CAROTENOID PIGMENTS IN FISH-I

Little information has been available on carotenoids of goldfish and fancy colored carp, except a paper by Lederer (1935) reporting the occurrence of astacene, xanthophyll (lutein) and carotene in common goldfish. His work, however, still seems to require further confirmation. The results of the present experiments were as follows. 1. Alumina column chromatography of goldfish oil, without saponification, did not show satisfactory separation of the component carotenoids, probably because their positions on the column were affected to a great extent by their forms of esterification with fatty acids. 2. Detailed fractionation of the unsaponifiable matter of goldfish by alumina column chromatography indicated that the carotenoids of the sample consist of two dominant ones; lutein and an astacene-like red carotenoid. The former obtained in a crystalline form with m. p. 175°C, which was lower than that found in STRAIN'S data, was identical with lutein crystal from other sources such as spinach, ginkgo leaves and carrot. The latter, though closely resembles astacene, was supposed to be different since the absorption maximum and the shape of the spectrum were not identical with astacene prepared from the unsaponifiable matter of pink salmon. The authors suggest that this astacene-like substance may be a new one with α-carotene skeleton instead of the well known astacene β-carotene skeleton. This suggestion may be supported by the fact that the new carotenoid shows absorption maximum shifted to the shorter wave-length by 4-10mμ than that of astacene, in accordance with the general rule known between pairs of carotenoids of similar structure with slight difference in possessing either α-or β-ionone rings. The wide zone of red pigment just below the deep red zone of the new pigment on the column of chromatography may be a homologue of intermediate substances between lutein and the new carotenoid. 3. Formulas were proposed for calculation of lutein and the red carotenoid from the data on their mixture. Using the formulas and checking the results when necessary, contents of both carotenoids in goldfish in their various stages of color development were determined. 4. Carotenoids of fancy colored carp seemed similar to that of goldfish. Contents of the two carotenoids were determined on some varieties of the carp.