Astaxanthin → meso-Astaxanthin

Participants

Reaction Steps

A total of 40 preparative injections were processed using 84 L of mobile phase. Thirty-six (36) L of effluent were collected among the five fractions. The preparative system was flushed with 100 mL of methylene chloride approximately every 6–8 injections or whenever the chromatographic separation deteriorated due to effects from mixing with mobile phase in the pump heads during the injection process. Purified materials were recovered by removing the solvents in a rotary evaporator protected from light to afford 25.4 g of 3R, 3′R ester, 47.8 g of meso-(3R, 3′S) ester, and 24.9 g of 3S, 3′S ester. The purified astaxanthin dicamphanate esters were saponified to afford 8.5 g (79.8% purity by HPLC) of 3R, 3′R-astaxanthin, 18.2 g (90.1% purity by HPLC) of meso-astaxanthin, and 9.4 g (82.0% purity by HPLC) of 3S, 3′S-astaxanthin. The major impurities of the saponification reaction were the 13- and 9-cis isomers of astaxanthin, identified by HPLC. The cis-isomers were thermally isomerized to all-trans by refluxing in heptane to afford 8.5 g (87.3% purity by HPLC) of 3R, 3′R-astaxanthin, 18.2 g (92.5% purity by HPLC) of meso-astaxanthin, and 9.4 g (86.8% purity by HPLC) of 3S, 3′S-astaxanthin.

Provenance & Evidence