Carotenoids in the sea urchin Paracentrotus lividus

摘要

The roe of the edible sea urchin Paracentrotus lividus is commercially valuable and highly prized in the sushi market. However, roe colour varies with season, the urchin's nutritional state, its state of maturity and its sex. This study has characterised the carotenoid pigment profile of the gonads and gut wall of wild P. lividus using a combination of reversed-phase diode-array HPLC and LC-MS. The major pigments occurring in the gut wall are breakdown products of fucoxanthin, namely fucoxanthinol and amarouciaxanthin A. Lower levels of echinenone, lutein, isozeaxanthin and beta -caro-tene are also present. The gut wall of the female urchins contains pigments not present in the males, indicating additional metabolism in the former. It is clear that the gut wall is a major site of carotenoid metabolism. Male and female gonads have a broadly similar pigment profile with echinenone accounting for between 70-80% of the total carotenoid (c.f. gut: 20%). Both all-trans and 9'-cis forms of beta -echinenone are found in the ratio 1:10 (w/w). The detection of large levels of 9'cis-echinenone in wild P. lividus is unexpected due to the absence of 9'-cis forms of carotenoid in the natural, algal, diet. Amounts of lutein and isozeaxanthin are consistently higher in the female rather than male gonads with levels of these peaking shortly after spawning. The presence of 9'-cis echinenone as the major carotenoid contributing to the pigmentation/colour of the gonad is an important observation in terms of developing artificial diets for urchin cultivation. The implications of this are discussed further.