Lycopene biological activity

Since lycopene lacks the (3-ionic ring structure, unlike (3-carotene, it lacks provitamin A activity. The biological activity of lycopene is thought to be primarily due to its antioxidant properties. However, other mechanisms, such as facilitating gap junction communication (GJC) (Aust et al, 2003 Heber, 2002 Wertz et al, 2004 Zhang et al, 1991, 1992), stimulation of the immune system (Chew and Park, 2004 Heber, 2002 Heber and Lu, 2002 Kim et al, 2004 Wertz et al, 2004), endocrine-mediated pathways... 

The biological activities of carotenoids, such as (3-carotene, are related to their provitamin A activity within the body (Clinton, 1998). Since lycopene lacks the (3-ionic ring structure, it does not have any provitamin A activity (Stahl and Sies, 1996). The biological effects of lycopene in humans have therefore been attributed to mechanisms other than vitamin A. Two major hypotheses have been proposed to explain the anticarcinogenic and antiatherogenic activities of lycopene oxidative and nonoxidative mechanisms. The proposed mechanisms for the role of lycopene in the prevention of chronic diseases are summarized in Figure 6. 

III). Lycopene was not detected in the untreated fruits and it is not normally present in mature grapefruit (13). The biological activity was also correlated with the logarithm of the... 

Despite having no provitamin A function, carotenoids such as lycopene and lutein are still biologically active. High serum lycopene... 

Mein JR, Lian F, Wang X-D (2008) Biological activity of lycopene metabolites implications for cancer prevention. Nutr Rev 66 667... 

Raoa AV, Ali A (2007) Biologically active phytochemicals in human health lycopene. Int J Food Properties 10 279... 

Other Human Tissues. Details of extraction procedures and isocratic as well as RP-HPLC analysis of carotenoids present in various human tissues have been summarized by Parker (218) and by Schmitz et al. (219). Cis and trans isomers of carotenoids may have different biological activities. Thus the isomeric composition of lycopene and P-carotene was determined in the serum of healthy volunteers and in seven human tissues obtained by autopsy soon after death, using RP-HPLC on a Merck 5-p.m C18 end-capped column with a solvent mixture of CH3OH/CH3CN/CH2CI2/H2O) (7/7/2/0.16) and a photodiode array detector (220). 

A true assessment of the relationship between nutritional quality and health benefits of dietary lycopene depends not only on the total lycopene content, but also on the distribution of lycopene isomers. Better characterization and quantification of lycopene isomers would provide better insight into the potential nutritional quality and health benefits. The control of lycopene oxidation and isomerization during production and storage can be of benefit improving the retention biological activity and health-promoting effect. 

The nature of the supplements used It has been suggested that the synthetic forms used in most trials may have different biological activity or potency from natural forms of these vitamins, although trials using the natural forms have not found different clinical effects. The type of isomer used has also been questioned (e.g., /3-carotene versus other carotenoids such as lycopene or lutein or a-tocopherol versus 7-tocopherol). Trials have not investigated other potentially beneficial antioxidants in foods, such as flavonoids and lycopenes. 

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). 

The underlying mechanisms involved in the activities of carotenoid oxidation products are due either to a possible role as precursors of retinoids that would be the active species for positive effects or to their own specific activities. This latter case is illustrated by the activity of non-provitamin A carotenoid oxidation products such as those derived from lycopene. However, biological effects of carotenoid oxidation products other than retinoids are only hypothesized in vivo in humans, which hypothesis has been used as the basic principle to justify in vitro studies of these compounds. 

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