The Presence and Origin of an Apocarotenoid, Galloxanthin in Ayu Plecoglossus altivelis

Abstract

An apocarotenoid, (3 R)-galloxanthin, (3 R)-10′-apo-β-carotene-3,10′-diol, (1.1% of total carotenoids) has been isolated and identified from the integuments of wild mature koayu Plecoglossus altivelis. This is the first report of the occurrence of galloxanthin in fish. Feeding experiments were carried out on young koayu with β-carotene, canthaxanthin, (3 R)-β-cryptoxanthin, (3 R,3′ R)-astaxanthin, (3 S,3′ S)-astaxanthin, (3 R,3′ R)-zeaxanthin, lutein A, and fucoxanthin. In the integuments, canthaxanthin and (3 R)-β-cryptoxanthin were directly accumulated, but neither β-carotene nor fucoxanthin were accumulated. Lutein A was metabolized to lutein B. (3 R)-Galloxanthin was produced by eccentric cleavage from (3 R,3′ R)-zeaxanthin which is the principal carotenoid in koayu. (3 R,3′ R)-Astaxanthin was reductively metabolized to (3 S,3' S)-zeaxanthin and finally converted to a new apocarotenoid (3 S)-galloxanthin.