Effect of Lycopene on Formation of Low Density Lipoprotein-Copper Complex in Copper Catalyzed Peroxidation of Low Density Lipoprotein, as in vitro Experiment

Background: A great deal of evidence has indicated that oxidatively modified LDL plays a critical role in the initiation and progression of atherosclerosis. Antioxidants that can prevent LDL oxidation may act as antiatherogens. Copper is a candidate for oxidizing LDL in atherosclerotic lesions. The binding of copper ions to LDL is usually thought to be a prerequisite for LDL oxidation by copper. The aim of this study was to investigate effect of lycopene on copper bound to LDL and also effect of this binding on the susceptibility of LDL to oxidative modification. Methods: In this study, LDL was isolated from EDTA-plasma by ultracentrifugation using a single- step discontinuous gradient. Then lycopene was added to LDL and oxidizability of LDL was estimated by thiobarbitoric acid reactive substances (TBARS) after CuSo4 addition. Finally, the effect of lycopene on formation of LDL-copper complex by gel filtration was studied. Results: Our results showed that lycopene (as dose dependently) was suppressed the formation TBARS and LDL-copper complex. The lycopene with concentrations of 10 µM, 50 µM and 100 µM was reduced susceptibility of LDL to oxidative modification approximately by 31, 67 and 71 percent, respectively. Furthermore, the addition of lycopene to the mixture containing LDL and copper before incubation was prevented the formation LDL-copper complex, approximately by 38 percent.  Conclusion: The results of this investigation show that lycopene with inhibition of binding of copper to LDL may decrease the susceptibility of LDL oxidation to this ion and thus may have a role in ameliorating atherosclerosis.