キンギョ Carassius auratus における Lutein および Zeaxanthin のケトカロテノイドヘの生体代謝

抄録

In order to determine which carotenoid is metaboized to astaxanthin, test diets containing either lutein or zeaxanthin were fed to goldfish for a period of 30 days.
In the integuments of goldfish fed on zeaxanthin, amounts of zeaxanthin (25.8 times), β-carotene triol (6.6), β-doradexanthin (5.0) and astaxanthin (3.1) increased significantly.
By contrast, when lutein was fed, there was an obvious in lutein (44.9), 3'-epilutein (31.8), α-carotene triol (7.6) and α-doradexanthin (9.5), the amount of astaxanthin decreased. Furthermore, β-doradexanthin was not detected.
These results are compatible with the pathways proposed by HATA et al. (1972). Moreover, the new intermediates, 3'-epilutein and α-carotene triol have been identified in the pathway from lutein to α-doradexanthin. It was concluded that the schemata for the metabolic pathways of lutein and zeaxanthin should be respectively as follows: lutein→3'-epilutein→α-carotene triol→α-doradexanthin; and zexanthin→β-carotene triol→β-doradexanthin→astaxanthin respectively.
The absence of β-doradexanthin and the decrease in hte astaxanthin content in the goldfish fed on lutein suggests that the goldfish is not able to convert α-structure to β-structure. This conclusion contradicts the pathway proposed by KATAYAMA et al. (1970).