Free Radical Research最新文献

Severe acute pancreatitis (SAP) is an inflammatory disorder of the exocrine pancreas associated with high morbidity and mortality. SAP has been proven to trigger mitochondria dysfunction in the pancreas. We found that Deoxyarbutin (dA) recovered impaired mitochondrial function. High-temperature requirement protein A2 (HtrA2), a mitochondrial serine protease upstream of PGC-1α, is charge of quality control in mitochondrial homeostasis. The molecular docking study indicated that there was a potential interaction between dA and HtrA2. However, whether the protective effect of dA against SAP is regulated by HtrA2/PGC-1α remains unknown. Our study in vitro showed that dA significantly reduced the necrosis of primary acinar cells and reactive oxygen species (ROS) accumulation, recovered mitochondrial membrane potential (ΔΨm) and ATP exhaustion, while UCF-101 (HtrA2 inhibitor), and SR-18292 (PGC-1α inhibitor) eliminated the protective effect of dA. Moreover, HtrA2 siRNA transfection efficiently blocked the protective of dA on HtrA2/PGC-1α pathway in 266-6 acinar cells. Meanwhile, dA also decreased LC3II/I ration, as well as p62, and increased Parkin expression, while UCF-101 and Bafilomycin A1 (autophagy inhibitor) reversed the protective effect of dA. Our study in vivo confirmed that dA effectively alleviated severity of SAP by reducing pancreatic edema, plasma amylase, and lipase levels and improved the HtrA2/PGC-1α pathway. Therefore, this is the first study to identify that dA inhibits pancreatic injury caused by oxidative stress, mitochondrial dysfunction, and impaired autophagy in a HtrA2/PGC-1α dependent manner.

Hydrogen sulfide, hydropersulfides, and hydropolysulfides have been revealed to play important physiological roles such as cell signaling and protection against oxidative stress, but the underlying mechanisms and dynamics of action remain elusive. It is generally accepted that these species act by two-electron redox mechanisms, while the involvement of one-electron redox chemistry has received less attention. In this study, the radical-scavenging activity of hydrogen persulfide, hydrogen polysulfides (HS_nH n = 2-4), and diallyl- or dialkyl-sulfides (RS_nR, n = 1-4) was measured. Furthermore, their antioxidant effects against free radical-mediated human plasma lipid peroxidation were assessed by measuring lipid hydroperoxides. It was found that disodium disulfide, trisulfide, and tetrasulfide acted as potent peroxyl radical scavengers, the rate constant for scavenging peroxyl radical being 3.5 × 10⁵, 4.0 × 10⁵, and 6.0 × 10⁵ M^-1 s^-1 in PBS pH 7.4 at 37 °C respectively and that they inhibited plasma lipid peroxidation efficiently, the efficacy is increased with the catenation number. Disodium tetrasulfide was 1.5 times as reactive as Trolox toward peroxyl radical and inhibited plasma lipid peroxidation more efficiently than ascorbate and Trolox. On the other hand, diallyl- and dialkyl-sulfides did not exert significant radical-scavenging activity, nor did they inhibit lipid peroxidation efficiently, except for diallyl tetrasulfide, which suppressed plasma lipid peroxidation, despite less significantly than disodium tetrasulfide. Collectively, this study shows that hydrogen persulfide and hydrogen polysulfides act as potent radical-scavenging antioxidants and that, in addition to two-electron redox mechanisms, one electron redox reaction may also play important role in the in vivo defense against deleterious oxidative stress.

