Astaxanthin

Astaxanthin /æstəˈzænθɪn/ is a keto-carotenoid. It belongs to a larger class of chemical compounds known as terpenes (as a tetraterpenoid) built from five carbon precursors, isopentenyl diphosphate, and dimethylallyl diphosphate. Astaxanthin is classified as a xanthophyll (originally derived from a word meaning 'yellow leaves' since yellow plant leaf pigments were the first recognized of the xanthophyll family of carotenoids), but currently employed to describe carotenoid compounds that have oxygen-containing components, hydroxyl (-OH) or ketone (C=O), such as zeaxanthin and canthaxanthin. Indeed, astaxanthin is a metabolite of zeaxanthin and/or canthaxanthin, containing both hydroxyl and ketone functional groups. Astaxanthin /æstəˈzænθɪn/ is a keto-carotenoid. It belongs to a larger class of chemical compounds known as terpenes (as a tetraterpenoid) built from five carbon precursors, isopentenyl diphosphate, and dimethylallyl diphosphate. Astaxanthin is classified as a xanthophyll (originally derived from a word meaning 'yellow leaves' since yellow plant leaf pigments were the first recognized of the xanthophyll family of carotenoids), but currently employed to describe carotenoid compounds that have oxygen-containing components, hydroxyl (-OH) or ketone (C=O), such as zeaxanthin and canthaxanthin. Indeed, astaxanthin is a metabolite of zeaxanthin and/or canthaxanthin, containing both hydroxyl and ketone functional groups. Like many carotenoids, astaxanthin is a lipid-soluble pigment. Its red-orange colour is due to the extended chain of conjugated (alternating double and single) double bonds at the centre of the compound. This chain of conjugated double bonds is also responsible for the antioxidant function of astaxanthin (as well as other carotenoids) as it results in a region of decentralized electrons that can be donated to reduce a reactive oxidizing molecule. Astaxanthin is a blood-red pigment and naturally originates in the rainwater microalgae (Haematococcus pluvialis) and the yeast fungus called Xanthophyllomyces dendrorhous (also known as Phaffia). The algae undergoes a stressing via one or a combination of conditions ranging from the lack of nutrients, increased salinity, and excessive sunshine to create Astaxanthin. The species that consume this stressed freshwater microalgae—salmon, red trout, red sea bream, flamingo, crustaceans (shrimp, krill, crab, lobster and crayfish)—reflect the pigmentation of the red-orange hues in their appearances. The structure of astaxanthin by synthesis was described in 1975. Astaxanthin is not converted to vitamin A in the human body so it is completely nontoxic if given orally. Astaxanthin can also be used as a dietary supplement intended for human, animal, and aquaculture consumption. The industrial production of astaxanthin comes from plant- or animal-based and synthetic sources. The U.S. Food and Drug Administration has approved astaxanthin as a food coloring (or color additive) for specific uses in animal and fish foods. The European Commission considers it food dye and it is given the E number E161j. Astaxanthin from algae, synthetic and bacterial sources, is generally recognized as safe (GRAS) by the FDA. As a food color additive astaxanthin and astaxanthin dimethyldisuccinate are restricted for use in Salmonid fish feed only. Astaxanthin is present in most red-coloured aquatic organisms. The content varies from species to species, but also from individual to individual as it is highly dependent on diet and living conditions. Astaxanthin, and other chemically related asta-carotenoids, has also been found in a number of lichen species of the arctic zone.