The carotenoids of crab Paralithodes brevipes (Hanasakigani in Japanese)

The carotenoids in the carapace, flesh and gonad of Paralithodes brevipes were investigated from the stereochemical point of view. The absolute configuration of papilioerythrinone (=3-hydroxy-β, e-carotene-4, 3'-dione) isolated from the crab was determined to be (3S, 6'R)-configuration. In the carapace and flesh, three stereoisomers of astaxanthin (33-39%) and (3S, 3'S)-7, 8-didehydro-astaxanthin (27-32%) were identified as major components accompanied by (3S, 3'S)-7, 8, 7', 8'-tetradehydro-astaxanthin (6-7%), fritschiellaxanthin (4-10%) and papilioerythrinone (2-6%) etc., while in the gonad β, β-carotene (64%) was found to be dominant along with three stereo-isomers of astaxanthin (11%), echinenone (7%) and isocryptoxanthin (3%) etc. From the experimental results obtained, we proposed the plausible oxidative metabolic path-way of lutein A to papilioerythrinone via fritschiellaxanthin in P. brevipes.