Lycopene: Metabolism and Functional Aspects

Abstract

Lycopene is the most abundant carotenoid found in human serum and has been recognized as the most effective antioxidant among all the carotenoids. Lycopene has 11 conjugated double bonds in its structure. However, lycopene occurs naturally in the all trans form in the dietary sources, found in as many as 18 different isometric forms in human serum and prostate cells mostly in cis form. However, the absolute concentrations of individual carotenoids within specific lipoprotein classes have not been reported; relative distribution of β-carotene, α-carotene, and lycopene among the very low-density lipoprotein (VLDL), low-density lipoprotein (LDL), and high-density lipoprotein (HDL) was similar, with 58–73% in LDL, 17–26% in HDL, and 10–16% in VLDL when separated by conventional sequential flotation ultracentrifugation and quantified by high-performance liquid chromatography. Lycopene has also been found helpful in elimination of xenobiotics through stool or urine. Lycopene alters hormone and growth factor signalling including IFG-1 (31.5% decrease in serum IFG-1 levels) which is associated with cell proliferation. However its stability is a critical factor for its functional aspects. Physical and chemical factors like elevated temperature, exposure to oxygen and light, metallic ions (e.g., Cu2+ and Fe3+), extreme in pH, and active surfaces affect its stability.