Astaxanthin

Astaxanthin is a red-orange carotenoid pigment produced by some algae, yeasts, and bacteria and accumulated by animals such as salmon and shrimp. Its extended conjugated structure gives it color and antioxidant activity.

Carotenoids: Carotenoids are lipid-soluble pigments with conjugated carbon chains, found in photosynthetic organisms and many animals. Astaxanthin belongs to this pigment family, whose shared structure absorbs visible light.
Haematococcus pluvialis: Haematococcus pluvialis is a freshwater green microalga that accumulates astaxanthin under environmental stress. This alga is a major natural source used to produce astaxanthin commercially.
Aquaculture: Aquaculture is the farming of aquatic organisms, including fish, shellfish, and algae. Astaxanthin is added to some farmed-fish feeds to provide flesh color and dietary pigment.
Beta-Carotene: Beta-carotene is an orange carotenoid that can be converted into vitamin A in humans. Unlike beta-carotene, astaxanthin is an oxygenated carotenoid and is not a vitamin A precursor.
Conjugated system: A conjugated system has alternating single and multiple bonds that allow electrons to spread across a molecule. Astaxanthin’s extended conjugation absorbs blue-green wavelengths, producing its red-orange appearance.
Xanthophyllomyces dendrorhous: Xanthophyllomyces dendrorhous is a yeast species that produces astaxanthin and other carotenoid pigments. Its fermentation offers a microbial route to astaxanthin apart from algal cultivation.
Fish feed: Fish feed is formulated food supplied to farmed fish to meet nutritional and production needs. Adding astaxanthin can color salmonid flesh and support pigmentation in farmed fish.
Lutein: Lutein is a yellow xanthophyll found in leafy plants and concentrated in the human retina. Both are xanthophylls, but lutein’s structure and common biological roles differ from astaxanthin’s.
Xanthophyll: A xanthophyll is an oxygen-containing carotenoid pigment. Astaxanthin is a xanthophyll, distinguished by hydroxyl and keto groups at both ends.
Carotenoid biosynthesis: Carotenoid biosynthesis is the set of cellular pathways that build carotenoid pigments from isoprenoid precursors. These pathways explain how organisms synthesize astaxanthin from simpler metabolic building blocks.

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FucoxanthinCompared with: Its red color and biological sources contrast with fucoxanthin’s brown-algal association.