Mechanisms of Inactivation of Oxygen Species by Carotenoids
Although carotenoid pigments have been implicated as anti-carcinogenic compounds for several years, based on both epidemiological evidence (1) as well as experiments in animals (2,3), the exact mechanism whereby this widely distributed class of componds functions is still poorly understood. What appears to be important however, is the fact that many of the effects of carotenoids in vivo and in vitro can be observed with pigments that do not function as precursors of vitamin A (retinol). For example, beta-carotene may exert its biological effects merely by functioning as a precursor of retinal and retinol. On the other hand, there are carotenoid pigments, such as canthaxanthin (4,4’-diketo-beta-carotene) which also exhibit anti-carcinogenic properties and cannot be converted to retinol (Figure 1). Under these circumstances, we must look at the properties of the intact molecules in order to understand their functions.
KeywordsSinglet Oxygen Xanthine Oxidase Active Oxygen Species Peroxyl Radical Sister Chromatid Exchange
Unable to display preview. Download preview PDF.
- 10.J.R. Kanovsky and B. Axelrod, Singlet oxygen production by soybean lipoxygenase isozymes. J. Biol. Chem. 261, 1099–1104 (1986).Google Scholar
- 11.E. Cadenas. Oxidative stress and formation of excited species, in Oxidative Stress (H. Sies, Ed.) pp. 311–330. Academic Press, New York, 1985.Google Scholar
- 12.W. Bors, C. Michel and M. Saran. Inhibition of the bleaching of the carotenoid crocin. A rapid test for quantifying antioxidant activity. Biochim. Biophys. Acta 796, 312–319 (1984).Google Scholar
- 15.J.E. Packer, J.S. Mahood, V.O. Mora-Arellano, T.F. Slater, R.L. Willson, and B.S. Wolfenden. Free radicals and singlet oxygen scavengers: reaction of a peroxy-radical with beta-carotene, diphenylfuran and 1,4-diazobicyclo(2,2,2)-octane. Biochem. Biophys. Res. Commun. 98, 901–906 (1981).PubMedCrossRefGoogle Scholar
- 17.N.I. Krinsky. Carotenoid pigments: multiple mechanisms for coping with the stress of photosensitized oxidations. in Strategies of Microbial Life in Extreme Environments (M. Shilo, ed.) pp. 163–177, Dahlem Konferenzen, Berlin, 1979.Google Scholar
- 22.M. M. Mathews-Roth, Porphyrin photosensitiztion and carotenoid protection in mice; in vitro and in vivo studies. Photochem. Photobiol. 63–67 (1984).Google Scholar
- 26.P.A. Rubin, S. Welankiwar, and N.I. Krinsky. Unpublished observations (1987).Google Scholar