An overview of astaxanthin determination in marine biological samples

Abstract

Astaxanthin (AX) (3,3’dyhydroxy-β,β-carotene-4,4´dione) is a pigment that belongs to the family of the xanthophylls, the oxygenated derivatives of carotenoids whose synthesis in plants derives from ly- copene. AX, which may not be synthesized de novo by animals, is one of the main pigments in marine ecosystems found in crustacean, and many fish species. In pelagic marine food webs, copepods are the main producers of AX, being also the principal components of Antarctic Krill pigment. Thus, in the aquaculture industry AX is present in feed formulations for salmonids and other farmed fish species, where represent an important cost of the feeds. Depending in their origin, AX can be found in association with other compounds. It may be sterified in one or both hydroxyl groups with different fatty acids such as palmitic, oleic, estearic, or linoleic. It may also be found free, that is, with the hydroxyl groups without sterification; or else, forming a chemical complex with proteins (carotenoproteins) or lipoproteins (carotenolipoproteins). Synthetic AX is not sterified while found in algae is always sterified. AX has an enormous commercial and industrial prospect. Therefore, due the growing demand for natural foods has been stimulated the search for natural sources of AX with potential for industrialization like microalgae, shrimp, krill, crab and langostilla between them. In the aquaculture context, the use of AX for the feeding industry is important not only from the standpoint of pigmentation to increase con- sumer acceptance but also as a necessary nutrient for adequate growth and reproduction of commercially valuable species. Therefore, the accurate determination of AX forms in this kind of biological matrices is necessary which involves extraction prior to their determination. In this work, a review of the reported methods for the analysis of AX in marine organisms implied in the aquaculture industry (microalgae, shrimps, crabs and fishes) which are always based on Liquid Chromatography (LC) coupled to different detectors like diode array (DAD) and mass spectrometry (MS) was done. At the same time different extraction and clean-up techniques currently employed are discussed.