Low concentration of GA activates a preconditioning response in HepG2 cells during oxidative stress—roles of Hsp90 and vimentin

Oxidative stress can be a significant cause of cell death and apoptosis. We performed studies in HepG2 cells to explore whether prior exposure to oxidative stress (“oxidative preconditioning”) and geldanamycin (GA) treatment can protect the cell from damage caused by subsequent oxidative insults. The cells were treated with 10 nM GA for 24 h before oxidative stress. Oxidative preconditioning was achieved by 2 h exposures to H₂O₂ (50 μM) separated by a 10-h recovery period in normal culture medium. Oxidative stress was induced by exposure to 500 μM H₂O₂ for 24 h. The effects of GA and oxidative preconditioning were investigated on the formation of Hsp90, vimentin, insoluble vimentin aggregates, and cleavage of vimentin in a cell culture model of oxidative stress. GA treatment leads to enhanced expression of Hsp90 and vimentin and to inhibition of vimentin protein aggregation. Similar results were obtained by oxidative preconditioning. It is confirmed that low concentrations of GA protected HepG2 cells from subsequent oxidative stress by increasing the levels of Hsp90 and by alleviating the extent of cell apoptosis induced by oxidative stress, which is similar to oxidative preconditioning. However, in contrast to preconditioning, GA treatment obviously changed binding activity of Hsp90 to vimentin cleavages. All the above indicated that low concentrations of GA treatment triggered cell protection from oxidative stress. Both the level of Hsp90 and its ability to bind with vimentin were changed by low concentrations of GA and might contribute to oxidative stress protection.     

In vitro cytoprotective activity of cyanidin 3-glucoside extracts from Haematocarpus validus pomace on streptozotocin induced oxidative damage in pancreatic β-cells

Cyanidin-3-glucoside (C3Ghv) compounds were purified and isolated from the anthocyanins extract of Haematocarpus validus. C3Ghv were studied for antioxidant and cytoprotective properties on pancreatic β-cells of rat insulinoma cells (RINm5F) against the oxidative stress induced by streptozotocin (STZ). The exposure of RINm5F cells to C3Ghv at concentration of 100 and 200 μg/mL for 24 h reduced 10% and 23% cell viability, respectively, as compared to control cells. The pre-treatment of RINm5F cells with C3Ghv (50 µg/mL) increased the cell viability by 29% as compared to control, on being treated with STZ (10 mM) for 24 h. The pre-treatment of RINm5F cells with C3Ghv (50 µg/mL) for 24 h followed by exposure to STZ (10 mM) for 1 h decreased the generation of reactive oxygen species (ROS) by 57%, generation of nitric oxide by 22.8%, generation of malondialdehyde (MDA) by 32%, the production of p-ERK ½ by 83%, p-JNK by 82.6%, p-MEK by 57%, and p-p38 MAPK by 64%. The C3Ghv treatment also decreased the ratio of apoptotic proteins Bax to Bcl-2 by 61%, and improved the M2 phase of cell cycle by 75% as compared to STZ treated cells. The overall results suggest that C3Ghv protects pancreatic β-cells against oxidative stress-induced apoptosis, thereby implicating the significant role of C3Ghv as an antidiabetic agent.     

Enhanced lipoxygenase activity is involved in the stress response but not in the harmful lipid peroxidation and cell death of short-term cadmium-treated barley root tip

Root growth inhibition and radial root swelling were the characteristic symptoms of barley root tips after the short-term exposure of roots to 15 and 30 μM Cd. Higher Cd concentrations caused extensive cell death and root growth arrest. Enhanced lipid peroxidation was observed as early as 1 h after the short-term treatment in a Cd concentration-dependent manner. In contrast to lipid peroxidation, the induction of lipoxygenase activity was detected only 3 h after the exposure of roots to 15 or 30 μM Cd. In addition, it was not observed in 60 μM Cd-treated root tips. The highest lipoxygenase activity was detected 6 h after 15 μM Cd treatment in the meristematic and elongation zone of root tip and was probably associated with the radial expansion of cells. Our results indicate that the upregulation of lipoxygenase is an important component of stress response in barley roots to toxic Cd. It is probably involved in the morphological stress response of root tips or/and in the alleviation of Cd-induced toxic alterations in plant cell membranes, but it is not responsible for the Cd-induced harmful lipid peroxidation and cell death.     

