Inhibitors of sterol synthesis. Chemical synthesis and spectral properties of 3 beta-hydroxy-5 alpha-cholesta-8(14),24-dien-15-one, 3 beta,25-dihydroxy-5 alpha-cholest-8(14)-en-15-one, and 3 beta,24-dihydroxy-5 alpha-cholest-8(14)-en-15-one and their effects on 3-hydroxy-3-methylglutaryl coenzyme A reductase activity in CHO-K1 cells.
Side-chain functionalized delta 8(14)-15-ketosterols have been synthesized from 3 beta-acetoxy-24-hydroxy-5 alpha-chol-8(14)-en-15-one (VI) as part of a program to prepare potential metabolites and analogs of 3 beta-hydroxy-5 alpha-cholest-8(14)-en-15-one (I), a potent regulator of cholesterol metabolism. Oxidation of VI to the 24-aldehyde VII, followed by Wittig olefination with isopropyltriphenylphosphonium iodide gave 3 beta-acetoxy-5 alpha-cholesta-8(14),24-dien-15-one (VIII), which was hydrolyzed to the free sterol IX. Oxymercuration of VIII followed by hydrolysis of the 3 beta-acetate gave 3 beta,25-dihydroxy-5 alpha-cholest-8(14)-en-15-one (IV). Hydroboration-oxidation of VIII followed by hydrolysis of the 3 beta-acetate gave 3 beta,24-dihydroxy-5 alpha-cholest-8(14)-en-15-one (V) as a 5:4 mixture of the 24R and 24S epimers. 1H and 13C nuclear magnetic resonance (NMR) assignments and mass spectral fragmentation patterns, supported by high-resolution measurements, are presented for IV and its 3 beta-acetate, V, VII, VIII, and IX. Characterization of IV by NMR and of trimethylsilyl ethers of IV and V by gas chromatography-mass spectrometry was compatible with spectral data for samples of IV and V isolated previously after incubation of I with rat liver mitochondria in the presence of NADPH. Sterols IV, V, and IX were very potent in lowering of the level of 3-hydroxy-3-methylglutaryl coenzyme A reductase activity in Chinese hamster ovary cells; their potency was comparable to that of I.
Swaminathan
S
S
Department of Biochemistry, Rice University, Houston, TX 77251.
Pinkerton
F D
FD
Numazawa
S
S
Wilson
W K
WK
Schroepfer
G J
GJ
D000818:Animals; D016466:CHO Cells; D002783:Cholestenones / Q000138:chemical synthesis* / Q000494:pharmacology*; D006224:Cricetinae; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D013261:Sterols / Q000096:biosynthesis*
D002783:Cholestenones; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D013261:Sterols; C078005:3,24-dihydroxycholest-8(14)-en-15-one; C073202:3,25-dihydroxycholest-8(14)-en-15-one; C078004:3-hydroxycholest-8(14),24-dien-15-one