Brown Algae Fucoxanthin Is Hydrolyzed to Fucoxanthinol during Absorption by Caco-2 Human Intestinal Cells and Mice

The metabolic fate in mammals of dietary fucoxanthin, a major carotenoid in brown algae, is not known. We investigated the absorption and metabolism of fucoxanthin in differentiated Caco-2 human intestinal cells, a useful model for studying the absorption of dietary compounds by intestinal cells. Fucoxanthin was taken up by Caco-2 cells incubated with micellar fucoxanthin composed of 1 μmol/L fucoxanthin, 2 mmol/L sodium taurocholate, 100 μmol/L monoacylglycerol, 33.3 μmol/L fatty acids and 50 μmol/L lysophosphatidylcholine. Fucoxanthinol, the deacetylated product of fucoxanthin, was also found in both medium and cells, with its level increasing significantly in a time-dependent manner. No conjugated forms of fucoxanthin and fucoxanthinol were found in either medium or cells. In the animal study, fucoxanthinol (10.4 ± 5.3 nmol/L plasma, n = 4) was detected in plasma of mice 1 h after intubation of 40 nmol fucoxanthin. These results indicate that dietary fucoxanthin is incorporated as fucoxanthinol, the deacetylated form, from the digestive tract into the blood circulation system in mammals.