Nickel-induced Inhibition of Wheat Root Growth is Related to H2O2 Production, but not to Lipid Peroxidation

Effects of exogenous nickel (Ni: 10 and 200 μM) on growth, mitotic activity, Ni accumulation, H₂O₂ content and lipid peroxidation as well as the activities of various antioxidative enzymes, such as superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and glutathione peroxidase (GSH-Px) were investigated in wheat roots. A considerable Ni accumulation in the roots occurred at both the concentrations. Although Ni at 10 μM did not have any significant effect on root growth, it strongly inhibited the root growth at 200 μM. Mitotic activity in the root tips was not significantly affected by exposure of the seedlings to 10 μM Ni; however, it was almost completely inhibited at 200 μM treatment. Ni stress did not result in any significant changes in CAT and APX activities as well as lipid peroxidation. However, H₂O₂ concentration increased up to 82% over the control in the roots of seedlings exposed to 200 μM Ni. There was a significant decline in both SOD (50%) and GSH-Px (20–30%) activities in the roots when the seedlings were treated with 200 μM Ni. The results indicated that a strong inhibition of wheat root growth caused by Ni stress was not due to enhanced lipid peroxidation, but might be related to the accumulation of H₂O₂ in root tissue.     

Nicotine Deteriorates the Osteogenic Differentiation of Periodontal Ligament Stem Cells through α7 Nicotinic Acetylcholine Receptor Regulating wnt Pathway

Aims

Cigarette smoking is one of the high risk factors of adult chronic periodontitis and nicotine is the well established toxic substance in cigarette. However, the mechanism of nicotine induced periodontitis is still unknown. Here we studied whether nicotine impaired the osteogenic differentiation of human periodontal ligament stem cells (hPDLSCs) through activating α7 nicotinic acetylcholine receptor (α7 nAChR).

Methods

hPDLSCs with multi differentiation potential and surface makers for mesenchymal stem cells were harvested by limiting dilution technique. The level of mineralized nodule formation was assessed by alizarin red S staining. Expression level of ostegenic related genes and proteins were detected by real-time PCR and western blot analysis. The expression of α7 nAChR and its downstream signaling pathway were examined by western blot. The role of the receptor and related signaling pathway in nicotine impairing the osteogenic potential of hPDLSCs were also studied in different levels.

Results

Nicotine deteriorated the ostegenic differentiation of hPDLSCs in a dose dependent manner. Activation of α7 nAChR by nicotine treatment activated wnt/β-catenin signaling pathway, leading to osteogenic deficiency of hPDLSCs. Blockage of α7 nAChR and wnt pathway inhibitor treatment rescued nicotine induced osteogenic differentiation deficiency.

Conclusions

These data suggested that nicotine activated α7 nAChR expressed on PDLSCs and further activated wnt signaling downstream, thus deteriorating the osteogenic potential of PDLSCs. The impairment of osteogenic differentiation of PDLSCs by nicotine might lead to cigarette smoking related periodontitis.     

Catalytic antioxidant AEOL 10150 treatment ameliorates sulfur mustard analog 2-chloroethyl ethyl sulfide-associated cutaneous toxic effects

Our previous studies and other published reports on the chemical warfare agent sulfur mustard (SM) and its analog 2-chloroethyl ethyl sulfide (CEES) have indicated a role of oxidative stress in skin injuries caused by these vesicating agents. We examined the effects of the catalytic antioxidant AEOL 10150 in the attenuation of CEES-induced toxicity using our established skin injury models (skin epidermal cells and SKH-1 hairless mice) to validate the role of oxidative stress in the pathophysiology of mustard vesicating agents. Treatment of mouse epidermal JB6 and human HaCaT cells with AEOL 10150 (50 μM) 1 h post-CEES exposure resulted in significant (p < 0.05) reversal of CEES-induced decreases in both cell viability and DNA synthesis. Similarly, AEOL 10150 treatment 1 h after CEES exposure attenuated CEES-induced DNA damage in these cells. Similar AEOL 10150 treatments also caused significant (p < 0.05) reversal of CEES-induced decreases in cell viability in normal human epidermal keratinocytes. Cytoplasmic and mitochondrial reactive oxygen species measurements showed that AEOL 10150 treatment drastically ameliorated the CEES-induced oxidative stress in both JB6 and HaCaT cells. Based on AEOL 10150 pharmacokinetic studies in SKH-1 mouse skin, mice were treated with a topical formulation plus subcutaneous injection (5 mg/kg) of AEOL 10150 1 h after CEES (4 mg/mouse) exposure and every 4 h thereafter for 12 h. This AEOL 10150 treatment regimen resulted in over 50% (p < 0.05) reversal of CEES-induced skin bi-fold and epidermal thickness, myeloperoxidase activity, and DNA oxidation in mouse skin. Results from this study demonstrate the potential therapeutic efficacy of AEOL 10150 against CEES-mediated cutaneous lesions, supporting AEOL 10150 as a medical countermeasure against SM-induced skin injuries.     

