title: Identification and quantification of apo-lycopenals in fruits, vegetables, and human plasma.
abstract: Research has suggested that lycopene may be metabolized by eccentric cleavage, catalyzed by beta-carotene oxygenase 2, 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'-, apo-8'-, apo-10'-, apo-12'-, apo-14'-, and apo-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 8 weeks. Apo-6'-, apo-8'-, apo-10'-, apo-12'-, and apo-14'-lycopenals were detected and quantified in all food products tested, as well as plasma. The sum of apo-lycopenals was 6.5 microg/100 g Roma tomato, 73.4 microg/100 g tomato paste, and 1.9 nmol/L 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.
authors.affiliation: Department of Food Science & Technology, 110 Parker Building, 2015 Fyffe Court, The Ohio State University, Columbus, Ohio 43210, USA.
authors.forename: Rachel E
authors.initials: RE
authors.lastname: Kopec
authors.forename: Ken M
authors.initials: KM
authors.lastname: Riedl
authors.forename: Earl H
authors.initials: EH
authors.lastname: Harrison
authors.forename: Robert W
authors.initials: RW
authors.lastname: Curley
authors.forename: Damian P
authors.initials: DP
authors.lastname: Hruszkewycz
authors.forename: Steven K
authors.initials: SK
authors.lastname: Clinton
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Schwartz
mesh_terms: D002338:Carotenoids / Q000032:analysis* / Q000097:blood; D002851:Chromatography, High Pressure Liquid; D005260:Female; D005638:Fruit / Q000737:chemistry*; D006801:Humans; D000077276:Lycopene; D008297:Male; D010936:Plant Extracts / Q000032:analysis*; D053719:Tandem Mass Spectrometry; D014675:Vegetables / Q000737:chemistry*
chemical_list: D010936:Plant Extracts; D002338:Carotenoids; D000077276:Lycopene