Carotenoid radical interaction

Carotenoid radical formation and stabilization on silica-alumina occurs as a result of the electron transfer between carotenoid molecule and the Al3+ electron acceptor site. Both the three-pulse ESEEM spectrum (Figure 9.3a) and the HYSCORE spectrum (Figure 9.3b) of the canthaxanthin/ A1C13 sample contain a peak at the 27A1 Larmor frequency (3.75 MHz). The existence of electron transfer interactions between Al3+ ions and carotenoids in A1C13 solution can serve as a good model for similar interactions between adsorbed carotenoids and Al3+ Lewis acid sites on silica-alumina. 

D is the dipole-dipole interaction between the slow relaxing carotenoid radical and the fast relaxing Ti3+ ion r is the interspin distance... 

Burke, M., Edge, R., Land, E.J., and Truscott, T.G. 2001a. Characterisation of carotenoid radical cations in liposomal environments interaction with vitamin C. J. Photochem. Photobiol. B Biol. 60 1-6. 

Edge, R, Land, EJ, McGarvey, D, Mulroy, L, and Truscott, TG, 1998. Relative one-electron reduction potentials of carotenoid radical cations and the interactions of carotenoids with the vitamin E radical cation. J Am Chem Soc 120, 4087 1090. 

Edge, R. 8c Truscott, T.G. Carotenoids-Free Radical Interactions Spectrum 2000, 13, 12-20. 

Edge, R., Land, E.J., McGarvey, D., Mulroy, L., and Truscott, T.G. (1998) Relative one-electron reduction potentials of carotenoid radical cations and the interactions of carotenoids with the vitamin E radical cation, J. Am. Chem. Soc., 120, 4087 4090. Fleschner, C.R. (1995) Fatty acid composition of triacylglycerols, free fatty acid and phospholipids from bovine lens membrane fractions, Invest. Ophthal. Vis. Sci., 36, 261-264. Fraunfelder, F.T. (1982) Drug-Induced Ocular Side Effects and Drug Interactions, 2nd ed., Philadelphia Lea Febiger. 

Wu Y, Piekara-Sady L and Kispert LD(1991) Photochemically generated carotenoid radicals on Nafion film and silica gel An EPR and ENDOR study. Chem Phys Lett 180 573-577 Yeates TO, Komiya H, Chirino A, Rees DC, Allen JP and Feher G (1988) Structure of the reaction center from Rhodobacter sphaeroides R-26 and 2.4.1 Protein-cofactor (bacterio-chlorophyll, bacteriopheophytin, and carotenoid) interactions. Proc Natl Acad Sci USA 85 7993-7997 Young AJ (1991) The photoprotective role of carotenoids in higher plants. Physiol Plant 83 702-708 Young AJ and Frank HA (1996) Energy transfer reactions involving carotenoids Quenchingofchlorophyll fluorescence. J Photochem Photobiol B Biol 36 3-15... 

Carotenoid Radicals and the Interaction of Carotenoids with Active Oxygen Species... 

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. 

Grant JL, Kramer VJ, Ding R and Kispert LD (1988) Carotenoid cation radicals Electrochemical, optical and EPR study. J AmerChem Soc 110 2151-2157 Gust D, Moore TA, Moore AL, Jori G and Reddi E (1993) The photochemistry of Carotenoids Some photosynthetic and photomedical aspects. Ann New York Acad Sci 691 32-47 Hill TJ, Land EJ, McGarvey DJ, Schalch W, Tinkler JH and Tmscott TG (1995) Interactions between carotenoids and the CCI3O2 radical. J Am Chem Soc 117 8322-8326 Jeevarajan AS, Kispert LD, Chumanov G, Zhou C and Gotten TM (1996) Resonance Raman study of carotenoid radical cations. Chem Phys Lett 259 515-522 Lafferty J, Roach AC, Sinclair RS, Tmscott TG and Land EJ... 

Carotenoid radical cations are formulated as intermediates in various reactions between carotenoids and reactive oxygen species [50,52], Carotenoids may interact with free radicals in three different ways [50] ... 

Several in vitro studies have investigated interactions between carotenoids and vitamin C. It has been claimed that ascorbic acid can reduce the carotenoid radical cations in methanol according to Reaction 12.38 ... 

MORTENSEN A, SKIBSTED L H and TRUscoTT T G (2001) The interaction of dietary carotenoids with radical species , Arch Biochem Biophys, 385, 13-19. 

Spin trapping methods were also used to show that when carotenoid-P-cyclodextrin 1 1 inclusion complex is formed (Polyakov et al. 2004), cyclodextrin does not prevent the reaction of carotenoids with Fe3+ ions but does reduce their scavenging rate toward OOH radicals. This implies that different sites of the carotenoid interact with free radicals and the Fe3+ ions. Presumably, the OOH radical attacks only the cyclohexene ring of the carotenoid. This indicates that the torus-shaped cyclodextrins, Scheme 9.6, protects the incorporated carotenoids from reactive oxygen species. Since cyclodextrins are widely used as carriers and stabilizers of dietary carotenoids, this demonstrates a mechanism for their safe delivery to the cell membrane before reaction with oxygen species occurs. 

Ding, R., J. L. Grant et al. (1988). Carotenoid cation radicals produced by the interaction of carotenoids with iodine. J. Phys. Chem. 92 4600-4606. 

Krinsky, N. I. and S. M. Deneke (1982). Interaction of oxygen and oxy-radicals with carotenoids. J. Natl. Cancer Inst. 69(1) 205-210. 

INTERACTIONS OF CAROTENOIDS WITH FREE RADICALS 14.3.1 Sulfur-Containing Radicals... 

Interaction with Other Carotenoids 14.4.2.1 Radical Anions... 

Carotenoids interact with a number of free radicals either via electron (Equation 15.3) or hydrogen (Equation 15.4) transfer, or forming an addition complex (Equation 15.5) (El-Agamey et al., 2004b) ... 

In summation, as a result of interaction with free radicals, carotenoids can themselves become a source of free radicals and may induce further damaging reactions. 

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