Nuclear factor erythroid 2-related factor 2 antioxidant response element pathways protect bovine mammary epithelial cells against H2O2-induced oxidative damage in vitro

The experiment was conducted to determine the role of nuclear factor (erythroid-derived 2)-like factor 2 (NFE2L2, formerly Nrf2) antioxidant response element (ARE) pathway in protecting bovine mammary epithelial cells (BMEC) against H₂O₂-induced oxidative stress injury. An NFE2L2 small interfering RNA (siRNA) interference or a pCMV6-XL5-NFE2L2 plasmid fragment was transfected to independently downregulate or upregulate expression of NFE2L2. Isolated BMEC in triplicate were exposed to H₂O₂ (600 μM) for 6 h to induce oxidative stress before transient transfection with scrambled siRNA, NFE2L2-siRNA, pCMV6-XL5, and pCMV6-XL5-NFE2L2. Cell proliferation, apoptosis and necrosis rates, antioxidant enzyme activities, reactive oxygen species (ROS) and malondialdehyde (MDA) production, protein and mRNA expression of NFE2L2 and downstream target genes, and fluorescence activity of ARE were measured. The results revealed that compared with the control, BMEC transfected with NFE2L2-siRNA3 had proliferation rates that were 9 or 65% lower without or with H₂O₂, respectively. These cells also had apoptosis and necrosis rates that were 27 and 3.5 times greater with H₂O₂ compared with the control group, respectively. In contrast, transfected pCMV6-XL5-NFE2L2 had proliferation rates that were 64.3% greater or 17% lower without or with H₂O₂ compared with the control group, respectively. Apoptosis rates were 1.8 times lower with H₂O₂ compared with the control. In addition, compared with the control, production of ROS and MDA and activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase (CAT), and glutathione-S-transferase (GST) increased markedly in cells transfected with pCMV6-XL5-NFE2L2 and without H₂O₂. However, compared with the control, production of ROS and MDA and activity of CAT and GSH-Px increased markedly, whereas activities of SOD and GST decreased in cells transfected with pCMV6-XL5-NFE2L2 and incubated with H₂O₂. Compared with the control, cells transfected with NFE2L2-siRNA3 with or without H₂O₂ had lower production of ROS and MDA and activity of SOD, CAT, GSH-Px, and GST. Cells transfected with pCMV6-XL5-NFE2L2 with or without H₂O₂ had markedly higher protein and mRNA expression of NFE2L2, heme oxygenase-1 (HMOX-1), NADH quinone oxidoreductase 1, glutamate cysteine ligase catalytic subunit, and glutamyl cystine ligase modulatory subunit compared with the control incubations. Cells transfected with NFE2L2-siRNA3 without or with H₂O₂ had markedly lower protein and mRNA expression of NFE2L2, HMOX-1, NADH quinone oxidoreductase 1, glutamyl cystine ligase modulatory subunit, and glutamate-cysteine ligase catalytic subunit compared with the control incubations. In addition, expression of HMOX-1 was 5.3-fold greater with H₂O₂ compared with the control. Overall, results indicate that NFE2L2 plays an important role in the NFE2L2-ARE pathway via the control of HMOX-1. The relevant mechanisms in vivo merit further study.     

Neuroprotective effect of Allium hookeri against H2O2-induced PC12 cell cytotoxicity by reducing oxidative stress

Food Science and Biotechnology - In this study, the anti-oxidative and neuro-protective effects of ethanolic extracts of the dried roots of Allium hookeri were investigated. Total phenolic contents...     

Antioxidant activity and protective effect of methyl gallate against t-BHP induced oxidative stress through inhibiting ROS production

Food Science and Biotechnology - Non-alcoholic fatty liver disease (NAFLD) is one of the major diseases of chronic liver damage caused by oxidative stress. In this study, we investigated...     

