title: Inhibitors of sterol synthesis: synthesis and spectral properties of derivatives of 3 beta-hydroxy-25,26,26,26,27,27,27-heptafluoro-5 alpha-cholest-8(14)-en-15-one fluorinated at carbon 7 or carbon 9 and their effects on 3-hydroxy-3-methylglutaryl coenzyme A reductase activity in cultured mammalian cells.
abstract: As part of a program to prepare delta 8(14)-15-ketosterols that cannot readily be metabolized to cholesterol or side-chain oxygenated species, we have prepared 3 beta-hydroxy-7 alpha-fluoro-5 alpha-cholest-8(14)-en-15-one (VII) and the 9 alpha-hydroxy (IV), 9 alpha-fluoro (VI) and 7 alpha-fluoro (VIII) derivatives of 3 beta-hydroxy-25,26,26,26,27,27,27-heptafluoro-5 alpha-cholest-8(14)-en-15-one (II). Sterol IV was prepared by oxidation of the delta 8,14 dienol ethyl ether of the 3 beta-acetate of II with m-chloroperbenzoic acid, followed by mild alkaline hydrolysis of the 3 beta-acetate derivative of IV. Treatment of IV with hydrogen fluoride-pyridine gave VI. The 7 alpha-fluoro-15-ketosterols VII and VIII were synthesized by treating the 3 beta,15-bis-trimethylsilyl delta 7,14-dienol ether derivative of the appropriate delta 8(14)-15-ketosterol with N-fluoropyridinium triflate, followed by hydrolysis of residual trimethylsilyl ethers and purification by high-performance liquid chromatography. The combined results of 1H and 13C nuclear magnetic resonance (NMR) chemical shifts, 1H-1H coupling constants, 1H-19F long-range coupling constants and molecular modeling indicated that a 7 alpha-fluoro, 9 alpha-fluoro or 9 alpha-hydroxy substituent has negligible effect on the conformation of the 15-ketosterols. 1H and 13C-NMR data are also given for delta 6,8(14)- and delta 8(14),9(11)-15-ketosterols, synthetic byproducts that could not be detected readily in samples of the fluoro-15-ketosterols by chromatographic methods. Mass spectra of VI and of previously reported 9 alpha-fluoro and 9 alpha-hydroxy-delta 8(14)-15-ketosterols showed abundant M-62 or M-60 ions that appear to correspond to loss of ketene and HF or H2O. The 9 alpha-hydroxy-F7-15-ketosterol IV, the 7 alpha-fluoro-15-ketosterol VII and the 7 alpha-fluoro-F7-15-ketosterol VIII were of equivalent potency to the parent 3 beta-hydroxy-5 alpha-cholest-8(14)-en-15-one (I) in lowering the levels of 3-hydroxy-3-methylglutaryl coenzyme A reductase activity in CHO-K1 cells. The 9 alpha-fluoro-F7-15-ketosterol VI showed high potency but appeared to be slightly less active than I.
authors.affiliation: Department of Biochemistry, Rice University, Houston, TX 77251-1892.
authors.forename: A U
authors.initials: AU
authors.lastname: Siddiqui
authors.forename: S
authors.initials: S
authors.lastname: Swaminathan
authors.forename: F D
authors.initials: FD
authors.lastname: Pinkerton
authors.forename: N
authors.initials: N
authors.lastname: Gerst
authors.forename: W K
authors.initials: WK
authors.lastname: Wilson
authors.forename: H
authors.initials: H
authors.lastname: Choi
authors.forename: G J
authors.initials: GJ
authors.lastname: Schroephfer
mesh_terms: D000818:Animals; D016466:CHO Cells; D002244:Carbon / Q000737:chemistry; D002783:Cholestenones / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D006224:Cricetinae; D005461:Fluorine / Q000737:chemistry; D008401:Gas Chromatography-Mass Spectrometry; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D005466:Fluorocarbons
chemical_list: D002244:Carbon; D002783:Cholestenones; D005461:Fluorine; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; C084394:3-hydroxy-25,26,26,26,27,27,27-heptafluoro-5-cholest-8(14)-en-15-one; D005466:Fluorocarbons