TUNAXANTHIN - OCCURRENCE AND ABSOLUTE STEREOCHEMISTRY

1. 1. Three stereoisomeric carotenoids, IIIb, IVb and Vb, of the 3,3′-dihydroxy-ε{lunate},ε{lunate}-carotene (tunaxanthin) constitution were identified from the skin of the Southern California fish, Oxyjulis californica; all three possess the unexpected 6S,6′S stereochemistry. 2. 2. One of these (Vb) was the enantiomer of chiriquixanthin A (Va) and another (IIIb) of chiriquixanthin B (IIIa) which had been isolated from the skin of the yellow Costa Rican frog, Atelopus chiriquiensis. 3. 3. The major carotenoid pigment from Sebastes flavidus is the tunaxanthin stereoisomer identical to chiriquixanthin B (IIIa). 4. 4. The natural occurrence in fishes of these epimeric and enantiomeric carotenoid pigments, which are unknown in plants, is quite remarkable and provides a powerful means of investigating metabolic transformations of carotenoids. © 1979.