Role of oxidative stress in vinorelbine-induced vascular endothelial cell injury

Vinorelbine (VNR), a vinca alkaloid anticancer drug, often causes vascular injury such as venous irritation, vascular pain, phlebitis, and necrotizing vasculitis. The purpose of this study was to identify the mechanisms that mediate the cell injury induced by VNR in porcine aorta endothelial cells (PAECs). PAECs were exposed to VNR for 10 min followed by further incubation in serum-free medium without VNR. The exposure to VNR (0.3–30 μM) decreased the cell viability concentration and time dependently. The incidence of apoptotic cells significantly increased at 12 h after transient exposure to VNR. At the same time, VNR increased the activity of caspases. Interestingly, VNR rapidly depleted intracellular glutathione (GSH) and increased intracellular reactive oxygen species (ROS) production. Moreover, VNR depolarized the mitochondrial membrane potential and decreased cellular ATP levels. These VNR-induced cell abnormalities were almost completely inhibited by GSH and N-acetylcysteine. On the other hand, l-buthionine-(S,R)-sulfoximine, a specific inhibitor of GSH synthesis, aggravated the VNR-induced loss of cell viability. These results clearly demonstrate that VNR induces oxidative stress by depleting intracellular GSH and increasing ROS production in PAECs, and oxidative stress plays an important role in the VNR-induced cell injury.     

Increased salinity stress tolerance of Nicotiana tabacum L. in vitro plants with the addition of xyloglucan oligosaccharides to the culture medium

Xyloglucan oligosaccharides (XGOs), derived from the hydrolysis of plant cell wall xyloglucan, are a novel class of biostimulants that exert positive effects on plant growth and morphology and can enhance plant stress tolerance. The aim of this study was to determine the influence of the application of exogenous Tamarindus indica L. cell wall-derived XGOs on Nicotiana tabacum L. tolerance to salt stress by evaluating morphology, physiological, and metabolic changes. N. tabacum plants were grown in agar-gelled media for 2 mo under salt stress with 100 mM of sodium chloride (NaCl) ± 0.1 μM XGOs. The germination percentage (GP), number of leaves (NL), foliar area (FA), primary root length (PRL), and density of lateral roots (DLR) were measured. In addition, unaffected 21-d-old N. tabacum plants were treated with a salt shock (100 mM NaCl) ± 0.1 μM XGOs. Proline, total chlorophyll, and total carbonyl levels, in addition to lipid peroxidation degree and activities of four enzymes related to oxidative stress, were quantified. The results indicated that XGOs significantly improved N. tabacum plants development after exposure to salt stress. XGOs caused a significant increase in NL and PRL, promoted lateral root formation, and produced an increase in proline and total chlorophyll contents, while reducing protein oxidation and lipid peroxidation. Although the XGOs modulated the activity of the enzymes analyzed, they were not statistically different from the salt control. It was concluded that XGOs may act as metabolic inducers that trigger the physiological responses that counteract the negative effects of oxidative stress under saline conditions.

