Carotene, / antioxidant activity

The antioxidant activities of carotenoids and other phytochemicals in the human body can be measured, or at least estimated, by a variety of techniques, in vitro, in vivo or ex vivo (Krinsky, 2001). Many studies describe the use of ex vivo methods to measure the oxidisability of low-density lipoprotein (LDL) particles after dietary intervention with carotene-rich foods. However, the difficulty with this approach is that complex plant foods usually also contain other carotenoids, ascorbate, flavonoids, and other compounds that have antioxidant activity, and it is difficult to attribute the results to any particular class of compounds. One study, in which subjects were given additional fruits and vegetables, demonstrated an increase in the resistance of LDL to oxidation (Hininger et al., 1997), but two other showed no effect (Chopra et al, 1996 van het Hof et al., 1999). These differing outcomes may have been due to systematic differences in the experimental protocols or in the populations studied (Krinsky, 2001), but the results do indicate the complexity of the problem, and the hazards of generalising too readily about the putative benefits of dietary antioxidants. 

FAROMBi E o and BRITTON G (1999) Antioxidant activity of palm oil carotenes in organic solution effects of strucmre and chemical reactivity . Food Chem, 64, 315-21. 

It has been established that carotenoid structure has a great influence in its antioxidant activity for example, canthaxanthin and astaxanthin show better antioxidant activities than 3-carotene or zeaxanthin. 3- 3 3-Carotene also showed prooxidant activity in oil-in-water emulsions evaluated by the formation of lipid hydroperoxides, hexanal, or 2-heptenal the activity was reverted with a- and y-tocopherol. Carotenoid antioxidant activity against radicals has been established. In order of decreasing activity, the results are lycopene > 3-cryptoxanthin > lutein = zeaxanthin > a-carotene > echineone > canthaxanthin = astaxanthin. ... 

Miller, N.J., Sampson, J., Candeias, L.P., Bramley, P.M., and Rice-Evans, C.A. 1996. Antioxidant activities of carotenes and xanthophylls. FEBS Lett. 384 240-242. 

Carrots (Daucus carota) are excellent sources of (3-carotene and vitamin A, although they have been reported to exert low antioxidant activity compared to some other vegetables (Al-Saikhan and others 1995 Cao and others 1996 Ramarathnam and others 1997 Vinson and others 1998 Beom and others 1998). However, boiling carrots for 30 min significantly improved their antioxidant activity toward coupled oxidation of (3-carotene and linolenic acid (Gazzani and others 1998). 

Fresh peppers are excellent sources of vitamins A and C, as well as neutral and acidic phenolic compounds (Howard and others 2000). Levels of these can vary by genotype and maturity and are influenced by growing conditions and processing (Mejia and others 1988 Howard and others 1994 Lee and others 1995 Daood and others 1996 Simmone and others 1997 Osuna-Garcia and others 1998 Markus and others 1999 Howard and others 2000). Peppers have been reported to be rich in the provitamin A carotenoids (3-carotene, a-carotene, and (3-cryptoxanthin (Minguez-Mosquera and Hornero-Mendez 1994 Markus and others 1999), as well as xanthophylls (Davies and others 1970 Markus and others 1999). Bell peppers have been shown to exert low antioxidant activity (Al-Saikhan and others 1995 Cao and others 1996 Vinson and others 1998) or may even act as pro-oxidants (Gazzani and others 1998). 

Teow CC, Truong V-D, McFeeters RF, Thompson RL, Pecota KV and Yencho GC. 2007. Antioxidant activities, phenolic and [betaj-carotene contents of sweet potato genotypes with varying flesh colours. Food Chem 103(3) 829-838. 

Terao J. 1989. Antioxidant activity of 3-carotene-related carotenoids in solution. Lipids 24 659-661. 

Matsufuji H, Nakamura H, Chino M, Takeda M (1998) Antioxidant activity of capsanthin and the fatty acid esters in paprika (Capsicum annuum). J Agric Food Chem 46 3468-3472 WaU MM, WaddeU CA, Bosland PW (2001) Variation in P-carotene and total carotenoid content in fruits of Capsicum. HortScience 36 746-749... 

Carotenoids are isoprenoid compounds that are biosynthesized only by plants and microorganisms. Some carotenoids (a- and p-carotene, p-cryptoxanthine) can be cleaved into vitamin A (retinol) by an enzyme in the small intestine. Carotenoids have been reported to present some effects in the prevention of cardiovascular diseases [410] and in the prevention of some kind of cancers [411]. Furthermore, antioxidant activity has been widely reported [411-414] but a switch to pro-oxidant activity can occur as a function of oxygen concentration [415,416]. 

Determination of the antioxidant activity in the system comprising p-carotene and linoleic acid is based on competitive oxidation of p-carotene during heat-induced auto-oxidation of hnoleic... 

Amarowicz R, Wanasrmdara U, Wanasundara J, Shahidi F. /Antioxidant activity of ethanolic extracts of faxseed in a 3-carotene-linoleate model system. Journal of Food Eipids. 1993 1111-117. 

Kanner et al. (1984) further showed that cysteine-Fe—NO is inhibitory to hemin or cysteine-Fe catalyzed oxidaticrn of /3-carotene. They explained the antioxidant activity of cysteine-Fe-NO and hemin-NO as the simultaneous quenching of free radicals [Eq. (1)] and decomposition of hydroperoxides (Eq. (2)]. The free radicals formed during decomposition of hydroperoxides are... 

The carotenoids are a group of lipid-soluble pigments responsible for the yellow, orange, and red colour of many plant materials. Most foods contain a variety of carotenoids that differ mainly in their content of double bonds and oxygen atoms over 400 different compounds are known. The most important among these is P-carotene. In addition to its excellent colouring properties, it is a precursor to vitamin A, and has antioxidant activity (which is believed to assist the prevention of certain forms of cancer). 

Moreover, DCQAs (1,5-, 3,4- and 4,5-DCQAs), with antioxidative activity, have been isolated from the leaves of garland (Chrysanthemum coronarium L.) [113], The garland Chrysanthemum coronarium L.) has been regarded as a health food in East Asia because the edible portions, such as leaf and stem, contain abundant -carotene, iron potassium, calcium, and dietary fiber. In addition to these common nutrients, some compounds responsible for the chemoprevention of cancers and other diseases are thought to be contained in garland. The antioxidative activity of DCQAs has been assayed by the decay curves of P-carotene. The antioxidative ability of 1 pg/ml these compounds are nearly equal to that of 0.1 pg/ml 3-/er/-butyl-4-hydroxyanisole (BHA). 

Several components with antioxidant activity are found in fruit juices. These include ascorbic acid, tocopherols (vitamin E), beta-carotene and flavonoids. Beta-carotene has antioxidant activity that can quench the singlet oxygen that can induce precancerous cellular changes. 

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