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KMID : 1007520020110050574
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Food Science and Biotechnology
2002 Volume.11 No. 5 p.574 ~ p.581
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Lycopene-Biochemistry and Functionality
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Shi, John
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Abstract
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Lycopepe is the major carotenoid pigment in tomatoes. Lycopene is found predominantly in the chromoplasts of plant tissues. Its biosynthesis increases as chloroplasts undergo a transformation to chromoplasts. With its acyclic structure and large array of conjugated double bonds, lycopene exhibits distinct biological properties to quench the energy of deleterious forms of oxygen and to scavenge a large spectrum of free radicals. Lycopene may provide protection against a broad range of epithelial cancers. Lycopene has been reported to increase the survival rate of mice exposed to X-ray radiation, and has direct stimulatory effects on the response of the immune system. This may involve an antioxidant action to reduce the ´susceptibility of lymphocyte DNA to oxidative damage, and to form the basis of a protective action against cancer, HIV and AIDS. Inhibition of cancer cell growth by lycopene has been extensively demonstrated in tissue culture experiments. The free radical quenching constant of lycopene was found to be more than double that of β-carotene and 10 times more than that of α-tocopherol. Lycopene is known to exist in a variety of geometric isomers, including all-trans, mono-cis, and poly-cis forms. The all-trans configuration predominates in fresh tomatoes and gradually isomerizes to cis- forms upon processing of tomato products. The cis-isomers are better absorbed by the human body than all- trans form. Although lycopene is readily absorbed from tomato products, there are various factors in the diet which may increase or decrease absorption. Information on lycopene bioavailability is limited and the pharmacokinetic properties of lycopene remain poorly understood. The lack of knowledge as to how lycopene functions in the human body have made it difficult to establish a clear and sound bioavailibility pattern of lycopene in foods. Further research on the bioavailability, metabolism, and pharmacology need to be done to reveal the mechanism of lycopene in the human diet, and the in-vivo metabolism of lycopene.
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