Lycopene antioxidant

The antioxidant system in humans is a complex network composed by several enzymatic and nonenzymatic antioxidants. In addition to being an antioxidant, lycopene also exerts indirect antioxidant properties by inducing the production of cellular enzymes such as superoxide dismutase, glutathione S-transferase, and quinone reductase that also protect cells from reactive oxygen species and other electrophilic molecules (Goo and others 2007). 

Rao AV and Agarwal S. 2000. Role of antioxidant lycopene in cancer and heart disease. J Am Coll Nutr... 

Hsiao G., Fong T. H., Tzu N. H., Fin K. H., Chou D. S., and Sheu J. R. (2004). A potent antioxidant, lycopene, affords neuroprotection against microglia activation and focal cerebral ischemia in rats. In Vivo 18 351-356. 

FIG. 11 LDL oxidation and coronary heart disease (Rao and Balachandran, 2004). (Role of antioxidant lycopene in heart disease. Reprinted from Antioxidants and cardiovascular disease. 2004. R. Nath, M. Khullar, Singal P.K., eds., pp. 62-83. By permission of Narosa Publishing House.)... 

Fertile sources of carotenoids include carrots and leafy green vegetables such as spinach. Tomatoes contain significant amounts of the red carotenoid, lycopene. Although lycopene has no vitamin A activity, it is a particularly efficient antioxidant (see Antioxidants). Oxidation of carotenoids to biologically inactive xanthophyUs represents an important degradation pathway for these compounds (56). 

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. ... 

Sies, H. and Stahl, W., Lycopene antioxidant and biological effects and its bioavail-abihty in the human, Proc. Soc. Exp. Biol. Med., 218, 121, 1998. 

Fruifs and vegetables also contain ofher bioactive substances such as polyphenols (including well-known pigments anthocyanins, flavonols) and non-provitamin A carotenoids (mainly lycopene, lutein, and zeaxanthin) that may have protective effects on chronic diseases. Polyphenols and carotenoids are known to display antioxidant activities, counteracting oxidative alterations in cells. Besides these antioxidant properties, these colored bioactive substances may exert other actions on cell signaling and gene expression. 

Rao, A.V. and Agarwal, S., Bioavailability and in vivo antioxidant properties of lycopene from tomato products and their possible role in the prevention of cancer, Nutr. Cancer, 3, 199, 1998. 

Kim, H.S. and Lee, B.M., Protective effects of antioxidant supplementation on plasma lipid peroxidation in smokers, J. Toxicol. Environ. Health A, 63, 583, 2001. Gaziano, J.M. et al.. Supplementation with beta-carotene in vivo and in vitro does not inhibit low density lipoprotein oxidation. Atherosclerosis, 112, 187, 1995. Sutherland, W.H.F. et al.. Supplementation with tomato juice increases plasma lycopene but does not alter susceptibility to oxidation of low-density lipoproteins from renal transplant recipients, Clin. Nephrol, 52, 30, 1999. 

Takeoka, G.R., Processing effects on lycopene content and antioxidant activity of tomatoes, J. Agric. Food Chem., 49, 3713, 2001. 

The lag-phase measurement at 234 nm of the development of conjugated dienes on copper-stimulated LDL oxidation is used to define the oxidation resistance of different LDL samples (Esterbauer et al., 1992). During the lag phase, the antioxidants in LDL (vitamin E, carotenoids, ubiquinol-10) are consumed in a distinct sequence with a-tocopherol as the first followed by 7-tocopherol, thereafter the carotenoids cryptoxanthin, lycopene and finally /3-carotene. a-Tocopherol is the most prominent antioxidant of LDL (6.4 1.8 mol/mol LDL), whereas the concentration of the others 7-tocopherol, /3-carotene, lycopene, cryptoxanthin, zea-xanthin, lutein and phytofluene is only 1/10 to 1/300 of a-tocopherol. Since the tocopherols reside in the outer layer of the LDL molecule, protecting the monolayer of phospholipids and the carotenoids are in the inner core protecting the cholesterylesters, and the progression of oxidation is likely to occur from the aqueous interface inwards, it seems reasonable to assign to a-tocopherol the rank of the front-line antioxidant. In vivo, the LDL will also interact with the plasma water-soluble antioxidants in the circulation, not in the artery wall, as mentioned above. 

Other dietary factors implicated in prostate cancer include retinol, carotenoids, lycopene, and vitamin D consumption.5,6 Retinol, or vitamin A, intake, especially in men older than age 70, is correlated with an increased risk of prostate cancer, whereas intake of its precursor, [3-carotene, has a protective or neutral effect. Lycopene, obtained primarily from tomatoes, decreases the risk of prostate cancer in small cohort studies. The antioxidant vitamin E also may decrease the risk of prostate cancer. Men who developed prostate cancer in one cohort study had lower levels of l,25(OH)2-vitamin D than matched controls, although a prospective study did not support this.2 Clearly, dietary risk factors require further evaluation, but because fat and vitamins are modifiable risk factors, dietary intervention may be promising in prostate cancer prevention. 

One possible mechanism responsible for cooperative action of antioxidants is reduction of a semi-oxidized carotenoid by another antioxidant. Carotenoid cation radicals can be reduced, and therefore recycled to the parent molecule, by a-tocopherol, ascorbate, and melanins (Edge et al., 2000b El-Agamey et al., 2004b) (Figure 15.5). Interestingly, lycopene can reduce radical cations of other carotenoids, such as astaxanthin, (3-carotene, lutein, and zeaxanthin (Edge et al., 1998). 

Breinholt, V., S. T. Lauridsen, B. Daneshvar, and J. Jakobsen. 2000. Dose-response effects of lycopene on selected drug-metabolizing and antioxidant enzymes in the rat. Cancer Lett 154(2) 201-210. 

Lian, F. and X. D. Wang. 2008. Apo-lO -lycopenoic acid, an enzymatic metabolite of lycopene, induces Nrf2-mediated expression of phase II detoxifying/antioxidant enzymes in human bronchial epithelial cells. Int J Cancer (in press). 

Oxidant and Antioxidant Effects of Lycopene in Prostate Cell Lines.443... 

Population studies associate tomato consumption with reduced risk to prostate cancer. The most positive associations have come from cohort studies performed before the prostate-specific antigen (PSA)-screening era, and these studies have suggested that the tomato/lycopene effect was the strongest for clinically relevant prostate cancers (Giovannucci 2007). Small human studies have shown in vivo antioxidant effects for tomato products but evidence for lycopene alone is weak (Chen et al. 2001, Porrini and Riso 2000, Riso et al. 2004, Zhao et al. 2006). Animal and tissue culture studies have been... 

---