Chemical Synthesis of Astaxanthin n-Octanoic Acid Monoester and Diester and Evaluation of Their Oral Absorbability

We chemically synthesized astaxanthin n-octanoic acid monoester and diester from free astaxanthin and n-octanoic acid by a dehydration reagent in 32 and 22% yield, respectively. The oral absorbability of the n-octanoic acid monoester and diester was evaluated by examining the plasma and liver concentrations of astaxanthin after oral administration of the compounds. The monoester significantly increased the plasma and liver concentration of astaxanthin compared with the long-chain fatty acid ester mixture derived from Haematococcus algae. The diester is inclined to increase it although it is not significant. It is possible that medium-chain fatty acid esters give better oral-absorbability of astaxanthin than long-chain fatty acid esters.