3'-Oxolutein, a metabolite of lutein in chickens

3'-Oxolutein (3-hydroxy-3'-oxo-beta,epsilon-carotene) was isolated using high performance liquid chromatography (HPLC) from the tissues and egg yolks of chicken fed a diet high in lutein and free of detectable 3'-oxolutein. It was identified by HPLC retention time, absorption spectrum identical to lutein and its esters, disappearance under alkaline conditions without giving rise to lutein, formation of an alkali labile palmitate, formation of a 2,4-dinitrophenylhydrazone, and reduction to lutein from which the dipalmitate was prepared. In each instance the isolated compound behaved identically with authentic 3'-oxolutein prepared by nickel peroxide oxidation of lutein. The order of ratios of lutein to 3'-oxolutein in the various tissues from laboratory and field birds was, in general, intestinal contents greater than intestinal mucosa greater than serum greater than liver approximately toe web approximately egg yolk greater than bile. This order was consistent with the hypothesis that lutein was oxidized to 3'-oxolutein in the liver, which, at least in part, was excreted via the bile into the intestinal lumen where it was diluted with dietary lutein. The remainder of the 3'-oxolutein formed in the liver presumably went into the serum where it was transported to depot sites. The ratio of lutein to 3'-oxolutein in the toe webs of broilers varied with their diet and pigmentation status. Amounts of 3'-oxolutein were found in quail and turkey egg yolks. This previously unreported lutein oxidative capability of liver extends the previously known metabolic acylation and deacylation reactions in poultry.