be determined.