Glutathione peroxidase and glutathione reductase activities towards glutathione-derived antioxidants

Invitro impact of a combination of red and infrared LEDs, infrared laser and magnetic field on biomarkers of oxidative stress and hemolysis of erythrocytes sampled from healthy individuals and diabetes patients

AIMS

Low-intensity infrared laser irradiation with output emissions of the laser and LED for in vitro irradiation of plasma and erythrocyte samples collected from healthy individuals and diabetes mellitus (DM) patients was used in the current study.

METHODS

The generated emission was in the range 0.85-0.89 nm with pulse duration near 130 ns and repetition rates of pulses 50, 150, 600, and 1500 Hz, average power 0, 50, or 100 mW, in the range of 1-9 min for different 30 variants of irradiation. The levels of 2-thiobarbituric-acid reactive substances (TBARS), aldehydic and ketonic derivatives of oxidatively modified proteins (OMP), total antioxidant capacity (TAC), acid-induced resistance of erythrocytes, and activities of the main antioxidant enzymes were assessed in erythrocyte and plasma samples after irradiation.

RESULTS

The low-intensity infrared laser irradiation and low-intensity light emitted by a red LED decreased the lipid peroxidation levels in the erythrocytes of both healthy individuals and DM patients. A statistically significant decrease in TBARS and OMP levels and an increase in the TAC level were observed at the irradiation energy of 34.39 and 68.79 J/cm² for samples collected from both healthy individuals and DM patients. The effects of the irradiation were accompanied by a statistically significant decrease in catalase activity of both healthy individuals and DM patients.

CONCLUSIONS

In many variants of the laser irradiation and low-intensity light emitted by a red LED used in our study, a decrease in the percent of hemolyzed erythrocytes was observed, suggesting that laser therapy protocols should take into account fluencies, frequencies, and wavelengths of the laser before the beginning of treatment, especially in DM patients.

Cyclophilin A Cpr1 Protein Modulates the Response of Antioxidant Molecules to Menadione-induced Oxidative Stress in Saccharomyces cerevisiae KNU5377Y

Objectives

Methods

Results

Conclusion

Characterization of UPF peptides, members of the glutathione analogues library, on the basis of their effects on oxidative stress-related enzymes

Previously the authors have designed and synthesized a library of antioxidative glutathione analogues called UPF peptides which are superior to glutathione in hydroxyl radical elimination. This paper is a follow-up study which investigated the effects of the most promising members of the library (UPF1 and UPF17) on oxidative stress-related enzymes. At concentrations used in vivo experiments neither UPF peptide influenced the activity of glutathione peroxidase (GPx) when purified enzyme or erythrocyte lysate was used. At higher concentrations they inhibited GPx activity. UPF peptides had no effect on glutathione reductase (GR) activity. Also they, as well as glutathione itself, slightly increased MnSOD activity in human brain mitochondria and inhibited oxidative burst caused by neutrophil NAD(P)H oxidase. RT-PCR measurements showed that UPF1 and UPF17 have no effect on GPx and MnSOD expression level in human blood mononuclear cells. The results of this study confirm that investigated UPF peptides do not interfere with the enzymatic mechanisms of antioxidative defence and can be used as themselves or as a lead for the protector molecule design against excessive oxidative stress.

Design, synthesis and properties of novel powerful antioxidants, glutathione analogues

Glutathione (GSH) is the major low-molecular weight antioxidant in mammalian cells. Thus, its analogues carrying similar and/or additional positive properties might have clinical perspectives. Here, we report the design and synthesis of a library of tetrapeptidic GSH analogues called UPF peptides. Compared to cellular GSH our designed peptidic analogues showed remarkably higher hydroxyl radical scavenging ability (EC(50) of GSH: 1,231.0 +/- 311.8 microM; EC(50) of UPF peptides: from 0.03 to 35 microM) and improved antiradical efficiency towards a stable alpha,alpha-diphenyl-beta-picrylhydrazyl (DPPH) radical. The best of UPF peptides was 370-fold effective hydroxyl radical scavengers than melatonin (EC(50): 11.4 +/- 1.0 microM). We also found that UPF peptides do not influence the viability and membrane integrity of K562 human erythroleukemia cells even at 200 microM concentration. Dimerization of GSH and UPF peptides was compared in water and in 0.9% saline solutions. The results, together with an earlier finding that UPF1 showed protective effects in global cerebral ischemia model in rats, suggest that UPF peptides might serve both as potent antioxidants as well as leads for design of powerful non-peptidic antioxidants that correct oxidative stress-driven events.

