Anti-oxidants carotenoids

Nutritional ingredients (e.g., relatively small molecules, such as carotenoids, (pro)vitamins, anti-oxidants, preservatives, polyunsaturated fatty acids, aspartame, and tailored peptide mixes). 

A study on the photoprotective effect of the topical application of 2% vitamin E and 5% vitamin C in humans showed no effect with the application of each substance alone, but an enhanced photo-protective effect after applying vitamins E and C combined, which was attributed to the regeneration of vitamin E by vitamin C.20 This enhanced effect has also been shown with the topical application of a combination of 15% ascorbic acid and 1% a-tocopherol to porcine skin.21 The combined systemic supplementation of vitamins C and E was similarly able to reduce sunburn reactions22 and to increase the minimal erythema dose (MED), a measure for individual photosensitivity, more than supplementation with either vitamin E or vitamin C alone.23,24 An oral supplementation with an anti-oxidative combination of carotenoids (P-carotene and lycopene), vitamin C, vitamin E, selenium, and proanthocyanidins (Seresis , Pharmaton SA, Lugano, Switzerland) also reduced the development and grade of UVB-induced erythema 25... 

The interaction of carotenoids and carotenoid radicals with other anti-oxidants is of importance with respect to anti-oxidative and possibly pro-oxidative reactions of carotenoids. All the radical cations of the carotenoids studied reacted with vitamin C so as to repair the carotenoid (e.g. in methanol, CAR t AscH CAR + AscH -I- H ). hi polar environments the vitamin E radical cation is deprotonated (TOH —> TO -i- H ) and TO does not react with carotenoids, whereas in non-polar environments, TOH is converted into TOH by hydrocarbon carotenoids, hi aU solvents studied, singlet oxygen is efficiently quenched by carotenoids that have appropriate low-lying triplet energy levels O -i- CAR -> Oj -i- CAR". However, such reactions are stiU to be observed in vivo. 

There is much current debate about the relevance of such carotenoid repair processes to hydrocarbon carotenoids such as 8-carotene and lycopene in vivo where the parent carotenoid is unhkely to encounter the polar ascorbic acid. However, the cation radical, with a positive charge, maybe sufficiently polar and long-lived for such interactions to be possible. For the carotenoids found in the macula, where an efficient anti-oxidant process is crucial, the hydroxy carotenoids zeaxanthin, meso zeaxanthin and lutein are likely to be in a membrane orientation such that the corresponding cation radicals are efficiently repaired by the vitamin C (cf. vitamin E, below). 

These interactions of carotenoids with vitamins C and E, taken with the varying reduction potentials of the carotenoids discussed above, may well be relevant to the possible synergistic effects of some combinations of anti-oxidants. 

Bdhm F, Edge R, Land EJ, McGarvey DJ and Truscott TG (1997) Carotenoids enhance vitamin E anti-oxidant efficiency. J Am Chem Sod 19 621-622... 

Edge R, Land EJ, McGarvey D, Mulroy L and Tmscott TG (1998) Relative one-electron reduction potentials of carotenoid radical cations and the interactions of carotenoids with the vitamin E radical cation. J AmerChem Soc 120 4087-4090 Everett SA, Dennis MF, Patel KB, Maddix S, Kundu SC and Willson RL (1996) Scavengingofnitrogendioxide, thiyl, and sulphonyl free radicals by the nutritional anti-oxidant fi-carotene. J Biol Chem 271 3988-3994 Foote CS and Denny RW (1968) Chemistry of singlet oxygen. 

Absorption spectra of radical ions of polyenes of biological interest. J Chem Soc Farad Trans I 73 416 29 Liebler DC and McClure TD (1996) Anti-oxidant reactions of f -carotene Identification of carotenoid-radical adducts. Chem Res Toxicol 9 8-11... 

Mortensen A and Skibsted LH (1997b) Relative stabihty of carotenoid radical cations and homologue tocopheroxyl radicals. A real time kinetic study of anti-oxidant hierarchy. FEES Lett 417 261-266... 

Mortensen A and Skibsted LH (1998) Reactivity of /3-carotene towards peroxyl radicals studied by laser flash and steady-state photolysis. FEES Lett 426 392-396 Mortensen A, Skibsted LH, Sampson J, Rice-Evans C and Everett SA (1997) Comparative mechanisms and rates of free radical scavenging by carotenoid anti-oxidants. FEES Lett 418 91-91... 

Cruzeiri-Hansson L and Mouritsen OG (1988) Passive ion permeability of lipid membranes model via hpid-domain interfacial area. Biochim Biophys Acta 944 63-72 Edge R, McGarvey DJ and Trascott TG (1997) The carotenoids as anti-oxidants—a review. Photochem Photobiol B Biol 41 189-200... 

Garewal, H. S., Meysken, F., Friedman, S., Alberts, D., and Ransey, L. (1993). Oral cancer prevention The case for carotenoids and anti-oxidant nutrients. Prev. Med. 22, 701-711. 

Today s stars are pomegranate with exceptionally high antioxidant activity ( Packed with powerful antioxidants and vitamins, this ruby-red fruit has been shown to be a cttre-all for just about any ailment ), astaxanthin produced by some algae ( tmique anti-oxidant and king of the carotenoids ), green tea ( rejuvenate... 

Galano A, Vargas R, Martinez A (2010) Carotenoids can act as anti-oxidants by oxidizing the superoxide radical anion. PhysChem Chem Phys 12 193-200... 

Truscott TG (1996) p-Carotene and disease a suggested pro-oxidant and anti-oxidant mechanism and speculations concerning its role in cigarette smoking. J Photochem Photobiol B-Biol 35 233-235 Mayne ST (1996) p-carotene, carotenoids, and disease prevention in humans. FASEB J 10 690-701 Rock CL (1997) Carotenoids biology and treatment. Pharmacol Ther 75 185-197 Anonymous (1998) I ARC Handbooks of Cancer Prevention, Vol. 2 Carotenoids. lARC, Lyon Mayne ST (1998) p-Carotene, carotenoids and cancer prevention. Principles and Practice of Oncology Updates 12 1-15... 

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