Astaxanthin Synonyms: 3,3 '- dihydroxy-beta, beta-carotene 4,4' - dione Molecular structure: Molecular formula: C40H52O4 Molecular Weight: 596.85 CAS registry number: 472-61-7 Content:: NLT2% Characteristics: purple powder Water-soluble: insoluble in water, soluble in most organic solvents. Usage:Astaxanthin is a highly potent antioxidant carotenoid found in seafood and algae that protects lipids from peroxidation.