Dose response in uptake and deposition of intraperitoneally administered astaxanthin in Atlantic salmon (Salmo salar L.) and Atlantic cod (Gadus morhua L.)

Doses of 12.5, 25 or 50 mg astaxanthin (Lucantin Pink, 10% astaxanthin; BASF, Germany) were dispersed in phosphate buffered saline solution and injected into the abdominal cavity of duplicated groups of Atlantic salmon (Salmo salar; 370 g) and Atlantic cod (Gadus morhua; 210 g) to determine the dose-response relationships for astaxanthin E/Z-isomers and the metabolite idoxanthin in plasma, muscle, liver, kidney and skin, in fish species that usually have white or red flesh. The control fish groups of both species were injected with astaxanthin in phosphate buffered saline solution. Following injection the fish were fed a diet with 10 mg astaxanthin kg− 1 of which 84% was the all-E-isomer, 6.7% the 9Z and 9.3% the 13Z-isomer, respectively. Astaxanthin concentrations increased linearly in a dose-dependent manner in plasma and muscle of both species (P < 0.0001), and were highly correlated (P < 0.0001). Concentrations up to 90 and 50 mg astaxanthin l− 1 in plasma and 30 and 1 mg astaxanthin kg− 1 in muscle were detected in Atlantic salmon and cod, respectively. Unsaturated binding capacity was indicated by the linear dose-response of muscle astaxanthin. Astaxanthin E/Z isomer accumulation in the various tissues was selective. A selective accumulation of astaxanthin Z-isomers, and in particular the 13Z-isomer, in plasma, muscle and liver was found in Atlantic salmon and Atlantic cod injected with astaxanthin compared to control fish (P < 0.0001). No mortality, but a reduction in growth was evident by increasing doses. Higher astaxanthin concentrations in plasma, muscle, skin, kidney and liver of Atlantic salmon and Atlantic cod may thus be obtained by intraperitoneal injection than by regular feeding. Cellular incorporation mechanisms in the muscle apparently explain the differences in astaxanthin uptake in the muscle of these fish species.