Free Radical Research最新文献

Diamine oxidase (DAO) histamine-degradation rates are compromised in plasma of mastocytosis patients during severe mast cell activation events. Mast cell-liberated histamine induces the release of nitric oxide (NO) close to DAO extracellular storage sites. We hypothesized that NO inhibits DAO activity. Recombinant human DAO activity was measured after incubation with NO-releasing NONOates (R¹R²N-(NO^-)-N = O). Topaquinone reactivity was quantified by absorption measurements and by mass spectrometry. Several murine models of NO-production were assessed for DAO activity inhibition in vivo. Nitric oxide released from NONOates dose dependently and irreversibly inhibited DAO activity. The NO scavengers Trolox (Vitamin E derivative) and 2-(4-Carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (C-PTIO), the reversible DAO inhibitors diminazene and ciproxifan, the substrates histamine (EC₅₀ = 32 µM) and putrescine (EC₅₀ = 39 µM), heparin whole blood and plasma protected DAO from inhibition. Nitric oxide reduced the reactivity of topaquinone to phenylhydrazine by 90%. None of the NO producing in vivo models showed DAO inhibition in plasma or tissue. Nitric oxide is a potent irreversible DAO inhibitor in vitro representing the first discovered natural inhibitor for this enzyme. Endogenous mouse DAO inhibition in vivo could not be demonstrated. The true nature of human DAO activity inhibition during severe mastocytosis events remains unknown.

The synthetic naringenin derivative (2S)-8-carboxymethylnaringenin (CMN) was developed for the treatment of bacterial and viral respiratory infections. There are indications that CMN may act as an antioxidant, however, no studies have been conducted in this regard. This work is aimed at assessing the antiradical capacity of CMN against various physiologically relevant species in physiological environments by using thermodynamic and kinetic calculations. According to the results, CMN only exhibits modest HOO^• antiradical activity in lipid medium, modeled here as pentyl ethanoate solvent, with an overall rate constant (k_overall) of 2.01 × 10² M^-1 s^-1. However, significant antiradical activity is predicted for the aqueous medium (k_overall = 2.60 × 10⁵ M^-1s^-1) that is equivalent to the activity of the reference antioxidant Trolox. In a screen performed on a range of radicals, HO^•, NO₂, SO₄^•-, N₃^•, CH₃O^•, CCl₃O^•, CH₃OO^•, and CCl₃OO^• were also successfully scavenged by CMN in water at physiological pH. Therefore, other than a potent drug, CMN is also a good antioxidant in polar environments.

Ferroptosis characterized by iron-dependent lipid peroxidation induced by traumatic brain injury (TBI) is an important factor that aggravates diseases. Studies have shown that tetrahydrocurcumin (THC) has neuroprotective effects in brain injury. However, whether THC inhibits neurocyte ferroptosis after TBI and its mechanism remains unclear. To investigate this, a weight-drop model in rats and H₂O₂ induced oxidative stress model in SH-SY5Y cells were established, and THC was used for treatment. Immunohistochemical staining showed that iron deposition reached its peak at 8th day after TBI. We found that THC remarkably inhibited iron accumulation in the cortical cortex and corpus callosum, improved neurological damage, reduced acute cerebral edema, weight loss, oxidative stress, and inflammation. Furthermore, the activity of iPLA2β was significantly reduced, and phosphorylation of p38 was increased after TBI, while THC alleviated the decrease in iPLA2β activity and increase in the level of P-p38. It confirmed that THC effectively mitigated ferroptosis, while iPLA2β inhibitor s-BEL could reverse the effects of THC on ferroptosis in vivo and in vitro experiments. In addition, SB202190 which is an inhibitor of p38 could enhance THC protection and lessen formation of ferroptosis-related proteins in cells. In conclusion, these findings suggested that THC may promote neurological function recovery after TBI by inhibiting neuron ferroptosis via activity of iPLA2β/P-p38.

