Intracellular Antioxidant Enzymes Research Articles

Divergent antioxidant capacity of human islet cell subsets: A potential cause of beta-cell vulnerability in diabetes and islet transplantation.

BackgroundType 1 and Type 2 diabetes mellitus (T1DM and T2DM) are caused by beta(β)-cell loss and functional impairment. Identification of mechanisms of β-cell death and therapeutic interventions to enhance β-cell survival are essential for prevention and treatment of diabetes. Oxidative stress is a common feature of both T1DM and T2DM; elevated biomarkers of oxidative stress are detected in blood, urine and tissues including pancreas of patients with DM. Islet transplantation is a promising treatment for diabetes. However, exposure to stress (chemical and mechanical) and ischemia-reperfusion during isolation and transplantation causes islet loss by generation of reactive oxygen species (ROS). Human intracellular antioxidant enzymes and related molecules are essential defenses against ROS. Antioxidant enzyme levels including superoxide dismutase (SOD), catalase, and glutathione peroxidase (GPX) have been shown to be low in islet cells. However, little is known about the expression and function of antioxidant enzymes within islet cell subsets. We evaluated the expression of the key antioxidant enzymes in β- and alpha(α)-cell and accessed effects of oxidative stress, islet isolation and transplantation on β/α-cell ratio and viability in human islets.MethodsHuman pancreata from T1DM, T2DM and non-diabetic deceased donors were obtained and analyzed by confocal microscopy. Isolated islets were (I) transplanted in the renal sub-capsular space of streptozotocin-induced diabetic nude mice (in vivo bioassay), or (II) exposed to oxidative (H2O2) and nitrosative (NO donor) stress for 24 hrs in vitro. The ratio, % viability and death of β- and α-cells, and DNA damage (8OHdG) were measured.Results and conclusionsCatalase and GPX expression was much lower in β- than α-cells. The β/α-cell ratio fells significantly following islet isolation and transplantation. Exposure to oxidative stress caused a significantly lower survival and viability, with higher DNA damage in β- than α-cells. These findings identified the weakness of β-cell antioxidant capacity as a main cause of vulnerability to oxidative stress. Potential strategies to enhance β-cell antioxidant capacity might be effective in prevention/treatment of diabetes.

Environmental enrichment reduces cocaine neurotoxicity during cocaine-conditioned place preference in male rats

Environmental enrichment (EE) has a neuroprotective role and prevents the development of cocaine addiction behavior in rats. Studies showing the role of EE in cocaine toxicity are nonexistent. We hypothesized that rats exposed to EE are protected from cocaine-induced changes in the redox profile and DNA damage after undergoing conditioned place preference (CPP). Ten male Wistar rats were placed in EE cages equipped with toys, a ladder and tunnels, and ten were provided clean, standard laboratory housing (non-EE). EE and non-EE rats were randomly allocated to the classical CPP cocaine vs. saline (COC/Saline) group, where cocaine (15 mg/kg; i.p.) was tested alternately with saline. Afterwards, intracellular reactive species and antioxidant enzymes were evaluated and the comet essay was performed in the prefrontal cortex and hippocampus of rats. As expected, EE rats spent less time in the cocaine-paired chamber, and as a new result, less cocaine-induced DNA damage was observed in the two brain structures. Altogether, our results demonstrate that EE decreases neurotoxicity in brain regions linked to cocaine addiction but does not extinguish it completely.

Spontaneous up-regulation of SIRT1 during osteogenesis contributes to stem cells' resistance to oxidative stress.