     

Hypothermic preconditioning of endothelial cells attenuates cold-induced injury by a ferritin-dependent process

Hypothermia for myocardial protection or storage of vascular grafts may damage the endothelium and impair vascular function upon reperfusion/rewarming. Catalytic iron pools and oxidative stress are important mediators of cold-induced endothelial injury. Because endothelial cells are highly adaptive, we hypothesized that hypothermic preconditioning (HPC) protects cells at 0°C by a heme oxygenase-1 (HO-1) and ferritin-dependent mechanism. Storage of human coronary artery endothelial cells at 0°C caused the release of lactate dehydrogenase, increases in bleomycin-detectible iron (BDI), and increases in the ratio of oxidized/reduced glutathione, signifying oxidative stress. Hypoxia increased injury at 0°C but did not increase BDI or oxidative stress further. HPC at 25°C for 15–72 h attenuated these changes by an amount achievable by pretreating cells with 10–20 μM deferoxamine, an iron chelator, and protected cell viability. Treating cells with hemin chloride at 37°C transiently increased intracellular heme, HO-1, BDI, and ferritin. Elevated heme/iron sensitized cells to 0°C but ferritin was protective. HPC increased iron maximally after 2 h at 25°C and ferritin levels peaked after 15 h. HO-1 was not induced. When HPC-mediated increases in ferritin were blocked by deferoxamine, protection at 0°C was diminished. We conclude that HPC-mediated endothelial protection from hypothermic injury is an iron- and ferritin-dependent process.     

6 Iodo-δ-lactone: A derivative of arachidonic acid with antitumor effects in HT-29 colon cancer cells

BackgroundIL-δ (5-hydroxy-6 iodo-8,11,14-eicosatrienoic delta lactone) an iodinated arachidonic acid (AA) derivative, is one of the iodolipids biosynthesized by the thyroid. Although IL-δ regulates several thyroid parameters such as cell proliferation and goiter growth it was found that this iodolipid inhibits the growth of other non thyroid cell lines.ObjectivesTo study the effect of IL-δ on cell proliferation and apoptosis in the colon cancer cell line HT-29.ResultsTreatment with IL-δ reduced cell viability in a concentration-dependent manner: 1 μM 20%, 5 μM 25%, 10 μM 31%, 50 μM 47% and caused a significant decrease of PCNA expression (25%). IL-δ had pro-apoptotic effects, evidenced by morphological features of programmed cell death such as pyknosis, karyorrhexis, cell shrinkage and cell blebbing observed by fluorescence microscopy, and an increase in caspase-3 activity and in Bax/Bcl-2 ratio (2.5 after 3 h of treatment). Furthermore, IL-δ increased ROS production (30%) and lipid peroxidation levels (19%), suggesting that apoptosis could be a result of increased oxidative stress. A maximum increase in c-fos and c-jun protein expression in response to IL-δ was observed 1 h after initiation of the treatment. IL-δ also induced a tumour growth delay of 70% compared to the control group in NIH nude mice implanted with HT-29 cells.ConclusionOur study shows that IL-δ inhibits cell growth and induces apoptosis in the colon cancer cell line, HT-29 and opens the possibility that IL-δ could be a potential useful chemotherapy agent.     

Dexamethasone protects cultured rat hepatocytes against cadmium toxicity: involvement of cellular thiols

In the present study, the effects of dexamethasone on cadmium-induced toxicity were evaluated in isolated rat hepatocytes. Hepatocytes were cultured for 24 h in William’s E medium containing fetal calf serum (10%), insulin (0.1 IU/ml), and glucagon (0.01 μM) in the absence or presence of 0.1 μM dexamethasone. Cadmium chloride, 5 or 10 μM, was added to the medium and the toxicity was evaluated for up to 48 h after treatment. Lactate dehydrogenase (LDH) release, the reduced and oxidized glutathione ratio (GSH/GSSG), protein-SH groups, and lipid peroxidation levels were evaluated. Cadmium induced a dose- and time-dependent LDH release in control hepatocytes at 24 h (Cd 10 μM 42%) while hepatocytes pretreated with dexamethasone showed lower necrosis (Cd 10 μM 12% at 24 h). GSH/GSSH ratio and protein-SH groups were higher while lipid peroxidation was lower in dexamethasone-treated hepatocytes as compared with untreated cells. In conclusion, cadmium toxicity was associated with an increase in intracellular oxidative stress responsible for accelerated cell death. The use of dexamethasone prevented cadmium damage, suggesting that the cytoprotective action of this hormone is related to its effect in preventing changes in thiols such as glutathione and protein-SH groups.     

