THE STUDY OF KINETIC INHIBITION OF COPPER (II)-INDUCED OXIDATION OF LOW-DENSITY LIPOPROTEIN BY LYCOPENE

Epidemiological studies have shown a decreased risk of atherosclerosis associated with the intake of fruits and vegetables rich in lipophilic compounds, but the mechanism was not clear. In the present work, the effect of lycopene on copper induced oxidation of isolated low-density lipoprotein (LDL) and the related mechanism were investigated. LDL was isolated from plasma by ultracentrifugation. Then lycopene was added to LDL samples and LDL oxidation estimated by monitoring the formation of conjugated diene after CuSO4 addition. Lycopene was found to inhibit copper induced oxidation kinetically, as characterized by the prolongation of the lag-time and or t(1/2) and also the decrease of maximal rate of conjugated diene formation. The results of this investigation show that lycopene may increase radicals formation time in LDL and thus decrease the susceptibility of LDL oxidation induced by copper (II). This mechanism may be a reason for lycopene effect in ameliorating atherosclerosis. PRACTICAL APPLICATIONS Lycopene belongs to a class referred as carotenoids. Carotenoides are yellow, orange and red pigments synthesized by plants. In plants, their function is to absorb light in photosynthesis and protecting plants against photosensitization. Lycopene found in human plasma, as the result of ingesting plants. Tomatoes and tomato products (like tomato sauce and tomato paste) are the single best source of lycopene. Studies have shown lycopene to possess superior antioxidant abilities in comparison with other carotenoids. It has the ability to quench singlet oxygen and prevent oxidative damage to other molecules and cellular structures because of its unique structure of: 11 conjugated double bonds and no cyclic groups. Because of this role, believe that lycopene may profoundly influence the evolution of several chronic diseases in a tissue-specific manner.