Osteogenic differentiation of bone marrow-derived mesenchymal stem cells (BM-MSCs) is a central event in bone formation. However, oxidative stress has a deleterious impact on BM-MSC osteogenesis. In this study, we hypothesized that oxidative stress influenced BM-MSC osteogenesis differently in the early or late stages, in which silent information regulator type 1 (SIRT1) played a critical role. A continuous exposure to sublethal concentrations of hydrogen peroxide (H2 O2 ), ranging from 25 to 100 µM for 21 days, resulted in the complete inhibition of BM-MSC osteogenesis. We found that a 7-day treatment with H2 O2 inhibited the lineage commitment of BM-MSCs toward osteoblasts, as evidenced by a significant reduction of alkaline phosphatase activity (a typical marker for early osteogenesis). However, moderate oxidative stress did not affect late-differentiated BM-MSCs, as there were comparable levels of matrix mineralization (a typical marker for late osteogenesis). In addition, we observed a spontaneous up-regulation of SIRT1 and intracellular antioxidant enzymes such as superoxide dismutase 2, catalase, and glutathione peroxidase 1, which accounted for the enhanced resistance to oxidative stress upon osteogenic differentiation. Activation of SIRT1 by resveratrol rescued the effect of H2 O2 on early-differentiated BM-MSCs and inhibition of SIRT1 by nicotinamide intensified the effect of H2 O2 on late-differentiated BM-MSCs, indicating that the SIRT1-mediated pathway was actively involved in MSC osteogenesis and antioxidant mechanisms. Our findings uncovered the relationship between SIRT1 and resistance to H2 O2 -induced oxidative stress during BM-MSC osteogenesis, which could provide a new strategy for protecting MSCs from extracellular oxidative stress.

Rapid Analysis and Guided Isolation of Astragalus Isoflavonoids by UHPLC-DAD-MSn and Their Cellular Antioxidant Defense on High-Glucose-Induced Mesangial Cell Dysfunction.

Isoflavonoids, including isoflavones, isoflavans, and pterocarpans, the principal components in Astragalus membranaceus, have a great deal of versatile health-promoting benefits. In this work, as a continuation of our search for bioactive constituents from A. membranaceus, a fast high-performance liquid chromatography-diode array detection-multiple-stage mass spectrometry method was first used to analyze the isoflavonoid profile of A. membranaceus roots extract. Twelve diverse isoflavonoids in subclasses of isoflavones, isoflavans, and pterocarpans present in glycoside/aglycone pair forms were tentatively characterized; of those 12, eight major isoflavonoids were finally isolated and simultaneously quantified by the established fast UHPLC method. Furthermore, the results confirmed for the first time that Astragalus isoflavonoid aglycones could attenuate mesangial cell proliferation and extracellular matrix (ECM) accumulation triggered by high glucose levels, and the primary mechanism might be via protecting intracellular antioxidant enzymes activities and enhancing endogenous antioxidant function to lower levels of cellular oxidative damage induced by high glucose levels. Collectively, diverse Astragalus isoflavonoid antioxidants have the potential to ameliorate high-glucose-induced mesangial cell dysfunction through the regulation of cellular antioxidant defense.

Cytoprotective effects of a tripeptide from Chinese Baijiu against AAPH-induced oxidative stress in HepG2 cells via Nrf2 signaling.

Antioxidant peptides have been widely reported, whereas the intracellular antioxidant activity of a tripeptide (Pro-His-Pro, PHP), which was newly isolated and identified from Chinese Baijiu in our previous study, are still poorly understood. This study investigated the protective effects of PHP on 2,2′-azobis (2-methyl-propanimidamidine) dihydrochloride (AAPH)-induced oxidative stress in HepG2 cells and the involved molecular mechanisms. Pretreatment with PHP suppressed the generations of reactive oxygen species (ROS), malondialdehyde (MDA) and oxidized glutathione (GSSG), prevented a decrease in reduced glutathione (GSH), and up-regulated the activities of cellular antioxidant enzymes. Moreover, PHP treatment stimulated the mRNA and protein expression levels of antioxidant enzymes and nuclear factor E2 related factor 2 (Nrf2). Meanwhile, PHP markedly reduced the level of Kelch-like ECH-associated protein 1 (Keap1), suggesting that PHP effectively activated Nrf2/antioxidant response element (ARE)-mediated activity. These findings provide the first molecular basis for the health-promoting effects of PHP to prevent AAPH-induced oxidative stress.

Effect of radiotherapy on activity and concentration of serum paraoxonase-1 in breast cancer patients.

