Katharina Schiedt

Carotenoids in diets for salmonids: I. Pigmentation of rainbow trout with the individual optical isomers of astaxanthin in comparison with canthaxanthin

Abstract Visual and chemical determinations revealed that the individual optical isomers of astaxanthin were more efficacious than canthaxanthin in pigmenting the flesh of rainbow trout ( Salmo gairdneri , Richardson). The visual assessment of the astaxanthin pigmentation by means of a colour scale correlated well with the chemical determination. The same utilization was found for all three astaxanthin isomers, ( 3S, 3′S )-, ( 3R, 3′S )-, ( 3R, 3′R )-astaxanthin and a 1 : 2 : 1 mixture of the three isomers. No epimerization took place at the chiral centres of C-3 and C-3′ in astaxanthin. Astaxanthin and canthaxanthin were not interconverted. No metabolites were detected in the flesh.

Carotenoids in diets for salmonids: IV. Pigmentation of Atlantic salmon with astaxanthin, astaxanthin dipalmitate and canthaxanthin

Abstract Diets supplemented with synthetic astaxanthin, astaxanthin dipalmitate and canthaxanthin at concentrations of 0, 30, 60 and 90 mg/kg, as carotenoid equivalents, were fed to groups of Atlantic salmon (Salmo salar L.) for 56 weeks. The mean initial and final fish weights were 62 and 406 g respectively. There was a tendency for astaxanthin to be more efficiently utilized than canthaxanthin, which in turn was more efficiently utilized than astaxanthin dipalmitate, for flesh pigmentation. These differences were partly explained by differences in the apparent digestibility of the carotenoids. The flesh pigmentation increased with increasing dietary carotenoid concentration. The visual assessments of flesh colour by means of a colour scale correlated well with the chemical determination. The carotenoid content of the skin was higher for the fish fed diets containing carotenoids than for the control groups, but there was no significant difference in the carotenoid concentration in the skin of the fish fed the different carotenoids.

Astaxanthin and its metabolites in wild rainbow trout (Salmo gairdneri R.)

Abstract 1. 1. The unusual intensely red exterior pigmentation of four wild rainbow trout, caught in an alpine lake of Austria, prompted quantitative and qualitative analysis of carotenoids in skin and flesh. 2. 2. Emphasis was laid on the absolute configuration of the hydroxycarotenoids. 3. 3. (3S,3′S- Astaxanthin was the main pigment in skin and flesh besides some yellow xanthophylls, which in skin were β-adonixanthin, (3R,3′S,6′R)- epilutein and (3R,3′R)- zeaxanthin and in flesh, lutein and zeaxanthin. 4. 4. The results are compared with data obtained in farmed rainbow trout fed unlabelled and tritiated astaxanthin enantiomers. 5. 5. The vitamin A1 (retinol) and A2 (dehydroretinol) statuses in liver were determined.

New Aspects of Carotenoid Metabolism in Animals

This review will present not only our own recent results, but also the achievements in the biochemistry of animal carotenoids during the past three years in general.

[15] Metabolism of carotenoids and in Vivo racemization of (3S,3′S)-Astaxanthin in the crustacean Penaeus

Publisher Summary In the shrimp Penaeus of the order Decapoda, as in most crustaceans, astaxanthin is the major carotenoid accumulated in the carapace. In the living animal, astaxanthin is bound noncovalently to a protein in a stoichiometric ratio. The carotenoprotein is water-soluble and may vary in color from blue to green to brown. This chapter discusses the in vivo racemization of optically active (3S,3′S )-[15,15′-3H2]astaxanthin in Penaeus japonicus. The fact that crustaxanthin and tetrahydroxypirardixanthin, the proposed reduction products of astaxanthin, were not labeled does not necessarily prove that these compounds are not involved in the metabolism of astaxanthin in Penaeus. Only one-fourth of the astaxanthin in the body was labeled and absorbed during the experimental period. The bulk of astaxanthin must have been biosynthesized or absorbed during the preexperimental period. Various systems of adsorption and reversed-phase chromatography on columns, thin layer chromatography, and high-performance liquid chromatography were used for the separation of the different carotenoids. The yellow carotenoids, such as isoastaxanthin and the tetrols, were acetylated immediately after saponification to improve their stability.

Metabolism of carotenoids in salmonids—I. idoxanthin, a metabolite of astaxanthin in the flesh of atlantic salmon (Salmon salar, L.) under varying external conditions

Abstract 1. 1. Idoxanthin (3,3′,4′-trihydroxy-β,β-caroten-4-one) was found to be a metabolite of astaxanthin (3,3′-di-hydorxy-β,β-carotene-4,4′-dione) in Atlantic salmon. Idoxanthin was characterized by TLC, HPLC, VIS 1 H-NMR and MS. 2. 2. In experimental fish reared indoors in tanks, an increased formation and deposition of this metabolite in flesh was noticed, presumably as a result of stress. 3. 3. In farmed salmon kept in net cages in the open sea, idoxanthin was also found after one year of pigmentation, but had disappeared completely after two years when the fish had reached market size. 4. 4. Only minute amounts of idoxanthin were found in the flesh of wild Atlantic salmon comparable weights. 5. 5. Cofigurational and biochemical aspects of idoxanthin formation are discussed.