抄録
Lycopene has aroused public interest owing to its role in preventing oxidative damage, cancer and aging, etc. These activities are considered to be due to its high ability of scavenging active oxygen species. In the present work, we have examined the products formed by the photosensitized oxygenation, hydrogen peroxide oxidation, m-chloroperbenzoic acid (mCPBA) oxidation and peroxinitrite oxidation of lycopene. We also isolated two oxygenated lycopenes with a novel five-membered ring end-group from tomato puree. In photosensitized oxygenation (singlet oxygen oxidation), we isolated apo-6'-lycopenal and 6-methyl-5-hepten-2-one. The reaction is supposed to proceed via 1,2 addition of singlet oxygen to 5,6 double bond of lycopene. In hydrogen peroxide and m CPBA oxidation, we isolated oxygenated lycopenes with a novel five-membered ring end-group (2,6-cyclolycopene-1,5-diol, 2,6-cyclolycopene-1,5-epoxide, 1,16-didehydro-2,6-cyclolycopene-5-ol and 1-methoxy-2,6-cyclolycopene-5-ol). It is proposed that the formation for these compounds occurs by rearrangement of lycopene 5,6-epoxide. In peroxinirite oxidation, we could classify the products into three types, 1) oxidative cleavage products, 2) non-cleavage oxidative products that have C40 carbon skeleton, and 3) Z-isomers of lycopene. The reaction pathways to form these compounds will be discussed.