Little is known regarding the effects high-intensity training performed in hypoxia on the oxidative stress and antioxidant systems. The aim of this study was to assess the potential effect of 4 weeks of repeated sprint training in hypoxia (RSH) on the redox balance. Forty male well-trained cyclists were matched into two different interventions (RSH, n = 20) or in normoxia, RSN, n = 20) and tested twice (before (Pre-) and after (Post-) a 4-week of training) for performance (repeated sprint ability (RSA) test), oxidative stress, and antioxidant status. Antioxidant enzyme activity (Superoxide Dismutase, Glutathione Peroxidase, and catalase), NO metabolites (NOx: nitrites and nitrates), ferric reducing antioxidant power, Malondialdehyde (MDA), nitrotyrosine, and carbonyls were measured in plasma. At Post-, MDA, and carbonyls increased (p < 0.05) in the RSN group both at rest (+90.6%) and also acutely in response to RSA (+22.9%); but not in RSH. At Post-, in the RSH group, catalase increased (p < 0.05) both at rest (+44.7%) and in response to the RSA test (+66.3%). At Post-, SOD, and nitrotyrosine decreased after RSA and at rest, regardless of the group (p = 0.0012 and p = 0.0413, respectively). At Post-, NOx decreased after the RSA test, regardless of the group (p < 0.05). In conclusion, several weeks of RSH training limits the increase in oxidative stress markers both at rest and in response to RSA test. Moreover, such training downregulated SOD activity, possibly due to an overproduction of reactive oxygen species. These findings could constitute a paradigm shift with a better enzymatic adaptation after RSH concomitant with a distinct reactive oxygen species (ROS) production between RSH and RSN.

Patients with hypoxemia require high-concentration oxygen therapy. However, prolonged exposure to oxygen concentrations 21% higher than physiological concentrations (hyperoxia) may cause oxidative cellular damage. Pulmonary alveolar epithelial cells are major targets for hyperoxia-induced oxidative stress. In this study, we evaluated the therapeutic potential of the antioxidant N-acetyl-L-cysteine (NAC) for preventing hyperoxia-induced cell death. In vitro experiments were performed using the human lung cancer cell line A549. In brief, NAC-treated and untreated cells were exposed to various concentrations of oxygen (hyperoxia) for different durations. The results indicated that hyperoxia inhibited proliferation and caused cell cycle arrest in A549 cells. It also induced necrosis and autophagy. Furthermore, hyperoxia increased intracellular reactive oxygen species levels and altered mitochondrial membrane potential. Co-treatment with NAC improved the survival of cells exposed to 95% oxygen for 24 h. Experiments performed using a neonatal rat model of acute lung injury confirmed that hyperoxia induced an autophagic response. This study provides evidence for hyperoxia-induced autophagy both in vitro and in vivo. NAC can protect A549 cells from death induced by short-term hyperoxia. Our findings may inform protective strategies against hyperoxia-induced injury in developing lungs-for example, bronchopulmonary dysplasia in premature infants.

Free radicals have been implicated in the pathogenesis of cancer along with cardiovascular, neurodegenerative, pulmonary and inflammatory disorders. Further, the relationship between oxidative stress and disease is distinctively established. Clinical trials using anti-oxidants for the prevention of disease progression have indicated some beneficial effects. However, these trials failed to establish anti-oxidants as therapeutic agents due to lack of efficacy. This is attributed to the fact that living systems are under dynamic redox control wherein their redox behavior is compartmentalized and simple aggregation of redox couples, distributed throughout the system, is of miniscule importance while determining their overall redox state. Further, free radical metabolism is intriguingly complex as they play plural roles segregated in a spatio-temporal manner. Depending on quality, quantity and site of generation, free radicals exhibit beneficial or harmful effects. Use of nonspecific, non-targeted, general ROS scavengers lead to systemic elimination of all types of ROS and interferes in cellular signaling. Failure of anti-oxidants to act as therapeutic agents lies in this oversimplification of extremely dynamic cellular redox environment as a static and non-compartmentalized redox state. Rather than generalizing the term "oxidative stress" if we can identify the "type of oxidative stress" in different types of diseases, a targeted and more specific anti-oxidant therapy may be developed. In this review, we discuss the concept of redox dynamics, role and type of oxidative stress in disease conditions, and current status of anti-oxidants as therapeutic agents. Further, we probe the possibility of developing novel, targeted and efficacious anti-oxidants with drug-like properties.