富锶茶多糖提取物的抗氧化活性及其对H2O2诱导LO2细胞氧化损伤保护研究

目的 探明富锶茶多糖最佳提取工艺,并分析其体外抗氧化活性及对H2O2诱导LO2细胞氧化损伤的保护作用。方法 本研究采用热水超声辅助法从茶叶中提取富锶茶多糖,通过Box-Behnken响应面实验法对富锶茶多糖的提取工艺条件进行了优化;以1,1-二苯基-2-三硝基苯肼(1,1-diphenyl-2-picrylhydrazyl, DPPH)自由基、羟基自由基(·OH)、2,2’-联氮-二(3-乙基-苯并噻唑啉-6-磺酸)二铵盐[2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) ammonium salt, ABTS]阳离子自由基的清除能力和Fe3+的还原能力来为指标,分析富锶茶多糖的体外抗氧化活性;并以过氧化氢(H2O2)建立LO2细胞损伤模型,研究富锶茶多糖对LO2细胞氧化应激损伤的改善机制。结果 富锶茶多糖的最佳的提取工艺条件为：浸提时间57 min、料液比1:25 g/mL、提取温度67℃,富锶茶多糖得率为3.50%±0.12%。在体外抗氧化方面,富锶茶多糖对DPPH自由基、ABTS阳离子自由基、·OH和对Fe3+的还原能力具有较好的清除能力;在改善LO2细胞氧化应激损伤方面,随着多糖质量浓度升高,细胞存活率也显著提高,当多糖质量浓度为50 μg/mL时,细胞存活率达到99.5%;在清除机体过氧化机制上,相对于模型组,超氧化物歧化酶(superoxide dismutase, SOD)在低、中、高实验组中均有所增强,氧化氢酶(catalase, CAT)活力在中、高实验组中有显著提高,从细胞水平表明富锶茶多糖对LO2细胞氧化损伤具有明显的改善作用。结论 富锶茶多糖具有良好的抗氧化性以及对H2O2诱导LO2细胞氧化损伤有很好的保护作用,为富锶茶多糖功能性产品开发提供了理论基础。     

Protective effect of volatile extract from Pinus densiflora against aflatoxin B1-induced oxidative stress in HepG2 cells

Pinus densiflora is one of the traditional medicinal plants found in the East Asia, which has a diversity of biological activities including antioxidant effect. The protective effects of a volatile extract from Pinus densiflora (VEPN) against aflatoxin B₁ (AFB₁)-induced oxidative stress were investigated in human hepatoma cell line, HepG2. Treatment of HepG2 with VEPN significantly reduced the levels of intracellular reactive oxygen species, thiobarbituric acid reactive substances and 8-hydroxy-2′-deoxyguanosine elevated by AFB₁, but it increased the level of reduced glutathione. These results indicate that VEPN may afford cytoprotection by attenuating AFB₁-induced oxidative stress.     

Research progress on the regulation of oxidative stress by phenolics: the role of gut microbiota and Nrf2 signaling pathway

In recent years, the increase in high-calorie diets and sedentary lifestyles has made obesity a global public health problem. An unbalanced diet promotes the production of proinflammatory cytokines and causes redox imbalance in the body. Phenolics have potent antioxidant activity and cytoprotective ability. They can scavenge free radicals and reactive oxygen species, and enhance the activity of antioxidant enzymes, thus combating the body's oxidative stress. They can also improve the body's inflammatory response, enhance the enzyme activity of lipid metabolism, and reduce the contents of cholesterol and triglyceride. Most phenolics are biotransformed and absorbed into the blood after the action by gut microbiota; these metabolites then undergo phase I and II metabolism and regulate oxidative stress by scavenging free radicals and increasing expression of antioxidant enzymes. Phenolics induce the expression of genes encoding antioxidant enzymes and phase II detoxification enzymes by stimulating Nrf2 to enter the nucleus and bind to the antioxidant response element after uncoupling from Keap1, thereby promoting the production of antioxidant enzymes and phase II detoxification enzymes. The absorption rate of phenolics in the small intestine is extremely low. Most phenolics reach the colon, where they interact with the microbiota and undergo a series of metabolism. Their metabolites will reach the liver via the portal vein and undergo conjugation reactions. Subsequently, the metabolites reach the whole body to exert biological activity by traveling with the systemic circulation. Phenolics can promote the growth of probiotics, reduce the ratio of Firmicutes/Bacteroidetes (F/B), and improve intestinal microecological imbalance. This paper reviews the nutritional value, bioactivity, and antioxidant mechanism of phenolics in the body, aiming to provide a scientific basis for the development and utilization of natural antioxidants and provide a reference for elucidating the mechanism of action of phenolics for regulating oxidative stress in the body. © 2023 Society of Chemical Industry.     

