TY - JOUR
T1 - Biotransformation of fucoxanthinol into amarouciaxanthin a in mice and HepG2 cells
T2 - Formation and cytotoxicity of fucoxanthin metabolites
AU - Asai, Akira
AU - Sugawara, Tatsuya
AU - Ono, Hiroshi
AU - Nagao, Akihiko
N1 - Copyright:
Copyright 2008 Elsevier B.V., All rights reserved.
PY - 2004/2
Y1 - 2004/2
N2 - Fucoxanthin, a major carotenoid in edible brown algae, potentially inhibits the proliferation of human prostate cancer cells via apoptosis induction. However, it has been postulated that dietary fucoxanthin is hydrolyzed into fucoxanthinol in the gastrointestinal tract before absorption in the intestine. In the present study, we investigated the further biotransformation of orally administered fucoxanthin and estimated the cytotoxicity of fucoxanthin metabolites on PC-3 human prostate cancer cells. After the oral administration of fucoxanthin in mice, two metabolites, fucoxanthinol and an unknown metabolite, were found in the plasma and liver. The unknown metabolite was isolated from the incubation mixture of fucoxanthinol and mouse liver preparation (10,000g supernatant of homogenates), and a series of instrumental analyses identified it as amarouciaxanthin A [(3S,5R,6′S)-3,5,6′-trihydroxy-6,7-didehydro-5,6,7′, 8′-tetrahydro-β,ε-carotene-3′,8′-dione]. The conversion of fucoxanthinol into amarouciaxanthin A was predominantly shown in liver microsomes. This dehydrogenation/isomerization of the 5,6-epoxy-3-hydroxy-5,6-dihydro-β end group of fucoxanthinol into the 6′-hydroxy-3′-oxo-ε end group of amarouciaxanthin A required NAD(P)+ as a cofactor, and the optimal pH for the conversion was 9.5 to 10.0. Fucoxanthinol supplemented to culture medium via HepG2 cells was also converted into amarouciaxanthin A. The 50% inhibitory concentrations on the proliferation of PC-3 human prostate cancer cells were 3.0, 2.0, and 4.6 μM for fucoxanthin, fucoxanthinol, and amarouciaxanthin A, respectively. To our knowledge, this is the first report on the enzymatic dehydrogenation of a 3-hydroxyl end group of xanthophylls in mammals.
AB - Fucoxanthin, a major carotenoid in edible brown algae, potentially inhibits the proliferation of human prostate cancer cells via apoptosis induction. However, it has been postulated that dietary fucoxanthin is hydrolyzed into fucoxanthinol in the gastrointestinal tract before absorption in the intestine. In the present study, we investigated the further biotransformation of orally administered fucoxanthin and estimated the cytotoxicity of fucoxanthin metabolites on PC-3 human prostate cancer cells. After the oral administration of fucoxanthin in mice, two metabolites, fucoxanthinol and an unknown metabolite, were found in the plasma and liver. The unknown metabolite was isolated from the incubation mixture of fucoxanthinol and mouse liver preparation (10,000g supernatant of homogenates), and a series of instrumental analyses identified it as amarouciaxanthin A [(3S,5R,6′S)-3,5,6′-trihydroxy-6,7-didehydro-5,6,7′, 8′-tetrahydro-β,ε-carotene-3′,8′-dione]. The conversion of fucoxanthinol into amarouciaxanthin A was predominantly shown in liver microsomes. This dehydrogenation/isomerization of the 5,6-epoxy-3-hydroxy-5,6-dihydro-β end group of fucoxanthinol into the 6′-hydroxy-3′-oxo-ε end group of amarouciaxanthin A required NAD(P)+ as a cofactor, and the optimal pH for the conversion was 9.5 to 10.0. Fucoxanthinol supplemented to culture medium via HepG2 cells was also converted into amarouciaxanthin A. The 50% inhibitory concentrations on the proliferation of PC-3 human prostate cancer cells were 3.0, 2.0, and 4.6 μM for fucoxanthin, fucoxanthinol, and amarouciaxanthin A, respectively. To our knowledge, this is the first report on the enzymatic dehydrogenation of a 3-hydroxyl end group of xanthophylls in mammals.
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U2 - 10.1124/dmd.32.2.205
DO - 10.1124/dmd.32.2.205
M3 - Article
C2 - 14744942
AN - SCOPUS:0842304213
VL - 32
SP - 205
EP - 211
JO - Drug Metabolism and Disposition
JF - Drug Metabolism and Disposition
SN - 0090-9556
IS - 2
ER -