Reactive oxygen species (ROS) produced by NADPH oxidase promote contraction of peripheral arteries, which is especially pronounced in early postnatal period in comparison to adulthood, but the mechanisms of such vasomotor influence are poorly understood. We tested the hypothesis that Rho-kinase and protein kinase C (PKC) mediate procontractile influence of NADPH oxidase derived ROS in peripheral artery of early postnatal rats. In addition, we evaluated the involvement Src-kinase and L-type voltage-gated Ca²⁺ channels (LTCC) into procontractile influence of ROS, produced by NADPH oxidase, because of their known interplay with Rho-kinase and PKC pathways. Saphenous arteries from 11- to 15-day-old male rats were studied using quantitative PCR, isometric myography and lucigenin-enhanced chemiluminescence. Arterial tissue of early postnatal rats contained Nox2, Nox4, Duox1 and Duox2 mRNAs, among which Nox2 mRNA was the most abundant. Pan-NADPH oxidase inhibitor VAS2870 (10 µM) significantly reduced arterial contractile responses to methoxamine. The inhibitors of Rho-kinase (Y27632, 3 µM), PKC (GF109203X, 10 µM) and Src-kinase (PP2, 10 µM), as well as LTCC blockers (nimodipine, 0.1 µM, and verapamil, 0.1 μM) also reduced methoxamine-induced contraction. Importantly, the effect of VAS2870 persisted in the presence of Rho-kinase, PKC or Src-kinase inhibitors, but not in the presence of LTCC blocker. Notably, the blockade of LTCC did not affect either basal or NADPH-induced O₂^•- production. Our data show that LTCC, but not Rho-kinase, PKC or Src-kinase are involved into procontractile effect of ROS, produced by NADPH oxidase, in saphenous artery of young rats. Сalcium influx through LTCC does not activate ROS production by NADPH oxidase.

Cancer genome sequencing studies have identified somatic mutations in the KEAP1/NRF2 pathway. In an effort to identify novel NRF2 small molecule inhibitor(s), we have screened a natural compound library comprising 1330 chemicals in A549-ARE-GFP-luciferase cells and identified that narciclasine significantly inhibits NRF2-dependent luciferase activity. Narciclasine suppressed the expression of NRF2 and NRF2 target genes, caused significant oxidative stress, and sensitized cisplatin-mediated apoptosis in A549 cells. In addition, we have observed that WD Repeat Domain 43 (WDR43) serves as a direct target of narciclasine for the inhibition of NRF2 as narciclasine binds to recombinant WDR43 in vitro and silencing WDR43 attenuated the inhibition of NRF2 by narciclasine in A549 cells. Finally, we observed that administration of narciclasine significantly decreased the growth of A549 xenografts. Together, our results demonstrate that the inhibition of NRF2 by narciclasine is mediated by WDR43 and future studies are necessary to elucidate the exact mechanism of how WDR43 mediates the inhibition of NRF2 by narciclasine.

This research investigates the interplay between Reactive Oxygen Species (ROS) and Apelin (APLN) in regulating autophagy, with implications for placental cell senescence and apoptosis in pre-eclampsia (PE). We manipulated APLN expression using sgRNA to study its effects on ROS levels and subsequent cellular responses. Our findings reveal that APLN overexpression elevates ROS production, accelerating cellular senescence and apoptosis. In contrast, silencing APLN enhances autophagy, thereby diminishing cellular aging and apoptosis. These outcomes were confirmed in vitro and in vivo experiments, establishing a causative relationship between ROS-mediated APLN modulation and altered placental cell dynamics in PE. The results suggest potential therapeutic targets within the ROS and APLN pathways to alleviate detrimental changes in the placenta, offering new strategies for the clinical management of PE. This study emphasizes the crucial role of autophagy in placental health and sets the stage for future investigations into therapeutic interventions for pregnancy-related complications.

Naturally occurring vitamin E is a lipophilic plant-derived molecule corresponding to the 2 R forms of alpha-tocopherol. A series of natural analogs or tocochromanols are present in nature, including β-, γ- and δ-tocopherol (βT, γT, δT), the corresponding tocotrienols (αTE, βTE, γTE, δTE) and tocomonoenols. Differences between these analogs as lipophilic antioxidants and modulators of molecular processes suggest specific therapeutic properties against various disorders associated with acute and chronic inflammation. However, hepatic metabolism of these compounds via cytochrome P450-initiated side chain ω-oxidation involves the production of long-chain metabolites (LCMs) followed by intermediate (ICMs) and short-chain metabolites (SCMs), respectively. Despite the initial studies indicating these metabolites as catabolic-end products, recent findings identify their importance in providing biological functions. In this scope, LCMs, especially 13'-carboxychromanols (13'-COOHs), have been reported to hold stronger anti-inflammatory capacity than their unmetabolized precursors due to their ability to inhibit 5-lipoxygenase and cyclooxygenase-catalyzed eicosanoid formation, as well as their modulation of the pro-inflammatory transcriptional protein nuclear factor κB (NF-κB). Also, these LCMs have been reported to enhance detoxification and lipid metabolism pathways associated with cellular inflammation by modulating the nuclear receptors peroxisome proliferator-activated receptor-γ (PPARγ) and pregnane x receptor (PXR). These properties of LCMs will be described in this narrative review article focusing on recent information regarding their bioavailability, anti-inflammatory effects, and mechanisms of action in acute and chronic inflammatory disorders.