Effect of Omeprazole on Ascorbate Free Radical Formation.

Ohara, Tadashi; Sasaki, Rikuko; Shibuya, Daisuke; Asaki, Shigeru; Toyot, Takayoshi

doi:10.1620/tjem.167.185

Cited by 4 publications

(2 citation statements)

References 9 publications

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“…In animal exper- iments, sepsis has also been shown to increase Asc •-, indicating the involvement of oxidative stress with this health problem (69). Sasaki et al have investigated in human serum the use of Asc •signal intensity in combination with measurements of AscHand DHA as an indicator of oxidative stress in human health problems that range from aging to xenobiotic metabolism (70)(71)(72)(73)(74). Consequently, the ascorbate radical level in biological systems may be useful for monitoring free radical reactions in vivo, particularly when free radical production is low and other methods are insensitive.…”

Section: Ascorbate Radical As a Marker Of Free Radical-mediated Oxidamentioning

confidence: 99%

Catalytic Metals, Ascorbate and Free Radicals: Combinations to Avoid

Buettner¹,

Jurkiewicz²

1996

Radiation Research

803

601

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Trace levels of transition metals can participate in the metal-catalyzed Haber-Weiss reaction (superoxide-driven Fenton reaction) as well as catalyze the oxidation of ascorbate. Generally ascorbate is thought of as an excellent reducing agent; it is able to serve as a donor antioxidant in free radical-mediated oxidation processes. However, as a reducing agent it is also able to reduce redox-active metals such as copper and iron, thereby increasing the pro-oxidant chemistry of these metals. Thus ascorbate can serve as both a pro-oxidant and an antioxidant. In general, at low ascorbate concentrations, ascorbate is prone to be a pro-oxidant, and at high concentrations, it will tend to be an antioxidant. Hence there is a crossover effect. We propose that the "position" of this crossover effect is a function of the catalytic metal concentration. In this presentation, we discuss: (1) the role of catalytic metals in free radical-mediated oxidations; (2) ascorbate as both a pro-oxidant and an antioxidant; (3) catalytic metal catalysis of ascorbate oxidation; (4) use of ascorbate to determine adventitious catalytic metal concentrations; (5) use of ascorbate radical as a marker of oxidative stress; and (6) use of ascorbate and iron as free radical pro-oxidants in photodynamic therapy of cancer.

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Section: Ascorbate Radical As a Marker Of Free Radical-mediated Oxidamentioning

confidence: 99%

Catalytic Metals, Ascorbate and Free Radicals: Combinations to Avoid

Buettner¹,

Jurkiewicz²

1996

Radiation Research

803

601

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show abstract

“…In a study using the electron spin resonance (ESR) method, we previously found that OPZ increases in the ESR signal intensity of ascorbate radical (AFR) in vitro and that OPZ acts like oxygen radicals in altering the K value of ascorbic acid, which can be used as an index of free radical exposure in vivo [3,4]. Vitamin E exerts an anti-oxidant action by preventing the lipid peroxidation of unsaturated fatty acids in phospholipids containing peroxy radicals in biological cell membranes [5], and it also has a direct effect on oxygen radicals such as ringlet oxygen (102), superoxide (02-), and hydroxy radical • OH [6,7].…”

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confidence: 99%