Evaluation of pre-slaughter low-current/high-frequency electrical stunning on lipid oxidative stability,antioxidant enzyme activity and gene expression of mitogen-activated protein kinase/nuclear factor erythroid 2-related factor 2 (MAPK/Nrf2) signalling pathway in thigh muscle of broilers

This study was aimed to evaluate the effects of pre-slaughter low-current/high-frequency (LH) electrical stunning (ES) on lipid oxidative stability, antioxidant enzyme activity and gene expression of mitogen-activated protein kinase/nuclear factor erythroid 2-related factor 2 (MAPK/Nrf2) signalling pathway in thigh muscle of broilers. Eighteen birds were randomly allocated to the following three treatments with six replicates per treatment and one bird per replicate: without stunning (control); water-bath ES with sinusoidal alternating LH (86 mA, 1000 Hz, LHES) or high current/low frequency (HL) (130 mA, 60 Hz, HLES). Stunning methods did not affect malondialdehyde level (d 0 ~ d 9) or antioxidant enzymes’ activity at d 0 ~ d 2. LHES enhanced glutathione S-transferase activity at d 3 and gene expression of MAPKs and Nrf2 compared with HLES. In conclusion, LHES enhanced gene expression of MAPK/Nrf2 pathway, whereas had no superiority over HLES in lipid oxidative stability (4 °C, 9 days) of thigh muscle in broilers.     

Involvement of oxidative stress induction in Na+ toxicity and its relation to the inhibition of a Ca2+ -dependent but calcineurin-independent mechanism in Saccharomyces cerevisiae

Uridine 5'-hexadecylphosphate (UMPC16) inhibited the growth of Saccharomyces cerevisiae under a hypersaline stress condition with Na+ more strongly than the calcineurin inhibitor cyclosporine A (CsA). Additional Ca2+ supplementation similarly suppressed the inhibitory activities of UMPC16 and CsA on yeast cell growth in a medium with Na+. UMPC16, but not CsA, accelerated mitochondrial reactive oxygen species (ROS) generation in combination with Na+, suggesting its inhibition of a Ca2+ -dependent but calcineurin-independent mechanism for protection against Na+ toxicity.     

Effect of camel milk protein hydrolysates against hyperglycemia,hyperlipidemia, and associated oxidative stress in streptozotocin (STZ)-induced diabetic rats

This study investigated the effect of camel milk protein hydrolysates (CMPH) at 100, 500 and 1,000 mg/kg of body weight (BW) for 8 wk on hyperglycemia, hyperlipidemia, and associated oxidative stress in streptozotocin-induced diabetic rats. Body weights and fasting blood glucose levels were observed after every week until 8 wk, and oral glucose tolerance test (OGTT) levels and biochemical parameters were evaluated after 8 wk in blood and serum samples. Antioxidant enzyme activity and lipid peroxidation in the liver were estimated, and histological examination of the liver and pancreatic tissues was also conducted. Results showed that CMPH at 500 mg/kg of BW [camel milk protein hydrolysate, mid-level dosage (CMPH-M)] exhibited potent hypoglycemic activity, as shown in the reduction in fasting blood glucose and OGTT levels. The hypolipidemic effect of CMPH was indicated by normalization of serum lipid levels. Significant improvement in activity of superoxide dismutase and catalase, and reduced glutathione levels were observed, along with the attenuation of malondialdehyde content in groups fed CMPH, especially CMPH-M, was observed. Decreased levels of liver function enzymes (aspartate aminotransferase and alanine aminotransferase) in the CMPH-M group was also noted. Histology of liver and pancreatic tissue displayed absence of lipid accumulation in hepatocytes and preservation of β-cells in the CMPH-M group compared with the diabetic control group. This is the first study to report anti-hyperglycemic and anti-hyperlipidemic effect of CMPH in an animal model system. This study indicates that CMPH can be suggested for its therapeutic benefits for hyperglycemia and hyperlipidemia, thus validating its use for better management of diabetes and associated comorbidities.     

