We sought to determine whether the biliary excretion of biotin and biotin metabolites contributes importantly to the overall excretion of the vitamin in mammals, and hence, whether metabolism by gut microorganisms could account for some metabolism of biotin. [14C]Carbonyl-labeled biotin (158 pmol/g body weight) was injected i.v. into six rats; bile and urine were collected in timed intervals for 24 h after injection. Biotin, bisnorbiotin (BNB), biotin-d,l-sulfoxide (BSO), bisnorbiotin methyl ketone (BNBMK), and two unidentified compounds (designated A and B) were quantitated in bile and urine using HPLC/radiometric flow detection. For these six compounds totaled, 1.9 ± 0.2% of the administered 14C was found in bile and 60.6 ± 4.1% in urine. Biotin per se accounted for ∼one-half of the excretion in bile and urine. In bile, BNBMK (11% of total biliary 14C), the unknown compound A (9%), and compound B (25%) were quantitatively the most abundant metabolites. In urine, BNB (24% of total urinary 14C) and BSO (14%) were the most abundant metabolites. The biliary excretion of biotin and metabolites decreased rapidly; 6 h after biotin injection, 14C was not detectable in bile any more. The urinary excretion of BNB, BNBMK, and compounds A and B, however, remained on a constant level during the first 6 h after biotin administration and decreased thereafter. These data provide evidence that the biliary excretion of biotin and metabolites is a quantitatively negligible route of excretion, and we conclude that enteric metabolism of parenteral biotin is unlikely.
|Original language||English (US)|
|State||Published - 1997|
ASJC Scopus subject areas
- Molecular Biology