3,4-Dihydroxyphenylacetic acid (DOPAC) and 3-hydroxyphenylacetic acid (OPAC) are the predominant catabolites of quercetin glycosides, such as quercetin 4'-O-β-glucoside from the onion, produced by intestinal microbiota. Although each catabolite has been reported to protect the cells from acetaldehyde-induced cytotoxicity, the effect of their combination remains to be clarified. The purpose of this study was to determine whether the combination of DOPAC and OPAC enhances the resistance against the acetaldehyde-induced oxidative stress in the cultured hepatocytes. The pretreatment of the combination of DOPAC (5 μM) and OPAC (5 μM) showed significant protection against the acetaldehyde- and hydrogen peroxide-induced cytotoxicity, even though each compound at the same concentration did not. This combination also significantly inhibited the intracellular dichlorofluorescin diacetate-detectable reactive oxygen species (ROS) level, whereas the solo treatment did slightly, suggesting that reducing mechanisms of ROS or compounds that enhance ROS production are involved in the cytoprotective effect. The combinatory treatment significantly enhanced the gene expression of not only the aldehyde dehydrogenases (ALDHs), but also glutamate-cysteine ligase, catalytic subunit, the first rate-limiting enzyme of glutathione (GSH) synthesis. Accordingly, both the intracellular GSH level and the total ALDH activity were enhanced by DOPAC plus OPAC. Involvement of GSH in the cytoprotection as well as ALDH up-regulation by the combination was confirmed by the experiments using a GSH biosynthesis inhibitor, buthionine sulfoximine. Taken together, the present results suggested that the quercetin microbiota catabolites concertedly protect the cells from acetaldehyde through a pre-enhanced resistance against oxidative stress by the GSH-dependent up-regulation of ALDHs.

Drug repurposing allows searching for new biological targets, especially against emerging diseases such as Covid-19. Drug colchicine (COL) presents recognized anti-inflammatory action, while the nanotechnology purpose therapies with low doses, efficacy, and decrease the drug's side-effects. This study aims to evaluate the effects of COL and colchicine nanocapsules (NCCOL) on survival, LC50, activity locomotor, and oxidative stress parameters, elucidating the toxicity profile in acute and chronic exposure in Drosophila melanogaster. Three-day-old flies were investigated into groups: Control, 0.001, 0.0025, 0.005, and 0.010 mg/mL of COL or NCCOL. The survival rate, open field test, LC50, oxidative stress markers (reactive species (RS) production, thiobarbituric acid reactive substances), antioxidant enzyme activity (catalase (CAT), superoxide dismutase (SOD), glutathione S-transferase), protein thiols, nonprotein thiols, acetylcholinesterase activity, and cell viability were measured. As a result, acute exposure to the COL decreases the number of crosses in the open field and increases CAT activity. NCCOL reduced RS levels, increased lipoperoxidation and SOD activity. Chronic exposure to the COL and NCCOL in high concentrations implied high mortality and enzymatic inhibition of the CAT and AChE, and only the COL caused locomotor damage in the open field test. Thus, NCCOL again reduced the formation of RS while COL increased. In this comparative study, NCCOL was less toxic to the antioxidant system than COL and showed notable involvement of oxidative stress as one of their toxicity mechanisms. Future studies are needed to elucidate all aspects of nanosafety related to the NCCOL.

Caffeic acid is a phenolic secondary metabolite from plants, which is known for its antioxidant properties. The effective mitigation of methanol-induced oxidative stress by caffeic acid depends on the direct radical scavenging as well as the formation of new metabolites via oxidative degradation. Herein, thermodynamic and kinetic aspects of the oxidative degradation pathway of caffeic acid in the presence of radical CH₃O^• and its isomer, ^•CH₂OH are discussed for the first time, employing density functional theory (DFT). The direct radical scavenging activity of caffeic acid against these radicals is verified via hydrogen atom transfer (HAT) and radical adduct formation (RAF) mechanisms. HAT is predicted to be more feasible than RAF mechanism as per the computed data. Additionally, energetic details of the proposed oxidative degradation pathway of radical adduct intermediates toward the formation of a cyclic metabolite is analyzed. Kinetic studies indicated a significant tunneling contribution to the H abstraction pathways having high activation barriers. Further, our results imply that the newly formed metabolites exhibit comparable antioxidant activity with that of caffeic acid.

