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Parish EJ, Luo C, Boos TL. A new chemical synthesis of 5alpha-cholest-8(14)-en-3beta,5alpha-diol. Chem Phys Lipids 2001; 109:113-5. [PMID: 11163349 DOI: 10.1016/s0009-3084(00)00217-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Reduction of 3beta-benzoyloxy-14alpha,15alpha-epoxy-5alpha-cholest-7-ene with lithium in ethylenediamine gave 5alpha-cholest-8(14)-en-3beta, 5alpha-diol in high yield. This procedure offers an alternate synthesis through the reductive rearrangement of an alpha,beta-unsaturated steroidal epoxide.
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Affiliation(s)
- E J Parish
- Department of Chemistry, Auburn University, Auburn, AL 36849-5312, USA
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Abstract
Oxygenated derivatives of cholesterol (oxysterols) present a remarkably diverse profile of biological activities, including effects on sphingolipid metabolism, platelet aggregation, apoptosis, and protein prenylation. The most notable oxysterol activities center around the regulation of cholesterol homeostasis, which appears to be controlled in part by a complex series of interactions of oxysterol ligands with various receptors, such as the oxysterol binding protein, the cellular nucleic acid binding protein, the sterol regulatory element binding protein, the LXR nuclear orphan receptors, and the low-density lipoprotein receptor. Identification of the endogenous oxysterol ligands and elucidation of their enzymatic origins are topics of active investigation. Except for 24, 25-epoxysterols, most oxysterols arise from cholesterol by autoxidation or by specific microsomal or mitochondrial oxidations, usually involving cytochrome P-450 species. Oxysterols are variously metabolized to esters, bile acids, steroid hormones, cholesterol, or other sterols through pathways that may differ according to the type of cell and mode of experimentation (in vitro, in vivo, cell culture). Reliable measurements of oxysterol levels and activities are hampered by low physiological concentrations (approximately 0.01-0.1 microM plasma) relative to cholesterol (approximately 5,000 microM) and by the susceptibility of cholesterol to autoxidation, which produces artifactual oxysterols that may also have potent activities. Reports describing the occurrence and levels of oxysterols in plasma, low-density lipoproteins, various tissues, and food products include many unrealistic data resulting from inattention to autoxidation and to limitations of the analytical methodology. Because of the widespread lack of appreciation for the technical difficulties involved in oxysterol research, a rigorous evaluation of the chromatographic and spectroscopic methods used in the isolation, characterization, and quantitation of oxysterols has been included. This review comprises a detailed and critical assessment of current knowledge regarding the formation, occurrence, metabolism, regulatory properties, and other activities of oxysterols in mammalian systems.
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Affiliation(s)
- G J Schroepfer
- Departments of Biochemistry, Rice University, Houston, Texas, USA.
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Parish EJ, Tsuda M, Schroepfer GJ. Stereospecific 1,4-addition to an alpha,beta-unsaturated steroidal epoxide: syntheses of new 15-oxygenated sterols. Chem Phys Lipids 1988; 49:119-29. [PMID: 3233707 DOI: 10.1016/0009-3084(88)90073-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