Paraoxonase-1 (PON1) is an intra-cellular antioxidant enzyme found also in the circulation associated with high-density lipoproteins. The activity of this enzyme has been shown to be decreased in breast cancer (BC) patients. The aims of our study were to investigate the changes produced by radiotherapy (RT) on activity and concentration of serum PON1 in BC patients, and to evaluate the observed variations in relation to clinical and pathological characteristics of patients and tumors, and the response to treatment. We studied 200 women with BC who were scheduled to receive RT following excision of the tumor. Blood for analyses was obtained before and after the irradiation procedure. The control group was composed of 200 healthy women. Relative to control, BC patients had significantly lower serum PON1 activities pre-RT, while PON1 concentrations were at similar levels. RT was associated with a significant increase in serum PON1 activities and concentrations. We observed significant differences in serum PON1 concentrations post-RT between patients with luminal A or luminal B tumors. Serum PON1 concentration post-RT was markedly lower in BC patients with metastases. We conclude that benefit from RT accrues to the BC patients not only through its direct effect on cancer cells but also indirectly by improving the organism’s anti-oxidant defense mechanisms. In addition, our preliminary evidence suggests that the measurement of serum PON1 concentration post-RT could be an efficient prognostic biomarker, and may be used as an index of the efficacy of the RT.

P3.05-003 Serum Thioredoxin Reductase 1 as a Diagnostic Biomarker for Non-Small Cell Lung Cancer

Non-invasive diagnostic biomarkers for patients with suspicious non-small cell lung cancer (NSCLC) may provide needed guidance on invasive diagnostic and therapeutic decisions. Thioredoxin reductase 1 (TrxR1) is a pivotal intracellular redox sensor and antioxidant enzyme, and plays an important part in tumor growth, progression, metastasis, and chemotherapy resistance. The goal of this study is to test the feasibility of developing plasma TrxR1 as a novel diagnostic biomarker for NSCLC.

Hepatoprotective effects of raspberry (Rubus coreanus Miq.) seed oil and its major constituents

Raspberry seed is a massive byproduct of raspberry juice and wine but usually discarded. The present study employed a microwave-assisted method for extraction of raspberry seed oil (RSO). The results revealed that omega-6 fatty acids (linoleic acid and γ-linolenic acid) were the major constituents in RSO. Cellular antioxidant enzyme activity such as superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT) were investigated in HepG2 cells treated with RSO. Induction of the synthesis of several antioxidants in H2O2-exposed HepG2 cells was found. RSO increased the enzyme activity of SOD, CAT, and GPx in H2O2-exposed HepG2. Furthermore, RSO inhibited the phosphorylation of upstream mitogen-activated protein kinases (MAPK) such as c-Jun N-terminal kinase (c-JNK) and extracellular signal-regulated kinase (ERK). Taken together, the possible mechanisms to increase antioxidant enzyme activities in HepG2 may through the suppression of ERK and JNK phosphorylation. Raspberry seed oil exhibited good effects on the activities of the intracellular antioxidant enzymes and seems to protect the liver from oxidative stress through the inhibition of MAPKs.

Effect of serum antioxidant levels on sperm function in infertile male

Abstract Antioxidant and reactive oxygen species (ROS) has been implicated in male infertility. Antioxidants are compounds which scavenge formation or oppose of the actions ROS. Spermatozoa are particularly vulnerable to ROS because of inherent deficiencies in intracellular antioxidant enzyme protection, thus total body antioxidant capacity become more substantial to protect sperm. In this study to try to evaluate the role of serum total antioxidant capacity, uric acid, glutathione, total thiols, ferritin, albumin and malodialdehyde in male infertility. 66 men included in this study 40 were infertile and 26 were healthy fertile. Results showed a significant decrease in sperm progressive motility and a significant increase in sperm tail abnormality, also there were a significant decrease in serum total antioxidant capacity, uric acid and albumin in infertile group. Because of lack of the intracellular antioxidant enzymes sperm cannot protect plasma membrane that surrounds the tail, the protection depends on the antioxidant defense afforded by the seminal plasma and on the entire body antioxidant capacity. Decrease of serum antioxidant capacity, uric acid and albumin may cause destroy of sperm tail membrane and this may lowering of sperm progressive motility.

