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Concept: Lipid peroxidation

169

BACKGROUND: The aim of this study was to screen various solvent extracts of whole plant of Torilis leptophylla to display potent antioxidant activity in vitro and in vivo, total phenolic and flavonoid contents in order to find possible sources for future novel antioxidants in food and pharmaceutical formulations. MATERIAL AND METHODS: A detailed study was performed on the antioxidant activity of the methanol extract of whole plant of Torilis leptophylla (TLM) and its derived fractions {n-hexane (TLH), chloroform (TLC) ethyl acetate (TLE) n-butanol (TLB) and residual aqueous fraction (TLA)} by in vitro chemical analyses and carbon tetrachloride (CCl4) induced hepatic injuries (lipid peroxidation and glutathione contents) in male Sprague-Dawley rat. The total yield, total phenolic (TPC) and total flavonoid contents (TFC) of all the fractions were also determined. TLM was also subjected to preliminary phytochemical screening test for various constituents. RESULTS: The total phenolic contents (TPC) (121.9+/-3.1 mg GAE/g extract) of TLM while total flavonoid contents (TFC) of TLE (60.9 +/-2.2 mg RTE/g extract) were found significantly higher as compared to other solvent fractions. Phytochemical screening of TLM revealed the presence of alkaloids, anthraquinones, cardiac glycosides, coumarins, flavonoids, saponins, phlobatannins, tannins and terpenoids. The EC50 values based on the DPPH (41.0+/-1 mug/ml), ABTS (10.0+/-0.9 mug/ml) and phosphomolybdate (10.7+/-2 mug/ml) for TLB, hydroxyl radicals (8.0+/-1 mug/ml) for TLC, superoxide radicals (57.0+/-0.3 mug/ml) for TLM and hydrogen peroxide radicals (68.0+/-2 mug/ml) for TLE were generally lower showing potential antioxidant properties. A significant but marginal positive correlation was found between TPC and EC50 values for DPPH, hydroxyl, phosphomolybdate and ABTS, whereas another weak and positive correlation was determined between TFC and EC50 values for superoxide anion and hydroxyl radicals. Results of in vivo experiment revealed that administration of CCl4 caused a significant increase in lipid peroxidation (TBARS) while decrease in GSH contents of liver. In contrast, TLM (200 mg/kg bw) and silymarin (50 mg/kg bw) co-treatment effectively prevented these alterations and maintained the antioxidant status. CONCLUSION: Data from present results revealed that Torilis leptophylla act as an antioxidant agent due to its free radical scavenging and cytoprotective activity.

Concepts: Oxygen, Reactive oxygen species, Flavonoid, Methane, Lipid peroxidation, Hydroxyl radical, Chloroform, Antioxidant

29

The aim of this study is to verify the evolution and involution of experimental atherosclerosis in rabbits through the study of endothelial function, lipids and tissue lipid peroxidation, macro and microscopic quantification of aortic atherosclerosis.

Concepts: Lipid peroxidation, Endothelial dysfunction, Lipid, Archaea, Sociology, Metabolism, Endothelium, Antioxidant

26

Frequency Mixing Magnetic Detection (FMMD) was used to detect superoxide from hypoxanthine and xanthine reaction, and hydroxylradical from Fenton reaction. FMMD was also applied to measure the reactive oxygen species (ROS) level released from microglial cells. We could assess the formation and extinction of the free radicals without a spin trap reagent. The FMMD signal amplitude scaled with the concentration of the radicals. It was verified that no signals are obtained from the substrates and reagents. Based on the observations and on previous research, we suggest that the FMMD signals originate from superoxide and hydroxyl radicals, suggesting that FMMD can be used to detect O-centered radicals. Subsequent analysis of free radicals generated from living microglial cells showed that there were significant differences between the activated microglial cells and resting ones. The results of this research are promising regarding the applications of FMMD for in in-situ measurement of free radicals from various sources including the cell.

Concepts: Lipid peroxidation, In situ, Mitochondrion, Reactive oxygen species, Fenton's reagent, Hydrogen peroxide, Oxidative stress, Hydroxyl radical

25

To analyse the trend in lipid peroxidation and antioxidant response as key markers of oxidative stress after paediatric cardiovascular surgery, and compare them with other internationally accepted clinical prognostic indicators.