Hydrogen peroxide (H₂O₂) is a ubiquitous oxidant produced in a regulated manner by various enzymes in mammalian cells. H₂O₂ reversibly oxidizes thiol groups of cysteine residues to mediate intracellular signaling. While examples of H₂O_2-dependent signaling have been reported, the exact molecular mechanism(s) of signaling and the pathways affected are not well understood. Here, the transcriptomic response of Jurkat T cells to H₂O₂ was investigated to determine global effects on gene expression. With a low H₂O₂ concentration (10 µM) that did not induce an oxidative stress response or cell death, extensive changes in gene expression occurred after 4 h (6803 differentially expressed genes). Of the genes with a greater then 2-fold change in expression, 85% were upregulated suggesting that in a physiological setting H₂O₂ predominantly activates gene expression. Pathway analysis identified gene expression signatures associated with FOXO and NTRK signaling. These signatures were associated with an overlapping set of transcriptional regulators. Overall, our results provide a snapshot of gene expression changes in response to H₂O_2, which, along with further studies, will lead to new insights into the specific pathways that are activated in response to endogenous production of H₂O₂, and the molecular mechanisms of H₂O₂ signaling.

Flavin adenine dinucleotide (FAD) synthase (EC 2.7.7.2), encoded by human flavin adenine dinucleotide synthetase 1 (FLAD1), catalyzes the last step of the pathway converting riboflavin (Rf) into FAD. FLAD1 variations were identified as a cause of LSMFLAD (lipid storage myopathy due to FAD synthase deficiency, OMIM #255100), resembling Multiple Acyl-CoA Dehydrogenase Deficiency, sometimes treatable with high doses of Rf; no alternative therapeutic strategies are available. We describe here cell morphological and mitochondrial alterations in dermal fibroblasts derived from a LSMFLAD patient carrying a homozygous truncating FLAD1 variant (c.745C > T) in exon 2. Despite a severe decrease in FAD synthesis rate, the patient had decreased cellular levels of Rf and flavin mononucleotide and responded to Rf treatment. We hypothesized that disturbed flavin homeostasis and Rf-responsiveness could be due to a secondary impairment in the expression of the Rf transporter 2 (RFVT2), encoded by SLC52A2, in the frame of an adaptive retrograde signaling to mitochondrial dysfunction. Interestingly, an antioxidant response element (ARE) is found in the region upstream of the transcriptional start site of SLC52A2. Accordingly, we found that abnormal mitochondrial morphology and impairments in bioenergetics were accompanied by increased cellular reactive oxygen species content and mtDNA oxidative damage. Concomitantly, an active response to mitochondrial stress is suggested by increased levels of PPARγ-co-activator-1α and Peroxiredoxin III. In this scenario, the treatment with high doses of Rf might compensate for the secondary RFVT2 molecular defect, providing a molecular rationale for the Rf responsiveness in patients with loss of function variants in FLAD1 exon 2.HIGHLIGHTSFAD synthase deficiency alters mitochondrial morphology and bioenergetics;FAD synthase deficiency triggers a mitochondrial retrograde response;FAD synthase deficiency evokes nuclear signals that adapt the expression of RFVT2.

In-vitro and animal studies demonstrate that lipid peroxidation plays an important role in the pathogenesis of type 2 diabetes (T2D). However, human data from prospective studies are limited and contradictory. We used data originally collected in two nested case-control studies of cancer to prospectively evaluate whether systemic levels of lipid peroxidation were associated with incidence of T2D in 1917 women who were 40-70 years old and diabetes-free at baseline. Lipid peroxidation was measured by urinary F₂-isoprostanes (F₂-IsoPs) and its major metabolite 2,3-dinor-5,6-dihydro-15-F_2t-IsoP (F₂-IsoP-M) with GC/NICI-MS assays. The Cox regression model was used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) for incident T2D. After a median follow-up of 10.1 years, 187 women were diagnosed with T2D. Urinary concentrations of both F₂-IsoPs and F₂-IsoP-M were significantly higher in T2D cases than in non-cases. Both biomarkers were positively associated with subsequent risk of T2D in multivariable-adjusted Cox models. When further adjusted for body mass index (BMI), the positive association with F₂-IsoP-M was attenuated and no longer statistically significant, whereas the association with F₂-IsoPs remained (P for overall significance < 0.001). HR for T2D was 1.68 (95% CI: 1.13, 2.51) for the highest vs the lowest quartile of F₂-IsoPs. Moreover, this association appeared more pronounced among women with higher BMI. In summary, our study suggests that F₂-IsoPs could be of significance in T2D risk prediction among middle-aged and elderly women.

