Effect of administration route and dose on metabolism of nine bioselenocompounds.

The nutritional availability of selenium (Se) is highly dependent on its chemical form because chemical form affects absorption, distribution, metabolism, and excretion. We evaluated the effects of administration route and dose on the bioavailability of nine Se compounds found in biota, the so-called bioselenocompounds, such as selenite, selenate, selenocyanate (SeCN), Se-methylselenocysteine (MeSeCys), selenomethionine (SeMet), selenohomolanthionine (SeHLan), selenocystine (SeCys2), 1β-methylseleno-N-acetyl-d-galactosamine (SeSug1), and trimethylselenonium ion (TMSe). We determined the bioavailability of bioselenocompounds recovered as urinary selenometabolites and serum selenoproteins from urine and serum of Se-deficient rats after the administration of bioselenocompounds by speciation analysis. Urinary Se was more easily recovered than serum selenoproteins, suggesting that the speciation of urinary Se is a better tool to indicate Se status in the body. The intravenous administration of bioselenocompounds showed different Se bioavailability from the oral administration. Intestinal microflora might be involved in the bioavailability of some bioselenocompounds, such as SeCN, MeSeCys, and SeSug1.