- Inhibitors of sterol synthesis. Effects of fluorine substitution at carbon atom 25 of cholesterol on its spectral and chromatographic properties and on 3-hydroxy-3-methylglutaryl coenzyme a reductase activity in CHO-K1 cells
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25-Fluorocholesterol (III) was prepared by treatment of 25-hydroxycholesterol (IV) with hydrogen fluoride-pyridine. Compounds III, IV, and cholesterol (I) were fully characterized by 1H and 13C NMR, and stereochemical assignments were established for the C-22 and C-23 protons. The side-chain proton assignments, which apply to most other sterols with a saturated eight-carbon side chain, were based on conformational analysis and comparison with NMR data for 25,26,26,26,27,27,27-heptafluorocholesterol (II). The chromatographic behavior of I, II, and III were compared on thin-layer chromatography, high performance liquid chromatography, and gas chromatography. Major fragment ions in electron-impact mass spectra of III were analogous to ions of either cholesterol or desmosterol, and a similar analogy was observed for the trimethylsilyl ethers. The 25-hydroxysterol IV and the 25-fluorosterol III differed markedly in their effects on the levels of 3-hydroxy-3-methylglutaryl coenzyme A reductase activity in CHO-K1 cells. Whereas 25-hydroxycholesterol caused a ~66% lowering of reductase activity in cells at 0.1 ·M, the 25-fluorosterol III had no effect at this concentration.
- Wilson, William K.,Swaminathan, Shankar,Pinkerton, Frederick D.,Gerst, Nicolas,Schroepfer Jr., George J.
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- SIDE CHAIN MODIFIED STEROLS AS PROBES INTO INSECT MOLTING HORMONE METABOLISM. II: SYNTHESIS OF MONOFLUOROCHOLESTEROLS
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The hydroxylations of the cholesterol side chain at C-20, 22, and 25 are key terminal events in ecdysone biogenesis. We have prepared the C-20, C-22, C-24, and C-25 monofluorinated cholesterols as potential inhibitors of these hydroxylation events, and preliminary bioassay results in Manduca sexta are reported.The synthesis of -20-fluorocholesterol is also described.Although the 20-, 22-, and 25-monofluorocholesterols do not appear to affect larval growth and development, the 24-fluoro isomer shows a moderate retardation of growth and a modest increase in mortality.
- Prestwich, Glenn D.,Shieh, Hong Ming,Gayen, Apurba K.
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- Blocked cholecalciferol and dihydrotachysterol 3 derivatives
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Novel cholecalciferol and dihydrotachysterol3 derivatives produced against metabolic conversions at the 25-position, their preparation, pharmaceutical compositions, methods of treating steroid-induced osteoporosis, senile osteoporosis and secondary hyperparathyroidism, especially that induced by an insufficient amount of calcium in relationship to the amount of phosphate, novel intermediates and their preparation are disclosed.
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