Abstract 4643: Plasma thioredoxin reductase 1 as a diagnostic marker for non-small cell lung cancer

Abstract Non-invasive diagnostic markers for patients with suspicious non-small cell lung cancer (NSCLC) may provide needed guidance on invasive diagnostic and therapeutic decisions. Thioredoxin reductase 1 (TrxR1) is a pivotal intracellular redox sensor and antioxidant enzyme, and plays an important part in tumor growth, progression, metastasis, and chemotherapy resistance. The goal of this study is to test the feasibility of developing plasma TrxR1 as a novel diagnostic marker for NSCLC. The plasma TrxR1 activity was determined spectrophotometrically by monitoring the NADPH-dependent production of 2-nitro-5-thiobenzoate at 412nm and at 37°C. All detection kits and automatic analyzer possess independent intellectual property rights, and have been widely used in breast cancer screening. In this study, the plasma levels of TrxR1 were measured in 45 treatment-naïve NSCLC patients and 10 individuals with benign tumor-like pulmonary diseases. Taking plasma TrxR1 activity of 4 as reference, the overall concordance rate was 73.3%, while those of CEA, CA199, CA125, NSE, CYFRA21-1 and SCC were 19.0%, 7.1%, 16.7%, 35.7%, 24.4% and 2.5%, respectively. Furthermore, using TNM staging (AJCC 7th ed.) as classifier, the concordance rates of TrxR1 in local, local regional and advanced stage subgroups were 66.7% (20/30), 77.8% (7/9) and 100% (4/4), respectively. A multipoint linear fitting correlation model was created, and the equation was TrxR1 = 5.821 + 0.396*Stage. Besides, the concordance rates of TrxR1 in benign tumor-like pulmonary diseases was 60% (6/10). Our data suggest that plasma TrxR1 activity is a useful non-invasive diagnostic marker for NSCLC, and there may be a linear correlation between TrxR1 activity and pathological stage. Citation Format: Xiaozheng Kang, Chaoran Dong, Bocun Shen, Wanpu Yan, Liang Dai, Yongbo Yang, Hanwei Yin, Guobing Xu, Huihui Zeng, Ke-Neng Chen. Plasma thioredoxin reductase 1 as a diagnostic marker for non-small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4643. doi:10.1158/1538-7445.AM2017-4643

Overexpression of glutathione peroxidase 1 predicts poor prognosis in oral squamous cell carcinoma.

Intracellular antioxidant enzymes are commonly upregulated in various cancer types and are associated with treatment outcomes. Because the relationship has rarely been examined in oral squamous cell carcinoma (OSCC), we aimed to evaluate the association between the levels of glutathione peroxidase (GPX)1, GPX4, and thioredoxin reductase (TrxR)1 expression and prognosis in patients with OSCC who underwent curative surgical resection. This study included 233 patients who underwent curative surgery for previously untreated OSCC between 2000 and 2012. Tumour GPX1, GPX4, and TrxR1 expression was evaluated by immunohistochemistry and was dichotomised to low and high values according to defined expression levels. The association between GPX1, GPX4, and TrxR1 expression and clinicopathological results was analysed. Univariate and multivariate analyses using the Cox proportional hazards model were conducted to assess the significance of differences in recurrence or survival outcomes between variables. High GPX1, GPX4, and TrxR1 expression was observed in 99 (42.5%), 133 (57.1%), and 46 (19.7%) patients, respectively. GPX1 overexpression was significantly correlated with nodal metastasis, advanced overall stage, depth of invasion of >10mm, high grade and perineural invasion (P<0.05). High GPX4 expression was also related to nodal metastasis, overall advanced stage and high grade (P<0.05). Univariate and multivariate analyses showed that increased GPX1 expression was significantly associated with poor disease-free, cancer-specific and overall survival (all P<0.05), while increased GPX4 or TrxR1 expression was not (all P>0.1). Tumour GPX1 expression is a useful biomarker predictive of recurrence and survival in OSCC patients.

P 016 - Cytoprotective effects of Chilean wild currants (Ribes spp.) against oxidative stress mediated by enhancing the activity of cellular antioxidant enzymes

The South American Ribes species are very appreciated for their sweet taste. Continuing our research on Ribes species, we decided to investigate the cytoprotective activity of this fruits against oxidative stress. Phenolic-enriched extracts (PEE), the anthocyanin fraction (AF) and copigments fraction (CF) were prepared in the lab. The cytoprotective effect of the Ribes was evaluated using human gastric epithelial cells (AGS). Cells were incubated overnight with the PEE, AF or CF at different concentrations. Then, AGS cells were exposed to H2O2 for 2 hour and viability was measured by means of the MTT reduction assay. In another experimental approach, cells were scrapped, collected by centrifugation and lysed to determine the activity of intracellular antioxidant enzymes. A significant cytoprotective effect was observed in a dose-dependent manner for all species studied. The highest activity was found for R. punctatum with 55.0 ± 1.8% of cell viability against 33.0 ± 0.4% of survival of untreated cells. No significant difference between PEE, AF or CF in the cytoprotective effect. A significant increase in the activity of superoxide dismutase by all Ribes species was found in a dose dependent manner. Our results on the protective potential of South American Ribes species provides evidence on the potential of native currants to be developed as functional foods.