3 beta-Benzoyloxy-14 alpha,15 alpha-epoxy-5 alpha-cholest-7-ene (1) is a key intermediate in the synthesis of C-7 and C-15 oxygenated sterols. Treatment of 1 with benzoyl chloride resulted in the formation of 3 beta,15 alpha-bis-benzoyloxy-7 alpha-chloro-5 alpha-cholest-8(14)-ene (2). Reaction of 2 with LiAlH4 or LiAlD4 resulted in the formation of 5 alpha-cholest-7-ene-3 beta,15 alpha-diol (3a) or [14 alpha-2H]5 alpha-cholest-7-ene-3 beta,15 alpha-diol (3b). Diol 3b was selectively oxidized by Ag2CO3/celite to [14 alpha-2H]5 alpha-cholest-7-en-15 alpha-ol-3-one (4). Treatment of 1 with MeMgI/CuI gave 7 alpha-methyl-5 alpha-cholest-8(14)-ene-3 beta,15 alpha-diol (5). Selective oxidation of 5 with pyridinium chlorochromate (PCC)/pyridine or oxidation with PCC resulted in the formation of 7 alpha-methyl-5 alpha-cholest-8(14)-en-3 beta-ol-15-one (6) and 7 alpha-methyl-5 alpha-cholest-8(14)-ene-3,15-dione, respectively. Reduction of 6 with LiAlH4 yielded 5 and 7 alpha-methyl-5 alpha-cholest-8(14)-ene-3 beta,15 beta-diol (6). Reaction of 1 with benzoic acid/pyridine gave 3 beta,7 alpha-bis-benzoyloxy-5 alpha-cholest-8(14)-en-15 alpha-ol (9). Treatment of 9 with LiAlH4 or ethanolic KOH resulted in the formation of 5 alpha-cholest-8(14)-ene-3 beta,7 alpha,15 alpha-triol (10). Dibenzoate 9, upon brief treatment with mineral acid, gave 3 beta-benzoyloxy-5 alpha-cholest-8(14)-ene-15-one (11). Oxidation of 9 with PCC yielded 3 beta,7 alpha-bis-benzoyloxy-5 alpha-cholest-8(14)-ene-15-one (12). Ketone 12 was also prepared by the selective hydride reduction of 5 alpha-cholest-8(14)-en-7 alpha-ol-3,15-dione (13) to give 5 alpha-cholest-8(14)-ene-3 beta,7 alpha-diol-15-one (14), which was then treated with benzoyl chloride to produce 12.
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Affiliation(s)
- E J Parish
- Department of Biochemistry, Rice University, Houston, TX 77001
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Emmons GT, St Pyrek J, Dam R, Martin M, Kudo K, Schroepfer GJ. 5 alpha-cholest-8(14)-en-3 beta-ol-15-one, a potent regulator of cholesterol metabolism: occurrence in rat skin. J Lipid Res 1988. [DOI: 10.1016/s0022-2275(20)38468-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Monger DJ, Schroepfer GJ. Inhibitors of cholesterol biosynthesis. Further studies of the metabolism of 5 alpha-cholest-8(14)-en-3 beta-ol-15-one in rat liver preparations. Chem Phys Lipids 1988; 47:21-46. [PMID: 3396133 DOI: 10.1016/0009-3084(88)90030-8] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
5 alpha-Cholest-8(14)-en-3 beta-ol-15-one is a potent inhibitor of sterol biosynthesis in mammalian cells in culture and has significant hypocholesterolemic activity upon oral administration to rodents and non-human primates. The conversion of the 15-ketosterol to cholesterol upon incubation with the 10,000 x g supernatant fraction of rat liver homogenate preparations under aerobic conditions has been reported (D.J. Monger, E.J. Parish and G.J. Schroepfer, Jr. (1980) J. Biol. Chem. 255, 11122-11129). Presented herein are results of studies of the metabolism of [2,4-3H]5 alpha-cholest-8(14)-en-3 beta-ol-15-one obtained upon incubation with the microsomal, cytosolic and the 10,000 x g supernatant fractions of liver homogenates of female rats under a variety of conditions. The results of these studies indicated metabolism of the 15-ketosterol to materials with the chromatographic properties of fatty acid esters of the 15-ketosterol, fatty acid esters of C27-monohydroxysterols, a component similar to the 15-ketosterol (possibly an isomer of the delta 8(14)-15-ketosterol), and a polar component. Detailed studies of the C27-monohydroxysterols obtained from incubation of the 15-ketosterol under anaerobic conditions indicated the formation of labeled 5 alpha-cholesta-8,14-dien-3 beta-ol and 5 alpha-cholest-7-en-3 beta-ol which were characterized by their behavior on silicic acid column chromatography, by the behavior of their acetate derivatives on medium pressure liquid chromatography on alumina-AgNO3 columns, and by co-crystallization of the labeled sterols with authentic unlabeled standards. The identification of 5 alpha-cholesta-8,14-dien-3 beta-ol and 5 alpha-cholest-7-en-3 beta-ol as metabolites of the 15-ketesterol, coupled with previous studies of the metabolism of 5 alpha-cholesta-8,14-dien-3 beta-ol and of 5 alpha-cholest-8(14)-ene-3 beta, 15 alpha-diol and 5 alpha-cholest-8(14)-ene-3 beta, 15 beta-diol has permitted the formulation of a scheme for the overall metabolism of the 15-ketosterol to cholesterol.
