Bioavailability and metabolism of fucoxanthin in rats: structural characterization of metabolites by LC-MS (APCI)

This study reports bioavailability and metabolism
of fucoxanthin (FUCO) from brown algae Padina
tetrastromatica in rats. Rats were divided into two
groups (n = 25/group). Group one was fed basal diet
(control) while the group two received retinol deficient diet
(RD group) for 8 weeks. After confirmed RD in blood
(0.53 lmol/l), rats were further sub-grouped (n = 5/sub
group), intubated a dose of FUCO (0.83 lmol) and killed
after 0, 2, 4, 6 and 8 h. The plasma levels (area under
curve/8 h) of FUCO (fucoxanthinol (FUOH) ? amarouciaxanthin
(AAx)) was 2.93 (RD group) and 2.74 pmol/dl
(control), respectively. No newly formed retinol was
detected in RD rats intubated with FUCO. Besides FUOH
(m/z 617 (M?H)?) and AAx (m/z 617 (M?H-)?), other
deacetylated, hydrolyzed and demethylated metabolites of
bearing molecular mass at m/z 600.6 (FUOH–H2O), m/z
597 (AAx–H2O), m/z 579 (AAx–2H2O?1), m/z 551 (AAx–
2H2O–2CH3?2) and m/z 523 (AAx–2H2O–4CH3?4) were
also detected in plasma and liver by LC-MS (APCI).
Although biological functions of FUCO metabolites need
thorough investigation, this is the first detailed report on
FUCO metabolites in rats.