Effect of zinc nutritional status on activities of superoxide radical and hydrogen peroxide scavenging enzymes in bean leaves

1993 ◽  
Vol 155-156 (1) ◽  
pp. 127-130 ◽  
Author(s):  
I. Cakmak ◽  
H. Marschner
Keyword(s):  
Hydrogen Peroxide ◽  
Nutritional Status ◽  
Superoxide Radical ◽  
Scavenging Enzymes ◽  
Bean Leaves

Hydrogen peroxide is the most toxic oxygen species for Onchocerca cervicalis microfilariae

Parasitology ◽  
1990 ◽  
Vol 100 (3) ◽  
pp. 407-415 ◽  
Author(s):  
H. L. Callahan ◽  
R. K. Chouch ◽  
E. R. James
Keyword(s):  
Hydrogen Peroxide ◽  
Hydroxyl Radical ◽  
Singlet Oxygen ◽  
Superoxide Radical ◽  
Active Oxygen Species ◽  
Active Oxygen ◽  
Oxygen Species ◽  
Low Levels ◽  
Scavenging Enzymes

SUMMARYThe toxicity of the active oxygen species hydrogen peroxide, superoxide radical, hydroxyl radical and singlet oxygen to microfilariae (mf) has been studied in vitro, using active oxygen-generating systems and scavengers/inhibitors. Mf viability was monitored by uptake of the radiolabel, [3H]2-deoxy-D-glouse. Hydrogen peroxide and singlet oxygen, but not superoxide radical or hydroxyl radical, are toxic for mf. Hydrogen peroxide was toxic for mf within 2 h at concentrations as low as 5 ¼, an amount eosinophils have been shown to release in vitro (Weiss et al. 1986). Catalase and thiourea, but not inactivated catalase, superoxide dismutase (SOD), singlet oxygen scavengers, or hydroxyl radical scavengers, protected mf. Mf have relatively high levels of endogenous SOD but no measurable glutathione peroxidase and low levels of catalase when compared with other parasites (Callahan, Crouch & James, 1988). The low levels of hydrogen peroxide-scavenging enzymes correlate well with mf sensitivity to hydrogen peroxide and the protective effect of exogenous catalase.

An ESR study of the peroxidase reaction catalyzed by human methaemoglobin and methaemoglobin-haptoglobin complex

1991 ◽  
Vol 56 (4) ◽  
pp. 923-932
Author(s):  
Jana Stejskalová ◽  
Pavel Stopka ◽  
Zdeněk Pavlíček
Keyword(s):  
Hydrogen Peroxide ◽  
Ascorbic Acid ◽  
Amino Acid ◽  
Peroxidase Activity ◽  
Amino Acid Analysis ◽  
Superoxide Radical ◽  
Esr Spectra ◽  
The Other ◽  
Delocalized Electron

The ESR spectra of peroxidase systems of methaemoglobin-ascorbic acid-hydrogen peroxide and methaemoglobin-haptoglobin complex-ascorbic acid-hydrogen peroxide have been measured in the acetate buffer of pH 4.5. For the system with methaemoglobin an asymmetrical signal with g ~ 2 has been observed which is interpreted as the perpendicular region of anisotropic spectrum of superoxide radical. On the other hand, for the system with methaemoglobin-haptoglobin complex the observed signal with g ~ 2 is symmetrical and is interpreted as a signal of delocalized electron. After realization of three repeatedly induced peroxidase processes the ESR signal of the perpendicular part of anisotropic spectrum of superoxide radical is distinctly diminished, whereas the signal of delocalized electron remains practically unchanged. An amino acid analysis of methaemoglobin along with results of the ESR measurements make it possible to derive a hypothesis about the role of haptoglobin in increasing of the peroxidase activity of methaemoglobin.

Mechanisms involved in the protective effect of estradiol-17β on lipid peroxidation and DNA damage

1998 ◽  
Vol 274 (6) ◽  
pp. E1002-E1008 ◽  
Author(s):  
Stacey Ayres ◽  
William Abplanalp ◽  
James H. Liu ◽  
M. T. Ravi Subbiah
Keyword(s):  
Hydrogen Peroxide ◽  
Lipid Peroxidation ◽  
Dna Damage ◽  
Superoxide Radical ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Chain Propagation ◽  
Similar Degree ◽  
Estradiol 17Β ◽  
Ros Scavengers

Previous studies from our laboratory have shown that estrogens can protect against lipoprotein peroxidation and DNA damage. In this study, the mechanism of estradiol-17β (E2) action was investigated by comparing E2 with selective scavengers of reactive oxygen species (ROS) in terms of inhibition of 1) human low-density lipoprotein (LDL) peroxidation (measured by the diene conjugation method) and 2) DNA damage (measured by the formation of strand breaks in supercoiled OX-174 RFI DNA). In addition, the direct effect of E2 on the generation of individual ROS was also measured. By use of ROS scavengers, it was determined that lipoprotein peroxidation was predominantly due to superoxide (39%), with some contributions from hydrogen peroxide (23%) and peroxy (38%) radicals. E2 was a more effective inhibitor of peroxidation than all the ROS scavengers combined. In DNA damage, scavengers of hydrogen peroxide, hydroxyl, and superoxide radical offered significant protection (49–65%). E2 alone offered a similar degree of protection, and no additional effect was evident when it was combined with ROS scavengers. E2caused a significant reduction (37%) in the production of superoxide radical by bovine heart endothelial cells in culture but had no effect on the formation of either hydrogen peroxide or hydroxyl radicals. These studies show that 1) the protection offered by E2 in terms of lipid peroxidation could be due to its ability to inhibit generation of superoxide radical and prevent further chain propagation, and 2) in DNA damage protection, E2 mainly appears to inhibit chain propagation.

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