Isolation and structural elucidation of different geometrical isomers of lycopene.

Five geometrical isomers of lycopene were isolated from a photoisomerized mixture on a semi-preparative C30 column and characterized by UV-vis spectroscopy, mass spectroscopy, and nuclear magnetic resonance (NMR) spectroscopy. 1H NMR and 2D NMR measurements were used to unambiguously assign the double bond configuration of five isomers: (5Z,9'Z)-, (9Z)-, (5Z,9Z)-, (all-E)-, and (5Z)-lycopene. This will allow other laboratories to use the results for their C30 HPLC.

Cleavage products of lycopene produced by in vitro oxidations: characterization and mechanisms of formation.

The aim of this study was to produce in vitro oxidation products of lycopene, which could be possible in vivo metabolites. An oxidation of lycopene with potassium permanganate gave a range of lycopene degradation compounds resulting from the oxidative cleavage of one or two carbon-carbon double bonds. Eleven apo-lycopenals/ones and six apo-carotendials were obtained and tentatively characterized by HPLC-DAD-MS.