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Affiliation(s)
- D J Monger
- Department of Biochemistry, Rice University, Houston, TX 77251
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Monger D, Parish E, Schroepfer G. 15-Oxygenated sterols. Enzymatic conversion of [2,4]3H]5 alpha-cholest-8(14)-en-3 beta-ol-15-one to cholesterol in rat liver homogenate preparations. J Biol Chem 1980. [DOI: 10.1016/s0021-9258(19)70264-6] [Citation(s) in RCA: 39] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Pascal R, Schroepfer G. 15-Oxygenated sterols with the unnatural cis-C-D ring junction. Studies of the metabolism of 5 alpha,14 beta-cholest-7-ene-3 beta,15 alpha-diol and 5 alpha,14 beta-cholest-7-ene-3 beta,15 beta-diol. J Biol Chem 1980. [DOI: 10.1016/s0021-9258(19)85738-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Parish EJ, Schroepfer GJ. Stereoselectivity of raney nickel catalyst in hydrogenolysis of a steroidal α,β-unsaturated epoxide. Chemical synthesis of 3β-benzoyloxy-5α-cholest-8(14)-en-15α-ol. Chem Phys Lipids 1980. [DOI: 10.1016/0009-3084(80)90003-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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10
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Parish EJ, Tsuda M, Schroepfer GJ. Inhibitors of sterol biosynthesis. Syntheses of 14α-alkyl substituted 15-oxygenated sterols. Chem Phys Lipids 1979. [DOI: 10.1016/0009-3084(79)90028-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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11
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Parish EJ, Tsuda M, Schroepfer GJ. Synthesis, properties and reactions of 3 beta-benzoyloxy-7 alpha-15 beta-dichloro-5 alpha-cholest-8(14)-ene. Chem Phys Lipids 1979; 24:167-82. [PMID: 455568 DOI: 10.1016/0009-3084(79)90086-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Treatment of 3 beta-benzoyloxy-14 alpha,15 alpha-epoxy-5 alpha-cholest-7-ene (I) with gaseous HCl in chloroform at -40 degrees C gave, in 87% yield, 3 beta-benzoyloxy-7 alpha,15 beta-dichloro-5 alpha cholest-8(14)-ene (III). Reduction of the latter compound with lithium aluminum hydride in ether at room temperature for 20 min gave, in 86% yield, 7 alpha-15 beta-dichloro-5 alpha-cholest-8(14)-en-3 beta-ol (IV). The latter compound was fully characterized and assignments of the individual carbon peaks in the 13C nuclear magnetic resonance spectra of this sterol have been completed. Reduction of III with excess lithium aluminum hydride in refluxing ether for 4 days gave, in 74% yield, 5 alpha-cholesta-7,14-dien-3 beta-ol (VI). Reduction of the dichloro-steryl benzoate III with lithium triethylborohydride in tetrahydrofuran gave, in 88% yield, 5 alpha-cholest-8(14)-en-3 beta-ol (VII). A similar reduction using lithium triethylborodeuteride led to the formation of [7 beta, 15 xi-2 H2]-VIIa. Treatment of III with concentrated HCl in a mixture of chloroform and methanol gave, in 79% yield, 3 beta-benzoyloxy-5 alpha-cholest-8(14)-en-15-one (II) which was characterized as such and as the corresponding free sterol.