Concepts: Medicine, Lipid peroxidation, Cardiothoracic surgery, Vitamin E, Oxidative phosphorylation, Reactive oxygen species, Oxidative stress, Antioxidant

25

While oxidative damage owing to reactive oxygen species (ROS) often increases with advancing age and is associated with many age-related diseases, its causative role in ageing is controversial. In particular, studies that have attempted to modulate ROS-induced damage, either upwards or downwards, using antioxidant or genetic approaches, generally do not show a predictable effect on lifespan. Here, we investigated whether dietary supplementation with either vitamin E (α-tocopherol) or vitamin C (ascorbic acid) affected oxidative damage and lifespan in short-tailed field voles, Microtus agrestis. We predicted that antioxidant supplementation would reduce ROS-induced oxidative damage and increase lifespan relative to unsupplemented controls. Antioxidant supplementation for nine months reduced hepatic lipid peroxidation, but DNA oxidative damage to hepatocytes and lymphocytes was unaffected. Surprisingly, antioxidant supplementation significantly shortened lifespan in voles maintained under both cold (7 ± 2°C) and warm (22 ± 2°C) conditions. These data further question the predictions of free-radical theory of ageing and critically, given our previous research in mice, indicate that similar levels of antioxidants can induce widely different interspecific effects on lifespan.

Concepts: Free-radical theory, Lipid peroxidation, Oxidative phosphorylation, Ascorbic acid, Oxidative stress, Vitamin C, Reactive oxygen species, Antioxidant

6

Enigmatic lipid peroxidation products have been claimed as the proximate executioners of ferroptosis-a specialized death program triggered by insufficiency of glutathione peroxidase 4 (GPX4). Using quantitative redox lipidomics, reverse genetics, bioinformatics and systems biology, we discovered that ferroptosis involves a highly organized oxygenation center, wherein oxidation in endoplasmic-reticulum-associated compartments occurs on only one class of phospholipids (phosphatidylethanolamines (PEs)) and is specific toward two fatty acyls-arachidonoyl (AA) and adrenoyl (AdA). Suppression of AA or AdA esterification into PE by genetic or pharmacological inhibition of acyl-CoA synthase 4 (ACSL4) acts as a specific antiferroptotic rescue pathway. Lipoxygenase (LOX) generates doubly and triply-oxygenated (15-hydroperoxy)-diacylated PE species, which act as death signals, and tocopherols and tocotrienols (vitamin E) suppress LOX and protect against ferroptosis, suggesting a homeostatic physiological role for vitamin E. This oxidative PE death pathway may also represent a target for drug discovery.

Concepts: Oxidizing agent, Lipid peroxidation, Glutathione peroxidase, Hydrogen, Redox, Vitamin E, Vitamin C, Antioxidant

5

In plants, hydrogen gas (H2) enhances tolerance to several abiotic stresses, including salinity and heavy metals. However, the effect of H2 on fungal growth under different stresses remains largely unclear. In this study, hydrogen-rich water (HRW) was employed to characterize physiological roles and molecular mechanisms of H2 in the alleviation of three different stresses in basidiomycete Hypsizygus marmoreus. Our results showed that HRW treatment, of which the H2 concentration was 0.8 mM, significantly reduced the toxicities of CdCl2, NaCl and H2O2, leading to significantly improved mycelial growth and biomass. These beneficial effects could be attributed to a significantly decreased formation of malondialdehyde (MDA). Besides, HRW treatment significantly increased the activities of antioxidants (SOD, CAT and GR) as well as the gene expressions of these antioxidants (SOD, CAT, and GR) at the mRNA level. In vivo detection of reactive oxygen species (ROS), including H2O2 and O2(-), as well as lipid peroxidation provided further evidence that HRW could significantly improve tolerances of CdCl2, NaCl and H2O2. Furthermore, pyruvate kinase was activated in the mycelia treated with HRW, along with its induced gene expression, suggesting that HRW treatment enhanced the glucose metabolism. Taken together, our findings suggested that the usage of HRW could be an effective approach for contaminant detoxification in H. marmoreus, which was similar with the effects of HRW in plants, and such effects could be also beneficial in entire agricultural system.