N-acetylcysteine amide, a novel cell-permeating thiol, restores cellular glutathione and protects human red blood cells from oxidative stress

Oxidative stress plays an important role in the progression of neurodegenerative and age-related diseases, causing damage to proteins, DNA, and lipids. A novel thiol N-acetylcysteine amide (AD4), the amide form of N-acetylcysteine (NAC) and a Cu(2+) chelator, was assessed for its antioxidant and protective effects using human red blood cells (RBCs) as a model. AD4 was shown by flow cytometry to inhibit tert.-butylhydroxyperoxide (BuOOH)-induced intracellular oxidation in RBCs stained with the oxidant-sensitive probe 2',7'-dichlorofluorescein diacetate. In addition, AD4 retarded BuOOH-induced thiol depletion and hemoglobin oxidation. Restoration of the thiol-depleted RBCs by externally applied AD4 was significantly greater compared with NAC and, unlike NAC, was accompanied by hemoglobin protection from oxidation. In a cell-free system we have demonstrated that AD4 reacted with oxidized glutathione (GSSG) to generate reduced glutathione (GSH). The formation of GSH was determined enzymatically using GSH peroxidase and by HPLC. Based on these results a thiol-disulfide exchange between AD4 and GSSG is proposed as the mechanism underlying the antioxidant effects of AD4 on BuOOH-treated RBCs. Together, these studies demonstrate that AD4 readily crosses cell membranes, replenishes intracellular GSH, and, by incorporating into the redox machinery, defends the cell from oxidation. These results provide further evidence for the efficient membrane permeation of AD4 over NAC, and support the possibility that it could be explored for treatment of neurodegeneration and other oxidation-mediated disorders.

Design and synthesis of glutathione analogues

This review reports recent structural modifications (since 1989) performed on the glutathione molecular both in the oxidized and reduced form. Relevant chemical aspects, biochemical consequences and therapeutical implications are illustrated. Natural thiols related to glutathione are also considered.

Targeted lung expression of interleukin-11 enhances murine tolerance of 100% oxygen and diminishes hyperoxia-induced DNA fragmentation

Acute lung injury is a frequent and treatment-limiting consequence of therapy with hyperoxic gas mixtures. To determine if IL-11 is protective in oxygen toxicity, we compared the effects of 100% O2 on transgenic mice that overexpress IL-11 in the lung and transgene (-) controls. IL-11 markedly enhanced survival in 100% O2 with 100% of transgene (-) animals dying within 72-96 h and > 90% of transgene (+) animals surviving for more than 10 d. This protection was associated with markedly diminished alveolar-capillary protein leak, endothelial and epithelial membrane injury, lipid peroxidation, and pulmonary neutrophil recruitment. Significant differences in copper zinc superoxide dismutase and catalase activities were not noted and the levels of total, reduced and oxidized glutathione were similar in transgene (+) and (-) animals. Glutathione reductase, glutathione peroxidase, and manganese superoxide dismutase activities were slightly higher in transgene (+) as versus (-) mice after 100% O2 exposure, and IL-11 diminished hyperoxia-induced expression of IL-1 and TNF. Hyperoxia also caused cell death with DNA fragmentation in the lungs of transgene (-) animals and IL-11 markedly diminished this cell death response. These studies demonstrate that IL-11 markedly diminishes hyperoxic lung injury. They also demonstrate this protection is associated with small changes in lung antioxidants, diminished hyperoxia-induced IL-1 and TNF production, and markedly suppressed hyperoxia-induced DNA fragmentation.

N-conjugates of 2,5-disubstituted pyrrole and glutathione. Evaluation of their potency as antioxidants against photosensitization of NCTC 2544 keratinocytes by excess endogenous protoporphyrin IX

A novel glutathione compound in which the amino group has been derivatized by a 2,5-dimethyl pyrrole is shown to be very effective against cell photosensitization in vitro. Protoporphyrin IX either added to the medium or produced endogenously by incubation of NCTC 2544 keratinocytes with 5-aminolevulinic acid has been chosen as the photosensitizer. The antioxidant effectiveness of glutathione-pyrrole derivatives against protoporphyrin photosensitization depends critically on the type of 2,5 substitution on the pyrrole ring. This structure-function relationship may be attributed to the difference in compartmentation and/or uptake of the various glutathione-pyrrole derivatives under study. The 2,5-dimethyl pyrrole derivative is much more effective than glutathione as a protective agent against phototoxic reactions induced by protoporphyrin IX.