Decreased paraoxonase 2 enzymatic activity in monocyte/macrophages cells. A comparative in vivo and in vitro study for diabetes

Aim: To investigate peripheral blood monocytes/macrophages (Mo/Mᴓ) paraoxonase 2 (PON2) in diabetes and the factors modulating its activity.Methods: One hundred and eighteen patients with newly diagnosed uncomplicated type 2 diabetes mellitus were compared regarding clinical, biochemical and oxidative stress parameters with 80 healthy subjects. The capacity of the peripheral blood mononuclear cells (PBMNC) to release pro-oxidants and to neutralise them was determined by measuring the respiratory burst (RB) and the intracellular antioxidant enzyme PON2. In vitro experiments were conducted on a differentiated monocytes cell line (dU937) that was exposed to serum deprivation followed by addition of isolated lipoproteins (VLDL or LDL).Results: Paraoxonase 2 activity in Mo/Mᴓ was significantly lower in type 2 diabetes patients (0.042 ± 0.044 vs 0.165 ± 0.133U lactonase activity/mg protein in controls, p < .0005) and decreased in the obese in all groups. It was inversely correlated to parameters of adiposity (BMI and Waist Circumference), of glucose control (blood glucose, fructosamine and HbA1c) and insulin resistance (HOMA-IR). In multivariate regression models, 15–34% of the PON2 variance was explained by diabetes. The in vitro addition of VLDL normalised the RB of serum deprived dU937 cells, S− (to 82 ± 18% of the cells incubated with serum, S+) and PON2 activity (from 0.524 ± 0.061 in S − to 0.298 ± 0.048 U/mg protein). In contrast, when LDL was added, the RB remained lower (61 ± 12% of S+, p = .03) and PON2 higher (0.580 ± 0.030 U/mg protein, p = .003).Conclusions: The decrease in monocyte/macrophage PON2 enzymatic activity observed in type 2 diabetes cannot be totally explained by abdominal obesity and insulin resistance. The underlying molecular mechanisms need to be identified.

Effects of pulsed electric field on intracellular antioxidant activity and antioxidant enzyme regulating capacities of pine nut (Pinus koraiensis) peptide QDHCH in HepG2 cells

Effects of pulse electric field (PEF) on antioxidant activity of pine nut (Pinus koraiensis) peptide were discussed using H2O2-induced HepG2 cells and changes of peptide structures were measured by MIR, NMR and CD spectra. Using HPLC-MS/MS, a novel peptide was identified as QDHCH. After PEF treatment the DPPH and ABTS radical inhibition, and CAA values of QDHCH were increased to 85.13%±0.17%, 95.45%±0.12%, and 4670.10μmol of quercetin equivalents/100g. The PEF-treated QDHCH has better protective oxidative stress inhibitory of 74.22±3.70%, and the T-SOD, CAT, GSH-Px and GSH-Rx activities in cells were significantly increased by 91.92, 7.98, 18.5 and 18.79U/mg prot, while the MDA content was decreased to 8.45±0.71U/mg prot compared with H2O2 damaged group. In addition, the hydroxyl radical scavenging activity of QDHCH was increased by 10.53%; the basic structure was not changed by PEF, while the influenced secondary structures may induce the antioxidant activity improvement in HepG2 cells.

Strawberry (cv. Romina) Methanolic Extract and Anthocyanin-Enriched Fraction Improve Lipid Profile and Antioxidant Status in HepG2 Cells.

