Antioxidant behaviour of caffeine: efficient scavenging of hydroxyl radicals

• Published in: Food and chemical toxicology Vol. 29; no. 1; p. 1
• Main Authors: Shi, X, Dalal, N S, Jain, A C
• Format: Journal Article
• Language: English
• Published: England 01-01-1991
• Subjects: Antioxidants - chemistry; Caffeine - chemistry; Cyclic N-Oxides - chemistry; Electron Spin Resonance Spectroscopy; Ethanol - chemistry; Free Radicals; Hydrogen Peroxide - chemistry; Hydroxides - chemistry; Hydroxyl Radical; Iron - chemistry; NADP - chemistry
• ISSN: 0278-6915
• DOI: 10.1016/0278-6915(91)90056-D

Considerable controversy exists in the literature regarding the toxicity of coffee, including its possible carcinogenic and anticarcinogenic properties. This study reports on the reaction of 1,3,7-trimethylxanthine (caffeine) with the hydroxyl radical (.OH), as investigated by electron spin resonance (ESR) spin trapping. The .OH was generated by the Fenton reaction (Fe2+ + H2O2) as well as by the reaction of chromium(V) with H2O2. The results show that caffeine effectively scavenges .OH with a reaction rate constant of approximately 5.9 x 10(9) M-1 sec-1 that is comparable with those of other efficient .OH radical scavengers. ESR measurements provide evidence that a caffeine-derived oxygen-centred radical is formed in the reaction of caffeine with .OH and suggest a biochemical basis for the understanding of the reported anticarcinogenic properties of caffeine and related methylxanthine compounds.