Identification and Quantification of Apo-lycopenals in Fruits Vegetables and Human Plasma

摘要

Research has suggested that lycopene may be metabolized by eccentric cleavage, catalyzed by β-carotene oxygenase 2 (BCO2), resulting in the generation of apo-lycopenals. Apo-6′-lycopenal and apo-8′-lycopenal have been reported previously in raw tomato. We now show that several other apo-lycopenals are also present in raw and processed foods, as well as in human plasma. Apo-lycopenal standards were prepared by in vitro oxidation of lycopene, and a high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method using atmospheric pressure chemical ionization in negative mode was developed to separate and detect the apo-6′-, 8′-, 10′-, 12′-, 14′-, and 15′-lycopenal products formed in the reaction.Hexane/acetone extracts of raw tomato, red grapefruit, watermelon, and processed tomato products were analyzed, as well as plasma of individuals who had consumed tomato juice for eight weeks. Apo-6′-, 8′-, 10′-, 12′-, and 14′-lycopenals were detected and quantified in all food products tested, as well as plasma. The sum of apo-lycopenals was 6.5 µg/100 g ‘Roma’ tomato, 73.4 µg/100 g tomato paste, and 1.9 nmol/L of plasma. We conclude that several apo-lycopenals, in addition to apo-6′- and 8′-lycopenal, are present in lycopene containing foods. In addition, the presence of apo-lycopenals in plasma may derive from the absorption of apo-lycopenals directly from food and/or human metabolism.