The triterpene,methyl-3β-hydroxylanosta-9,24-dien-21-oate (RA3), attenuates high glucose-induced oxidative damage and apoptosis by improving energy metabolism

BackgroundHyperglycemia-induced cardiovascular dysfunction has been linked to oxidative stress and accelerated apoptosis in the diabetic myocardium. While there is currently no treatment for diabetic cardiomyopathy (DCM), studies suggest that the combinational use of anti-hyperglycemic agents and triterpenes could be effective in alleviating DCM.HypothesisTo investigate the therapeutic effect of methyl-3β-hydroxylanosta-9,24-dien-21-oate (RA3), in the absence or presence of the anti-diabetic drug, metformin (MET), against hyperglycemia-induced cardiac injury using an in vitro H9c2 cell model.MethodsTo mimic a hyperglycemic state, H9c2 cells were exposed to high glucose (HG, 33 mM) for 24 h. Thereafter, the cells were treated with RA3 (1 μM), MET (1 μM) and the combination of MET (1 μM) plus RA3 (1 μM) for 24 h, to assess the treatments therapeutic effect.ResultsBiochemical analysis revealed that RA3, with or without MET, improves glucose uptake via insulin-dependent (IRS-1/PI3K/Akt signaling) and independent (AMPK) pathways whilst ameliorating the activity of antioxidant enzymes in the H9c2 cells. Mechanistically, RA3 was able to alleviate HG-stimulated oxidative stress through the inhibition of reactive oxygen species (ROS) and lipid peroxidation as well as the reduced expression of the PKC/NF-кB cascade through decreased intracellular lipid content. Subsequently, RA3 was able to mitigate HG-induced apoptosis by decreasing the activity of caspase 3/7 and DNA fragmentation in the cardiomyoblasts.ConclusionRA3, in the absence or presence of MET, demonstrated potent therapeutic properties against hyperglycemia-mediated cardiac damage and could be a suitable candidate in the prevention of DCM.     

Antioxidant additives reduce reactive oxygen species production in articular cartilage during exposure to cryoprotective agents

High concentrations of cryoprotective agents (CPA) are required during articular cartilage cryopreservation but these CPAs can be toxic to chondrocytes. Reactive oxygen species have been linked to cell death due to oxidative stress. Addition of antioxidants has shown beneficial effects on chondrocyte survival and functions after cryopreservation. The objectives of this study were to investigate (1) oxidative stress experienced by chondrocytes and (2) the effect of antioxidants on cellular reactive oxygen species production during articular cartilage exposure to high concentrations of CPAs. Porcine cartilage dowels were exposed to a multi-CPA solution supplemented with either 0.1 mg/mL chondroitin sulfate or 2000 μM ascorbic acid, at 4 °C for 180 min (N = 7). Reactive oxygen species production was measured with 5 μM dihydroethidium, a fluorescent probe that targets reactive oxygen species. The cell viability was quantified with a dual cell membrane integrity stain containing 6.25 μM Syto 13 + 9 μM propidium iodide using confocal microscopy. Supplementation of CPA solutions with chondroitin sulfate or ascorbic acid resulted in significantly lower dihydroethidium counts (p < 0.01), and a lower decrease in the percentage of viable cells (p < 0.01) compared to the CPA-treated group without additives. These results indicated that reactive oxygen species production is induced when articular cartilage is exposed to high CPA concentrations, and correlated with the amount of dead cells. Both chondroitin sulfate and ascorbic acid treatments significantly reduced reactive oxygen species production and improved chondrocyte viability when articular cartilage was exposed to high concentrations of CPAs.     

Oxidative Stress Induced by Cadmium in the C6 Cell Line: Role of Copper and Zinc

In this report, we have investigated the role of copper (Cu) and zinc (Zn) in oxidative stress induced by cadmium (Cd) in C6 cells. Cells were exposed to 20 μM Cd, 500 μM Cu, and 450 μM Zn for 24 h. Then, toxic effects, cellular metals levels, oxidative stress parameters, cell death, as well as DNA damage were evaluated. Cd induced an increase in cellular Cd, Cu, and Zn levels. This results not only in the inhibition of GSH-Px, GRase, CAT, and SOD activities but also in ROS overproduction, oxidative damage, and apoptotic cell death not related to Cu and Zn mechanisms. The thiol groups and GSH levels decreased, whereas the lipid peroxidation and DNA damage increased. The toxicity of Zn results from the imbalance between the inhibition of antioxidant activities and the induction of MT synthesis. The increase in Cu and Zn levels could be explained by the disruption of specific transporter activities, Cd interference with signaling pathways, and metal displacement. Our results suggest that the alteration of Cu and Zn homeostasis is involved in the oxidative stress induced by Cd.     

