Article
J. Agric. Food Chem., Vol. 58, No. 6, 2010 3295
deliberate biosynthesis, these aldehydes could be the result of
a nonspecific lipoxygenase cleavage (33, 34) or produced from
photo-oxidation in the fruit (35).
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The presence of apo-lycopenals in plasma could be due to
enzymatic cleavage of lycopene. It has been demonstrated that
BCO1 cleaves β-carotene at the 15-150 double bond to produce
two molecules of retinal in vertebrates (14). In addition, a second
carotenoid oxygenase (BCO2) has been shown to eccentrically
cleave β-carotene to produce β-apo-100-carotenal (15). In vitro,
BCO2 from ferret has also been shown to cleave both β-carotene
and lycopene at the 90-100 double bond (18). However, a single
cleavage site would not explain the array of aldehydes that we
observed in plasma.
The feeding of lycopene (as Lycovit 10%) to ferrets resulted in
the detection of apo-100-lycopenol in lung tissue (18). This alcohol
was presumed to be a metabolite of the aldehyde (apo-100-
lycopenal) formed enzymatically in vivo. In addition, the liver
of rats consuming a lycopene-containing diet for 30 days pro-
duced apo-80-lycopenal and putative apo-120-lycopenal in this
tissue (19, 36). These products were also hypothesized to be the
result of enzymatic cleavage in the animal.
In summary, we have observed a full series of apo-lycopenals in
foods, processed food products, and analytical grade lycopene
standard. In addition, we have documented the presence of
multiple apo-lycopenals in the plasma of humans consuming
tomato juice. This evidence suggests that these products may in
fact be absorbed from the food and not solely a product of
metabolism in vivo. The presence of apo-lycopenals in the
plasma, either from the diet or as metabolic products, supports
a hypothesis that these compounds may have bioactivity and
potentially mediate some of the health-promoting beneficial
effects proposed for tomato products. In addition, the develop-
ment of analytical methods for the measurement of apo-lycopenals
in mammalian systems provides a tool for the investigation of
lycopene metabolism. The continued improvement of analytical
approaches provides investigators with new approaches that will
help to determine the importance of apo-lycopenals from the diet
or as a product of enzymatic cleavage in vivo.
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