Free radical scavenging activity and comparative proteomic analysis of antioxidative protein against H2O2-induced oxidative stress in neuronal cells

Artemisia annua was enzymatically hydrolyzed by five proteases and seven carbohydrases. All enzymatic extracts scavenged DPPH, hydroxyl and alkyl radicals. Especially, the Protamex among the various proteases and Maltogenase among the various carbohydrases extracts exhibited the highest scavenging activity on hydroxyl radical. The extracts of A. annua clearly reduced neuronal cell death from H₂O₂-induced damage. In addition, a proteomic analysis, two-dimensional electrophoresis (2-DE) and matrix assisted laser desorption ionisation-time of flight/time of flight (MALDI-TOF/TOF) was used to identify the proteins of the neuronal cells whose expressions were or were not altered by the treatment of the Maltogenase extracts which showed the highest hydroxyl radical scavenging activity among all enzymatic extracts for 24 h. The protein characterisation revealed that translation elongation factor Tu (EF-Tu), Immunoglobulin E (IgE) and voltage-dependent anion channel 1 (VDAC-1) were involved in the cell survival effects against H₂O₂-induced apoptosis. These results suggest that EF-Tu, IgE and VDAC-1 have an important role in the reduction of neuronal apoptosis by oxidative stress, and the enzymatic extracts of A. annua shows potent antioxidative activities by regulating EF-Tu, IgE and VDAC-1.     

Role of antioxidant enzymatic defences against oxidative stress H(2)O(2) and the acquisition of oxidative tolerance in Candida albicans

In Candida albicans, trehalose plays an essential role as a protector of cell integrity against oxidative challenge. A double homozygous mutant, tps1/tps1, deficient in trehalose synthesis, displayed severe cell mortality when exposed to high H(2)O(2) concentrations, compared with its congenic parental (CAI-4) strain (Alvarez-Peral et al., 2002). We have examined the putative role of a set of well-known antioxidant enzymes as components of the defence mechanism against oxidative challenges. When exposed to mild non-lethal oxidative treatment (0.5 mM H(2)O(2)), a significant induction of catalase, glutathione reductase (GR), and Cu,Zn-superoxide dismutase (SOD) was recorded in tps1/tps1 exponential cultures. However, in CAI-4 cells, subjected to the same conditions, there was only a clear activation of catalase, Mn-SOD and Cu,Zn-SOD activities. The degree of activation was always much more pronounced in the trehalose-deficient mutant than in its wild-type counterpart, except for Mn-SOD activity. After exposure to severe oxidative stress (50 mM H(2)O(2)) only GR and catalase activities increased in tps1/tps1 cultures, whereas in CAI-4 cells GR but not catalase was induced. In both cell strains, 50 mM H(2)O(2) caused inhibition of the Mn- and Cu,Zn-SOD isozymes, this inhibition being more pronounced in tps1/tps1 cells. C. albicans is able to acquire adaptive oxidative tolerance by pretreatment with a low non-stressing concentration of H(2)O(2) before exposure to a drastic oxidative challenge. When these antioxidant activities were measured during the adaptive response, a greater degree of enzymatic antioxidant induction was consistently observed in the tps1/tps1 mutant with respect to the CAI-4 strain. Together with a higher intrinsic sensitivity of tps1/tps1 cells, we suggest that this unexpected increase might be explained in terms of a compensatory mechanism to overcome the lack of endogenous trehalose upon drastic oxidative exposure, although this induction was not sufficient to improve the percentage of cell viability.     

Quercetin and its metabolites protect hepatocytes against ethanol-induced oxidative stress by activation of Nrf2 and AP-1

Food Science and Biotechnology - Alcohol-induced liver disease progresses due to increased reactive oxygen species (ROS) and cellular lipid peroxidation. Quercetin is a flavonoid with strong...