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12
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Spike TE, Martin JA, Huntoon S, Wang AH, Knapp FF, Schroepfer GJ. Sterol synthesis. Chemical synthesis, structure determination and metabolism of 14 alpha-methyl-5 alpha-cholest-7-en-3 beta, 15 beta-diol and 14 alpha-methyl-5 alpha-cholest-7-en-3 beta, 15 alpha-diol. Chem Phys Lipids 1978; 21:31-58. [PMID: 668029 DOI: 10.1016/0009-3084(78)90053-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
14alpha-Methyl-5alpha-cholest-7-en-3beta,15beta-diol and 14alpha-methyl-5alpha-cholest-7-en-3beta,15alpha-diol have been prepared by chemical synthesis. Unequivocal establishment of these structures was based upon X-ray crystallographic analysis of 3beta-p-bromobenzoyloxy-14alpha-methyl-5alpha-cholest-7-en-15beta-ol and was supported by other spectroscopic data. Spectroscopic data were presented for the following compounds prepared in this study: 3beta-benzoyloxy-5alpha-cholest-8(14)-en-15-one, 3beta-benzoyloxy-14alpha-methyl-5alpha-cholest-7-en-15-one, 3beta-benzoyloxy-14alpha-methyl-5alpha-cholest-7-en-15beta-ol, 14alpha-methyl-5alpha-cholest-7-en-3beta, 15beta-diol, 14alpha-methyl-5alpha-cholest-7-en-3beta, 15alpha-cholest-7-en-15beta-diol, 14alpha-methyl-5alpha-cholest-7-en-3beta, 15alpha-diol, 3beta, 15alpha-bis-benzoyloxy-14alpha-methyl-5alpha-cholest-7-ene, 3beta-p-bromobenzoyloxy-14alpha-methyl-5alpha-cholest-7-en-15beta-ol and 3beta, 15beta-bis-p-bromobenzoyloxy-14alpha-methyl-5alpha-cholest-7-ene. Studies of the metabolism of [16-3H]-14alpha-methyl-5alpha-cholest-7-en-3beta, 15beta-diol and [16-3H]-14 alpha-methyl-5 alpha-cholest-7-en-3beta, 15alpha-diol in liver homogenates of female rats indicated that only the 3beta, 15beta-diol was convertible to cholesterol.
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Huntoon S, Fourcans B, Lutsky B, Parish E, Emery H, Knapp F, Schroepfer G. Sterol Synthesis. Chemical syntheses, spectral properties, and metabolism of 5alpha-cholest-8(14)-en-3beta,15beta-diol and 5alpha-cholest-8(14)-en-3beta,15alpha-diol. J Biol Chem 1978. [DOI: 10.1016/s0021-9258(17)38170-x] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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15
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Parish EJ, Schroepfer GJ. Sterol synthesis. Syntheses of 15-oxygenated 5alpha, 14beta-cholest-7-en-3beta-ol derivatives. Chem Phys Lipids 1977; 19:107-13. [PMID: 880727 DOI: 10.1016/0009-3084(77)90091-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Treatment of 3beta-benzoyloxy-14alpha, 15alpha-epoxy-5alpha-cholest-7-ene with boron trifluoride-etherate gave, in 43% yield, 3alpha-benzoyloxy-5alpha, 14beta-cholest-7-en-15-one with the unnatural C-D ring juncture. Reduction of the latter compound with lithium aluminum hydride gave 15alpha, 14beta-cholest-7-en-3beta, 15alpha-diol and 5alpha, 14beta-cholest-7-en-3beta, 15beta-diol in 9% and 81% yields, respectively.
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Parish EJ, Schroepfer GJ. Sterol synthesis. A novel reductive rearrangement of an alpha,beta-unsaturated steroidal epoxide; a new chemical synthesis of 5alpha-cholest-8(14)-en-3beta, 15alpha-diol. Chem Phys Lipids 1977; 18:258-66. [PMID: 858170 DOI: 10.1016/0009-3084(77)90013-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Reduction of 3beta-benzoyloxy-14alpha,15alpha-epoxy-5alpha-cholest-7-ene with either lithium triethylboro-hydride or lithium aluminum hydride (4 molar excess) gave 5-alpha-cholest-8(14)-en-3beta,15alpha-diol in high yield. Reduction of the epoxy ester with lithium triethylborodeuteride or lithium aluminum deuteride (4 molar excess) gave [7alpha-2-H]-5alpha-cholest-8(14)-en-3beta,15alpha-diol. Reduction of 2beta-benzoyloxy-14alpha,15alpha-epoxy-5alpha-cholest-7-ene with a large excess (24 molar excess) of lithium aluminum hydride gave, in addition to the expected 5alpha-cholest-8(14)-en-3beta,15alpha-diol, a significant yield (33%) of 5alpha-cholest-8(14)-en-3beta-o1. Reduction of the epoxy ester with a large excess (24 molar excess) of lithium aluminum deuteride gave [7alpha-2H]-5alpha-cholest-8(14)-en-3beta,15alpha-diol and 5alpha-cholest-8(14)-en-3beta-o1 which contained two atoms of stably bound deuterium.