Superoxide-hydrogen peroxide imbalance differentially modulates the keratinocytes cell line (HaCaT) oxidative metabolism via Keap1-Nrf2 redox signaling pathway

The purpose of this study was to investigate the effect of a superoxide-hydrogen peroxide (S-HP) imbalance of the superoxide dismutase manganese dependent (SOD2) gene, generated by paraquat and porphyrin exposure, on the keratinocytes cell line (HaCaT) oxidative metabolism. Paraquat acts increasing superoxide (O^·?₂) levels, while porphyrin increases hydrogen peroxide (H₂O₂) levels, acting as VV-SOD2-like and AA-SOD2-like molecules, respectively. First of all, HaCAT cells were treated with different concentrations of paraquat and porphyrin (1; 10; 30, and 70 μM) to determine the concentration of both that causes imbalance. After defining the concentration of paraquat and porphyrin (70 μM), a time curve was performed (1, 3, 6, and 24 h) to evaluate ROS production levels. Other oxidative parameters, such as nitric oxide (NO), lipoperoxidation (TBARS) and protein carbonyl, were evaluated after 24 h of incubation, as well as genotoxic analyses, apoptosis detection, and gene expression. Our findings revealed that paraquat exposure decreased cell viability, increasing lipoperoxidation, DNA damage, and apoptosis. On the other hand, porphyrin treatment increased cell viability and proliferation, ROS and NO production, triggering protein and DNA damage. In addition, porphyrin up-regulated Keap1 and Nrf2 gene expression, while paraquat decreased Nrf2 gene expression. In this sense, we suggested that the superoxide-hydrogen peroxide imbalance differentially modulates oxidative stress on keratinocytes cell line via Keap1-Nrf2 gene expression pathway.

     

Analysis of cytotoxic effects of chlorhexidine gluconate as antiseptic agent on human blood lymphocytes

The aim of this study was to assess the cytotoxicity of chlorhexidine gluconate (CHG) on human blood lymphocytes as a useful ex vivo model for accelerated human toxicity studies. Using biochemical and flow cytometry assessments, we demonstrated that addition of CHG at 1 μM concentration to human blood lymphocytes induced cytotoxicity following 6 h. The CHG‐induced cytotoxicity on human blood lymphocytes was associated with intracellular reactive oxygen species generation, mitochondrial membrane potential collapse, lysosomal membrane injury, lipid peroxidation, and depletion of glutathione. According to our results, CHG triggers oxidative stress and organelles damages in lymphocytes which are important cells in defense against foreign agents. Finally our findings suggest that using of antioxidants and mitochondrial/lysosomal protective agents could be of benefit for the people in the exposure with CHG.     

Metformin does not prevent DNA damage in lymphocytes despite its antioxidant properties against cumene hydroperoxide-induced oxidative stress

Metformin (1-(diaminomethylidene)-3,3-dimethyl-guanidine), which is the most commonly prescribed oral antihyperglycaemic drug in the world, was reported to have several antioxidant properties such as the inhibition of advanced glycation end-products. In addition to its use in the treatment of diabetes, it has been suggested that metformin may be a promising anti-aging agent. The present work was aimed at assessing the possible protective effects of metformin against DNA-damage induction by oxidative stress in vitro. The effects of metformin were compared with those of N-acetylcysteine (NAC). For this purpose, peripheral blood lymphocytes from aged (n = 10) and young (n = 10) individuals were pre-incubated with various concentrations of metformin (10–50 μM), followed by incubation with 15 μM cumene hydroperoxide (CumOOH) for 48 h, under conditions of low oxidant level, which do not induce cell death. Protection against oxidative DNA damage was evaluated by use of the Comet assay and the cytokinesis-block micronucleus technique. Changes in the levels of malondialdehyde + 4-hydroxy-alkenals, an index of oxidative stress, were also measured in lymphocytes. At concentrations ranging from 10 μM to 50 μM, metformin did not protect the lymphocytes from DNA damage, while 50 μM NAC possessed an effective protective effect against CumOOH-induced DNA damage. Furthermore, NAC, but not metformin, inhibited DNA fragmentation induced by CumOOH. In contrast to the lack of protection against oxidative damage in lymphocyte cultures, metformin significantly protected the cells from lipid peroxidation in both age groups, although not as effective as NAC in preventing the peroxidative damage at the highest doses. Within the limitations of this study, the results indicate that pharmacological concentrations of metformin are unable to protect against DNA damage induced by a pro-oxidant stimulus in cultured human lymphocytes, despite its antioxidant properties.     