Concepts: Bacteria, Lipid peroxidation, Mycelium, Oxidative stress, Gene expression, Antioxidant, Oxygen, Reactive oxygen species

4

The selenoenzyme glutathione peroxidase 4 (Gpx4) is a major scavenger of phospholipid hydroperoxides. Although Gpx4 represents a key component of the reactive oxygen species-scavenging network, its relevance in the immune system is yet to be defined. Here, we investigated the importance of Gpx4 for physiological T cell responses by using T cell-specific Gpx4-deficient mice. Our results revealed that, despite normal thymic T cell development, CD8(+) T cells from T(ΔGpx4/ΔGpx4) mice had an intrinsic defect in maintaining homeostatic balance in the periphery. Moreover, both antigen-specific CD8(+) and CD4(+) T cells lacking Gpx4 failed to expand and to protect from acute lymphocytic choriomeningitis virus and Leishmania major parasite infections, which were rescued with diet supplementation of high dosage of vitamin E. Notably, depletion of the Gpx4 gene in the memory phase of viral infection did not affect T cell recall responses upon secondary infection. Ex vivo, Gpx4-deficient T cells rapidly accumulated membrane lipid peroxides and concomitantly underwent cell death driven by ferroptosis but not necroptosis. These studies unveil an essential role of Gpx4 for T cell immunity.

Concepts: Lipid peroxidation, Humoral immunity, Cell membrane, Infection, Thymus, Bacteria, Antioxidant, Immune system

4

Glutathione peroxidase 4(Gpx4), an antioxidant defense enzyme in repairing oxidative damage to lipids, is a key inhibitor of ferroptosis, a non-apoptotic form of cell death involving lipid reactive oxygen species. Here we show that Gpx4 is essential for motor neuron health and survival in vivo. Conditional ablation of Gpx4 in neurons of adult mice resulted in rapid onset and progression of paralysis, and death. Pathological inspection revealed that the paralyzed mice had a dramatic degeneration of motor neurons in spinal cord, but had no overt neuron degeneration in cerebral cortex. Consistent with Gpx4’s role as a ferroptosis inhibitor, spinal motor neuron degeneration induced by Gpx4 ablation exhibited features of ferroptosis including no caspase-3 activation, no TUNEL staining, activation of ERKs, and elevated spinal inflammation. Supplement of vitamin E, another inhibitor of ferroptosis, delayed the onset of paralysis and death induced by Gpx4 ablation. And lipid peroxidation and mitochondrial dysfunction appeared to be involved in ferroptosis of motor neurons induced by Gpx4 ablation. Taken together, the dramatic motor neuron degeneration and paralysis induced by Gpx4 ablation suggest that ferroptosis inhibition by Gpx4 is essential for motor neuron health and survival in vivo.

Concepts: Lipid peroxidation, Motor neuron, Oxidative stress, Glutathione, Oxidative phosphorylation, Reactive oxygen species, Spinal cord, Antioxidant

4

The purpose of this study was to investigate the potentially beneficial effects of apple cider vinegar (ACV) supplementation on serum triglycerides, total cholesterol, liver and kidney membrane lipid peroxidation, and antioxidant levels in ovariectomized (OVX) mice fed high cholesterol. Four groups of ten female mice were treated as follows: Group I received no treatment and was used as control. Group II was OVX mice. Group III received ACV intragastrically (0.6 % of feed), and group IV was OVX and was treated with ACV as described for group III. The treatment was continued for 28 days, during which the mice were fed a high-cholesterol diet. The lipid peroxidation levels in erythrocyte, liver and kidney, triglycerides, total, and VLDL cholesterol levels in serum were higher in the OVX group than in groups III and IV. The levels of vitamin E in liver, the kidney and erythrocyte glutathione peroxidase (GSH-Px), and erythrocyte-reduced glutathione (GSH) were decreased in group II. The GSH-Px, vitamin C, E, and β-carotene, and the erythrocyte GSH and GSH-Px values were higher in kidney of groups III and IV, but in liver the vitamin E and β-carotene concentrations were decreased. In conclusion, ACV induced a protective effect against erythrocyte, kidney, and liver oxidative injury, and lowered the serum lipid levels in mice fed high cholesterol, suggesting that it possesses oxidative stress scavenging effects, inhibits lipid peroxidation, and increases the levels of antioxidant enzymes and vitamin.

Concepts: Vitamin C, Cider, Apple, Reactive oxygen species, Lipid peroxidation, Cholesterol, Glutathione, Antioxidant