Bile acid synthesis in man. II. Determination of 7 α-hydroxycholesterol, (22R)-22-hydroxycholesterol, and 26-hydroxycholesterol in human meconium

Abstract

7 alpha-Hydroxycholesterol, (22R)-22-hydroxycholesterol and 26-hydroxycholesterol have been quantitated in human meconium. The method used tetrahydrofuran for extraction and solvolysis of the sulfate esters, liquid partition chromatography for the separation of the hydroxysterols, gas-liquid chromatography for quantitation, gas-liquid chromatography-mass spectrometry for identification, and tritiated and 14C-labeled tracers for overall recovery standards. (22R)-22-Hydroxycholesterol and 26-hydroxycholesterol were present almost entirely, ( greater than 93%) in the sulfate fraction at concentrations of 3.8-6.4 and 0.4-0.8 mg per 100 g meconium, respectively. Since free tritiated (22R)-22-hydroxycholesterol was used as the tracer to assess recovery of this hydroxysterol, the concentrations found for this compound may be minimal. Tritiated 26-hydroxycholesterol 3,26-disulfate was used as tracer to determine the levels of this compound, and the solvolysis procedure was optimized for recovery of 26-hydroxycholesterol and least decomposition of 7 alpha-hydroxycholesterol. No significant amounts of 7 alpha-hydroxycholesterol were found based on the tracer-free hydroxysterol as recovery standard.