Generation of Hydrogen Peroxide, Superoxide Anion and the Hydroxyl Free Radical from Polyphenols and Active Benzene Metabolites: Their Possible Role in Mutagenesis

1994 ◽  
Vol 1 (2) ◽  
pp. 125-130
Author(s):  
Shern-Fwu Lee ◽  
Jen-Kun Lin
Keyword(s):  
Hydrogen Peroxide ◽  
Free Radical ◽  
Superoxide Anion ◽  
Hydroxyl Free Radical

Mechanism of Hydrogen Peroxide and Hydroxyl Free Radical–Induced Intracellular Acidification in Cultured Rat Cardiac Myoblasts

1996 ◽  
Vol 78 (4) ◽  
pp. 564-572 ◽  
Author(s):  
Mei-Lin Wu ◽  
Ke-Li Tsai ◽  
Seu-Mei Wang ◽  
Jiahn-Chun Wu ◽  
Bor-Sen Wang ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Free Radical ◽  
Intracellular Acidification ◽  
Hydroxyl Free Radical ◽  
Cardiac Myoblasts

Evaluation of antioxidant activity of Melothria maderaspatana in vitro

2010 ◽  
Vol 5 (2) ◽  
pp. 224-230 ◽  
Author(s):  
Boobalan Raja ◽  
Kodukkur Pugalendi
Keyword(s):  
Hydrogen Peroxide ◽  
Antioxidant Activity ◽  
Free Radical ◽  
Hydroxyl Radical ◽  
Superoxide Anion ◽  
Radical Scavenging ◽  
Reducing Power ◽  
Free Radical Scavenging ◽  
Melothria Maderaspatana

AbstractIn this study, an aqueous extract of leaves from Melothria maderaspatana was tested for in vitro antioxidant activity. Free radical scavenging assays, such as hydroxyl radical, hydrogen peroxide, superoxide anion radical and 2,2-diphenyl-1-picryl hydrazyl (DPPH), 2,2’-azinobis-(3-ethyl-enzothiazoline-6-sulfonic acid) (ABTS) radical scavenging, and reducing power assay, were studied. The extract effectively scavenged hydroxyl radical, hydrogen peroxide and superoxide anion radicals. It also scavenged DPPH and ABTS radicals. Furthermore, it was found to have reducing power. All concentrations of leaf extract exhibited free radical scavenging and antioxidant power, and the preventive effects were in a dose-dependent manner. The antioxidant activities of the above were compared to standard antioxidants such as butylated hydroxytoluene (BHT), ascorbic acid, and α-tocopherol. The results obtained in the present study indicate that the M. maderaspatana extract could be considered a potential source of natural antioxidant.

Hydroxyl free radical production by the reaction of N-methyl-N′-nitro-N-nitrosoguanidine with hydrogen peroxide without exposure to light

1992 ◽  
Vol 70 (3-4) ◽  
pp. 262-268 ◽  
Author(s):  
Tomiko Mikuni ◽  
Masaharu Tatsuta ◽  
Mikiharu Kamachi
Keyword(s):  
Hydrogen Peroxide ◽  
Free Radical ◽  
Nucleophilic Attack ◽  
Peroxynitrous Acid ◽  
Nitrite Ion ◽  
Hydroxyl Free Radical ◽  
Spin Resonance ◽  
Resonance Spin ◽  
Layer Chromatography ◽  
Spin Trapping Technique

We examined hydroxyl free radical (∙OH) production in the mixture of H2O2 and N-methyl-N′-nitro-N-nitrosoguanidine (MNNG) without exposure to light using the electron spin resonance spin-trapping technique. When the mixtures were protected from exposure to light, ∙OH was formed at pH 6.5 and above; it was not formed at pH 5.0 and below, consistent with our previous report. The amount of ∙OH trapped depended on the concentrations of MNNG and H2O2 and the pH. Nitrite ion was also detected colorimetrically at pH 6.5 and above, but not detected at pH 5.0 and below in the mixtures without exposure to light. Moreover, its production depended on the concentrations of MNNG and H2O2 and the pH. The formation of N-methyl-N′-nitroguanidine in the mixture at pH 7.8 was confirmed by thin-layer chromatography and melting point. These results suggest that nucleophilic attack by H2O2 on the nitroso nitrogen of MNNG results in the formation of N-methyl-N′-nitroguanidine and peroxynitrous acid, which degrades homolytically to yield ∙OH and nitrogen dioxide, resulting in the production of nitrite ion, at pH 6.5 and above without exposure to light.Key words: N-methyl-N′-nitro-N-nitrosoguanidine, hydrogen peroxide, hydroxyl free radical, peroxynitrous acid.

Bioactive Composition of Pig Laryngeal Cartilage Extracts and Their Free Radical-scavenging Activity

2006 ◽  
Vol 12 (5) ◽  
pp. 371-377 ◽  
Author(s):  
Shuang-li Xiong ◽  
Zheng-yu Jin ◽  
An-lin Li
Keyword(s):  
Free Radical ◽  
Amino Acid ◽  
Superoxide Anion ◽  
Radical Scavenging Activity ◽  
Radical Scavenging ◽  
Free Radical Scavenging ◽  
Free Radical Scavenging Activity ◽  
Scavenging Activity ◽  
Laryngeal Cartilage ◽  
Hydroxyl Free Radical

This work focused on amino acid and mineral element analysis of pig laryngeal cartilage. Papain and DEAE-Sepharose fast flow ion exchange chromatography were used to hydrolyase cartilage and purify hydrolysate. Further study was performed to compare the free radical-scavenging activity of various fractions. Cartilage is abundant in bioactive amino acids such as glycine, glutamic acid and arginine and minerals such as calcium, magnesium and iron. Four polysaccahrides attached peptides and one peptide were isolated from hydrolysate. Weak 2,2-diphenyl-1-picryhydrazyl free radical scavenging activities of all substances were observed. Other fractions showed hydroxyl free radical and superoxide anion free radical scavenging ability in a concentration-dependent manner except fraction A. The hydroxyl free radical scavenging activity of tested samples decreased in the following order: fraction C crude chondroitin sulphate (ChS) peptide fraction B semi-purified ChS purified ChS. Significant differences were observed between purified ChS and other fractions (P 0.01). For superoxide anion free radical the order was: peptide purified ChS semi-purified ChS crude ChS fraction C fraction B. The peptide was significantly higher than purified ChS (P 0.01), which was significantly higher than the other components (P 0.01). According to the results, polysaccharides, ChS, amino acid and peptide present in cartilage had important bioactivity.

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