Dyslipidemia and oxidation of low density lipoproteins (LDL) are recognized as critical factors in the development of atherosclerosis. Healthy dietary patterns, with abundant fruit and vegetable consumption, may prevent the onset of these risk factors due to the presence of phytochemical compounds. Strawberries are known for their high content of polyphenols; among them, flavonoids are the major constituents, and it is presumed that they are responsible for the biological activity of the fruit. Nevertheless, there are only a few studies that actually evaluate the effects of different fractions isolated from strawberries. In order to assess the effects of two different strawberry extracts (whole methanolic extract/anthocyanin-enriched fraction) on the lipid profile and antioxidant status in human hepatocellular carcinoma (HepG2) cells, the triglycerides and LDL-cholesterol content, lipid peroxidation, intracellular reactive oxygen species (ROS) content and antioxidant enzymes’ activity on cell lysates were determined. Results demonstrated that both strawberry extracts not only improved the lipid metabolism by decreasing triglycerides and LDL-cholesterol contents, but also improved the redox state of HepG2 cells by modulating thiobarbituric acid-reactive substances production, antioxidant enzyme activity and ROS generation. The observed effects were more pronounced for the anthocyanin-enriched fraction.

Serum thioredoxin reductase 1 as a diagnostic marker for non-small cell lung cancer.

e23069 Background: Non-invasive diagnostic markers for patients with suspicious non-small cell lung cancer (NSCLC) may provide needed guidance on invasive diagnostic and therapeutic decisions. Thioredoxin reductase 1 (TrxR1) is a pivotal intracellular redox sensor and antioxidant enzyme, and plays an important part in tumor growth, progression, metastasis, and chemotherapy resistance. The goal of this study is to test the feasibility of developing plasma TrxR1 as a novel diagnostic marker for NSCLC. Methods: The plasma TrxR1 activity was determined spectrophotometrically by monitoring the NADPH-dependent production of 2-nitro-5-thiobenzoate at 412nm and at 37℃. All detection kits and automatic analyzer possess independent intellectual property rights, and have been widely used in breast cancer screening. Results: In this study, the plasma levels of TrxR1 were measured in 109 treatment-naïve resectable NSCLC patients and 15 individuals with benign tumor-like pulmonary diseases. Taking plasma TrxR1 activity of 5.0 as reference, the overall concordance rate was 58.1%, while those of CEA, CA199, CA125, NSE, CYFRA21-1 and SCC were 19.2%, 8.2%, 2.1%, 45.9%, 25.3% and 9.5%, respectively. Furthermore, using TNM staging (AJCC 7th ed.) as classifier, the concordance rates of TrxR1 in benign tumor-like pulmonary diseases, local and regional stage NSCLC subgroups were 53.3% (8/15), 57.5% (46/80) and 63.0% (17/27), respectively. A multipoint linear fitting correlation model was created, and the equation was TrxR1 = 5.716 + 0.4898*Stage. Conclusions: Our data suggest that plasma TrxR1 activity is a useful non-invasive diagnostic marker for NSCLC, and there may be a linear correlation between TrxR1 activity and pathological stage.

Protective effects of lichen metabolites evernic and usnic acids against redox impairment-mediated cytotoxicity in central nervous system-like cells

Lichens species produce unique secondary metabolites that attract increasing pharmacological interest, including their redox modulatory activities. Current work evaluated for the first time the in vitro cytoprotective properties, based on the antioxidant activities, of the Parmeliaceae lichens Evernia prunastri and Usnea ghattensis and the mechanism of action of their major phenolic constituents: the evernic and usnic acids, respectively. In two models of central nervous system-like cells (U373-MG and SH-SY5Y cell lines), exogenous H2O2 induced oxidative stress-mediated cytotoxicity. We first assessed their radical scavenging capacities (ORAC and DPPH tests) and the phenolic content of the extracts. At the optimal concentrations, pretreatments with evernic acid displayed significant protection against H2O2-induced cytotoxic damage in both models. It reversed the alterations in oxidative stress markers (including ROS generation, glutathione system and lipid peroxidation levels) and cellular apoptosis (caspase-3 activity). Such effects were in part mediated by a notable enhancement of the expression of intracellular phase-II antioxidant enzymes; a plausible involvement of the Nrf2 cytoprotective pathway is suggested. Usnic acid exerted similar effects, to some extent more moderate. Results suggest that lichen polyketides evernic and usnic acids merit further research as promising antioxidant candidates in the therapy of oxidative stress-related diseases, including the neurodegenerative disorders.

