Analysis of astaxanthin, adoniurbin, and adonixanthin concentration in human serum

The astaxanthin, adonirubin and adonixanthin (Fig. 2) concentration in human serum were analyzed by the method described by Fukuda et al.⁽²⁵⁾ A 1 ml of water and a 1 ml of ethanol, containing 0.85 µg of β-apo-8'-carotenal (internal standard) and 50 µg of 2,6-dibuthylhydroxytoluene, was added to 300 µl of serum. Then, 5 ml of hexane was added to the mixture and was shaken for 20 min. Then the hexane layer was taken in another test tube after centrifugation [4°C, 3,000 rpm (1,464 × g), 10 min] and was dried over under nitrogen gas flow. The residue was dissolved in 100 µl of chloroform/ethanol and subjected to UPLC-MS/MS analysis using Cadenza CD-C18 column with mixture of 85% acetonitrile in 2 mM ammonium acetate and acetonitrile/methanol/tetrahydrofuran (60:38:2) in 2 mM ammonium acetate as solvent. Detection and quantification were performed by selective reaction monitoring (SRM) of protonated molecule (MH+) of astaxanthin, adonirubin, and adonixanthin.

Structural formula of astaxanthin, adonirubin and adonixanthin.