Scavenging effect of tea catechins and their epimers on superoxide anion radicals generated by a hypoxanthine and xanthine oxidase system
✍ Scribed by Unno, Tomonori; Sugimoto, Akio; Kakuda, Takami
- Publisher
- John Wiley and Sons
- Year
- 2000
- Tongue
- English
- Weight
- 116 KB
- Volume
- 80
- Category
- Article
- ISSN
- 0022-5142
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✦ Synopsis
Catechins are a major group of polyphenolic compounds contained in abundance in green tea. Using electron spin resonance spectroscopy along with a spin-trapping agent, the scavenging effect of tea catechins and their corresponding epimers against superoxide anion radicals generated by a hypoxanthine and xanthine oxidase reaction system was evaluated. The presence of 3',4',5'-trihydroxyl groups attached to the B-ring of the ¯avan skeleton of tea catechins elevated their radical-scavenging ef®ciency in comparison to those with 3',4'-dihydroxyl groups. There were no signi®cant differences between the four dominant tea catechins and their corresponding epimers with regard to radicalscavenging ability. Under the different spin-trapping agent concentrations, the sigmoid curves of reducing spin-trapping adducts produced by tea catechins were shifted leftward, suggesting that a likely possible action of tea catechins is to scavenge superoxide anion radicals directly, not to inhibit the function of xanthine oxidase. Although caffeine is also known as a major ingredient of tea, its superoxide anion radical-scavenging effect was much weaker than that of the catechin family. It is concluded that tea catechins and their epimers serve as powerful antioxidants for directly eliminating superoxide anion radicals, and may be useful in the prevention of diseases relating to in vivo oxidative stress.