Protective effect of surface layer proteins isolated from four Lactobacillus strains on hydrogen-peroxide-induced HT-29 cells oxidative stress

The objective of this study was to explore the antioxidant effect of the surface layer proteins (SLPs) and their mechanism. We investigated four SLPs which were extracted from L. casei zhang, L. rhamnosus, L. gasseri and L. acidophilus NCFM respectively using LiCl. The protective effect of SLPs on H2O2-induced HT-29 cells oxidative injury was investigated. As results, SLPs (100μg/mL) could significantly mitigate HT-29 cells cytotoxicity, improve the activities of total antioxidant capacity (T-AOC), catalase (CAT) and superoxide dismutase (SOD), decrease the contents of malondialdehyde (MDA) and lactate dehydrogenase (LDH), compared with H2O2-induced group (P<0.05). Furthermore, SLPs were also shown to attenuate the apoptosis rate (10.94–24.03%, P<0.01), suppress the elevation of intracellular reactive oxygen species (ROS) and calcium levels, restore mitochondrial membrane potential (MMP) and block the activation of apoptosis-related proteins of caspase-3 and caspase-9 (P<0.05). Considering all the parameters analyzed, we concluded that Lactobacillus SLPs play an essential role in the antioxidant capacity of HT-29 cells induced by H2O2, and the mechanism could be attributed to SLPs’ ability to enhance the activity of the intracellular antioxidant enzyme system, reduce ROS accumulation and to inhibit apoptosis by regulating mitochondrial pathway.

Intracellular antioxidant activities of selected cereal phenolic extracts and mechanisms underlying the protective effects of adlay phenolic extracts on H2O2-induced oxidative stress in human erythrocytes

The intracellular antioxidant activities of millet, rice, wheat, brown rice, oat, buckwheat, corn and adlay phenolic extracts were evaluated in an ex vivo erythrocytes system. Buckwheat, corn, and brown adlay free phenolic extracts could effectively attenuate H2O2-induced erythrocyte hemolysis. The protective effects and involved mechanisms of polished adlay, brown adlay and adlay bran phenolic extracts were studied further. The intracellular antioxidant activities of adlay phenolic extracts decreased in the following order: adlay bran>brown adlay>polished adlay. Adlay bran free phenolic extract possessed stronger intracellular antioxidant activity than chlorogenic acid, p-coumaric acid and ferulic acid. The free phenolic extracts were more effective than bound phenolic extracts to suppress hemolysis and plasma oxidation through inhibition of MDA equivalents, MetHb and ROS generation and to restore the activities of Na+K+-ATPase, Ca2+Mg2+-ATPase and intracellular antioxidant enzyme to normal levels. Adlay-rich diets could reduce the incidence of cancer, cardiovascular and neurodegenerative diseases.

Nitric oxide (NO)-mediated mitochondrial damage plays a critical role in T-2 toxin-induced apoptosis and growth hormone deficiency in rat anterior pituitary GH3 cells

T-2 toxin, a major compound of trichothecenes, induces cell apoptosis and growth hormone (GH) deficiency and causes considerable growth retardation in animals and human cells. However, the mechanism underlying its growth suppression still remains unclear. Recent studies have suggested that ROS induced cell apoptosis and animal feed intake reduction, but there are limited reports on the role of RNS in T-2 toxin-mediated mitochondrial damage, cell apoptosis and growth retardation. Herein, T-2 toxin-induced GH3 cell damage and apoptosis were tested by MTT assay, LDH leakage and flow cytometry, respectively. Intracellular NO and antioxidant enzyme activity, ΔΨm, morphometric changes of mitochondria, the caspase pathway, and inflammatory factors were investigated. Free radical scavengers NAC, SOD and NO scavenger haemoglobin were used to explore the role of oxidative stress and the relationship between NO production and caspase pathway. The results clearly revealed that T-2 toxin caused significant increases in NO generation, cell apoptosis, GH deficiency, increased iNOS activity, upregulation of inflammatory factors and caspase pathway, decreases in ΔΨm and morphosis damage. These data suggest that mitochondria are a primary target of T-2 toxin-induced NO, and NO is a key mediator of T-2 toxin-induced cell apoptosis and GH deficiency via the mitochondria-dependent pathway in cells.