Tissue distribution of astaxanthin in rats following exposure to graded levels in the feed.

To determine the organ distribution of high doses of astaxanthin in rats (Rattus norvegicus) after oral application, a two week experiment was conducted, observing time (one and two weeks) and dose response (0.3, 1 and 3% of the feed). Low astaxanthin concentrations were detected in the viscera, distributed in a wide range, and not increasing from 7th to 14th day. This indicates that there was rapid elimination or catabolism and no profound long term storage. Liver concentration was unexpectedly low while the highest concentrations were found in spleen, kidneys and adrenals. The main site of astaxanthin accumulation, indeed, was the hairless skin of the tail, this was associated with red coloration (+a(*) in the CIELAB tristimulus). Because the discoloration was not observed until the second week and the variability in the astaxanthin concentrations was lower, it seems that the accumulation and elimination in skin is slower, compared to other tissues. Potential adverse effects such as lesions in the kidneys of three animals and a slight (n.s.) change in the leucogram were also noted. Furthermore, astaxanthin accumulated in the eyes in the same magnitude as it is known for canthaxanthin in the eyes of rats.