Plasma appearance of unesterified astaxanthin geometrical E/Z and optical R/S isomers in men given single doses of a mixture of optical 3 and 3′R/S isomers of astaxanthin fatty acyl diesters ☆

Abstract Appearance, pharmacokinetics and distribution of astaxanthin all- E -, 9 Z - and 13 Z -geometrical and (3 R ,3′ R )-, (3 R ,3′ S )- and (3 S ,3′ S )-optical isomers in plasma fractions were studied in three middle-aged male volunteers (41–50 years) after ingestion of a single meal containing first a 10-mg dose equivalent of astaxanthin from astaxanthin diesters, followed by a dose of 100 mg astaxanthin equivalents after 4 weeks. Direct resolution of geometrical isomers and optical isomers of astaxanthin dicamphanates by HPLC after saponification showed that the astaxanthin consisted of 95.2% all- E -, 1.2% 9 Z - and 3.6% 13 Z -astaxanthin, of (3 R ,3′ R )-, (3 R ,3′ S ; meso )- and (3 S ,3′ S )-astaxanthin in a 31:49:20 ratio. The plasma astaxanthin concentration–time curves were measured during 76 h. Astaxanthin esters were not detected in plasma. Maximum levels of astaxanthin ( C max =0.28±0.1 mg/l) were reached 11.5 h after administration and the plasma astaxanthin elimination half-life was 52±40 h. The C max at the low dose was 0.08 mg/l and showed that, the dose response was non-linear. The (3 R ,3′ R )-astaxanthin optical isomer accumulated selectively in plasma compared to the (3 R ,3′ S )- and (3 S ,3′ S )-isomers, and comprised 54% of total astaxanthin in the blood and only 31% of total astaxanthin in the administered dose. The astaxanthin Z -isomers were absorbed selectively into plasma and comprised ∼32% of total astaxanthin 6–7.5 h postprandially. The proportion of all- E -astaxanthin was significantly higher in the very low density lipoproteins and chylomicrons (VLDL/CM) plasma lipoprotein fraction than in the high density lipoproteins (HDL) and low denisty lipoproteins (LDL) fractions ( P Z -isomers compared to the all- E -astaxanthin before uptake in blood and that the astaxanthin esters are hydrolyzed selectively during absorption.