The molecular mechanisms underlying the development of pulmonary fibrosis remain unknown, and effective treatments have not yet been developed. It has been shown that oxidative stress is involved in lung fibrosis. Oxidized diacylglycerol (DAG) produced by oxidative stress is thought to play an important role in lung fibrosis. This study assessed the effect of oxidized DAG in an animal model of pulmonary fibrosis induced by aspiration of bleomycin (BLM) into the lungs. The inhibitory effect of ebselen on pulmonary fibrosis was also investigated. In lung fibrotic tissue induced by BLM, an increase in lipid peroxides and collagen accumulation was observed. Moreover, the levels of oxidized DAG, which has strong protein kinase C (PKC) activation activity, were significantly increased over time following the administration of BLM. Western blotting showed that phosphorylation of PKCα and δ isoforms was increased by BLM. Oral administration of ebselen significantly suppressed the increase in oxidized DAG induced by BLM and improved lung fibrosis. PKCα and δ phosphorylation were also significantly inhibited. The mRNA expression of α-smooth muscle actin and collagen I (marker molecules for fibrosis), as well as the production of transforming growth factor-β and tumor necrosis factor-α(a potentially important factor in the fibrotic process), were increased by BLM and significantly decreased by ebselen. The administration of BLM may induce lipid peroxidation in lung tissue, while the oxidized DAG produced by BLM may induce overactivation of PKCα and δ, resulting in the induction of lung fibrosis.

Plasma, the fourth state of matter could be artificially generated at room temperature under atmospheric pressure - termed as cold atmospheric plasma (CAP). The reactive oxygen and nitrogen radicals emanated during plasma discharge accord manifold applications in medicine and have proven clinical applications in cancer treatment, dentistry, and dermatology. Developments in the field termed "Plasma medicine" has inclined research toward its prospects in immunotherapy. Controlled generation of reactive oxygen and nitrogen radicals during plasma formation produces oxidative stress on tissue of concern, selectively and activates a number of cytological and molecular reactions, triggering immunological response. Plasma treatment induces immunogenic cell death (ICD) in tumor cells and elicits enhanced adaptive and systemic immune response with memory cells, conferring better defense to cancer. HIV inactivation, reduced viral replication, reversal of latency in HIV-infected cells, and augmented infected cell opsonization has been observed with CAP treatment. Plasma-treated medium has shown to deactivate Herpes simplex virus (HSV-1) in human corneal explants and epithelial cells, and lessen the severity of herpes simplex keratitis. Perception of cellular changes that triggers innate and adaptive immune response during CAP treatment is quintessential for understanding and expansion of research in this arena. This review mentions the inimitable properties of plasma that makes it a safe and sensitive immunotherapeutic tool. The methods of plasma generation relied for the purpose are elucidated. The cellular mechanism of immunological stimulation in cancer, HIV, and keratitis during CAP treatment is detailed. The future prospects and challenges are briefly addressed.HighlightsReactive oxygen and nitrogen radicals produced by cold atmospheric plasma (CAP) triggers oxidative stress in exposed cells.Cells in oxidative stress incite immunological response that could be suitably manipulated for immunotherapy.The role of reactive radicals and methods of plasma generation for immunotherapy is elucidated.The cellular and molecular cascade of reactions leading to immunological cell death in cancer cells is detailed.The mechanism of HIV inactivation and reduced infection; further, deactivation of HSV in Herpes keratitis in intact human corneal explants is also described.