title: Synthesis of [3alpha-3H]cholesta-5,8-dien-3beta-ol and tritium-labeled forms of other sterols of potential importance in the Smith-Lemli-Optiz syndrome.
abstract: Five unsaturated sterols relevant to the Smith-Lemli-Opitz syndrome have been prepared in high radiochemical purity with a tritium label at the 3alpha position. Swern oxidation of cholesta-5,8-dien-3beta-ol and other unlabeled C27 sterols afforded the corresponding 3-ketosteroids, and reduction with tritiated NaBH4 gave the desired 3alpha-3H sterols, with double bonds at the delta(5,8), delta(5,8(14)), delta(6,8), delta(6,8(14)), and delta8 positions. High radiochemical purity of the tritiated sterols was demonstrated by normal phase, reversed phase, and silver-ion (Ag+) high-performance liquid chromatography (HPLC). In the course of this work, we developed a medium-pressure variant of Ag+-HPLC for purifying radiolabeled samples, documented significant isotopic fractionation of the 3alpha-tritiated sterols and their acetates on Ag+-HPLC, and discovered unexpected effects of a delta(8(14)) bond on the conformation of 3-keto-delta5-steroids. The synthetic and analytical methodologies described herein should provide a sound basis for investigating the origin and metabolism of sterols involved in the Smith-Lemli-Opitz syndrome and in late stages of cholesterol biosynthesis.
authors.affiliation: Department of Chemistry, Rice University, Houston, TX 77005-1892, USA.
authors.forename: B
authors.initials: B
authors.lastname: Ruan
authors.forename: W K
authors.initials: WK
authors.lastname: Wilson
authors.forename: J
authors.initials: J
authors.lastname: Pang
authors.forename: G J
authors.initials: GJ
authors.lastname: Schroepfer
mesh_terms: D002775:Cholestadienols / Q000138:chemical synthesis* / Q000378:metabolism; D002849:Chromatography, Gas; D002851:Chromatography, High Pressure Liquid; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D011854:Radiochemistry; D019082:Smith-Lemli-Opitz Syndrome / Q000378:metabolism*; D013056:Spectrophotometry, Ultraviolet; D013261:Sterols / Q000138:chemical synthesis* / Q000378:metabolism; D014316:Tritium
chemical_list: D002775:Cholestadienols; D013261:Sterols; D014316:Tritium; C026359:cholesta-5,8-dien-3 beta-ol