Genotoxicity and oxidative stress in fish after a short-term exposure to silver nanoparticles

This study examined the effects of waterborne silver nanoparticles (AgNPs) on juvenile fish Piaractus mesopotamicus (“pacú”), and analyzed toxicological endpoints such as metal burdens, oxidative stress and genotoxicity in a short-term assay. Fish were individually exposed to 0 (control), 2.5, 10, and 25 μg AgNPs/L. After 24 h, silver accumulation was greater in the brain than the liver and gills at all silver concentrations. Fish exposed to higher AgNPs concentrations showed major alterations in oxidative stress markers. An increase in lipid peroxidation (LPO) levels was observed in the liver of fish exposed to 10 μg AgNPs/L with no changes in the antioxidant enzymes activities. In the case of the 25 μg AgNPs/L treatment, a hepatic activation of the enzymatic antioxidant defense occurred, and LPO levels resulted unaltered. On the other hand, the brain presented the highest LPO levels at both 10 and 25 μg AgNPs/L exposures. The AgNPs toxicity was also evidenced by the DNA damage in fish erythrocytes at higher concentrations. Summarizing, a short exposure to sublethal concentrations of AgNPs is enough to generate deleterious effects on fish, including DNA damage.     

Epigallocatechin-3-gallate (EGCG) addition as an antioxidant in a cryo-diluent media improves microscopic parameters,and fertility potential,and alleviates oxidative stress parameters of buffalo spermatozoa

The disparity between the endogenous antioxidants concentration and free radicals in spermatozoa results in reactive oxygen species (ROS) generation. In this prospect, epigallocatechin-3-gallate (EGCG) preserves vigorous antioxidant features. Current study explored the influence of EGCG in a cryo-diluent media on microscopic parameters, oxidative stress parameters, and fertility potential of buffalo spermatozoa during cryopreservation. Concisely, collected semen from three donor bulls for four times were then evaluated for volume, motility, concentrations and then dilution in a cryo-diluent media with different concentrations of EGCG (EGCG-0 = control; EGCG-50 = 50 μM, EGCG-100 = 100 μM, EGCG-200 = 200 μM, and EGCG-300 = 300 μM) at 37 °C, cooled to 4 °C in 2 h, equilibrated for 4 h at 4 °C, and cryopreserved. At post-thawing, Computer-Assisted Sperm motion Analysis motilities (total and progressive, %) and rapid velocity (%), plasma membrane functionality, supravital plasma membrane integrity, and mitochondrial potential (%) were found higher (P < 0.05) in EGCG-200, and EGCG-300 than control, whereas average-path, straight-line, and curved-linear velocities (μm/sec), and acrosome integrity (%) were recorded higher in EGCG-300 than control. Further, comet length (μm), and tail length (μm), LPO (lipid peroxidation, μM/mL), and apoptosis-like changes (%) in spermatozoa were significantly decreased in EGCG-300 than control. Seminal plasma antioxidant enzymes activities (glutathione peroxidase, U/mL, and superoxide dismutase, U/mL) were increased with EGCG-300 than control. Moreover, EGCG-300 addition in a cryo-diluent media improves the fertility potential (%) of buffalo spermatozoa. In a nutshell, the inclusion of EGCG-300 in a cryo-diluent media enhances post-thaw microscopic parameters, and fertility potential, whereas decreases oxidative stress parameters in buffalo spermatozoa.