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Parish EJ, Spike TE, Schroepfer GJ. Sterol synthesis. Chemical synthesis of 3beta-benzoyloxy -14alpha, 15alpha-epoxy-5alpha-cholest-7-ene, a key intermediate in the synthesis of 15-oxygenated sterols. Chem Phys Lipids 1977; 18:233-9. [PMID: 870213 DOI: 10.1016/0009-3084(77)90011-1] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
3BETA-Benzoyloxy-14alpha, 15alpha-cholest-7-ene was obtained in 96% yield upon treatment of 3beta-benzoyloxy-5alpha-cholesta-7, 14-diene with m-chloroperbenzoic acid. The delta7-14alpha, 15alpha-epoxy-steryl ester provides a useful intermediate for the syntheses of sterols with an oxygen function at carbon atom 15. For example, treatment of 3beta-benzoyloxy-14alpha, 15alpha-epoxy-5alpha-cholest-7-ene with methanolic hydrochloric acid gave 3beta-benzoyloxy-5alpha-cholest-8(14)-en-15-one in 82% yield.
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Conner BN, Parish EJ, Schroepfer GJ, Quiocho FA. Synthesis an crystal structure of 3beta-p-bromobenzoyloxy-14alpha, 15alpha-epoxy-5alpha-cholest-7-ene. Chem Phys Lipids 1977; 18:240-7. [PMID: 870214 DOI: 10.1016/0009-3084(77)90012-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The chemical synthesis of 3beta-bromobenzoyloxy-14alpha, 15alpha-epoxy-5alpha-cholest-7-ene is described. Single crystal structral analysis was employed to unambiguously determine the location and absolute configuration of the epoxide moiety in the 3beta-p-bromobenzoyloxy-14alpha, 15alpha-epoxy-5alpha-cholest-7-ene. The space group of the crystal was P1, with unit cell parameters: a=10.873 A, b=13.841 A, c=11.037 A, alpha=75.19 degrees, beta=78.79 degrees, gamma=101.57 degrees, and two molecules per unit cell. Intitial phases were derived from the two bromine atoms. Least squares refinements on all non-hydrogen atoms were carried out to a final unweighted R value of 0.10 and weighted R value of 0.04. The epoxide ring was located at the 14, 15 position and was found to extend to the alpha side of the molecule. Molecular measurements for asymmetry parameters of the sterol nuceus indicate that ring A has a symmetrical chair conformation and ring B has a half chair conformation due to the double bond at C(7). Ring C has a fairly distorted chair conformation due to the trigonal C(8) on one sie and the almost planar 5-membered ring on the other. Ring D has the 17alpha-envelope conformation.
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Parish E, Schroepfer C. A novel reductive rearrangement of an α,β-unsaturated steroidal epoxide. A new synthesis of 5α-cholest-8(14)-en-3β,15α-diol. Tetrahedron Lett 1976. [DOI: 10.1016/s0040-4039(00)93107-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Raulston DL, Mishaw CO, Parish EJ, Schroepfer GJ. Inhibition of hepatic sterol synthesis and reduction of serum cholesterol in rats by 5alpha-cholest-8(14)-en-3beta-ol-15-one. Biochem Biophys Res Commun 1976; 71:98409. [PMID: 971324 DOI: 10.1016/0006-291x(76)90751-8] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Gibbons GF, Mitropoulos KA, Pullinger CR. Lanosterol 14alpha-demethylase. The metabolism of some potential intermediates by cell-free systems from rat liver. Biochem Biophys Res Commun 1976; 69:781-9. [PMID: 1267815 DOI: 10.1016/0006-291x(76)90943-8] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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Phillips GN, Quiocho FA, Sass RL, Werness P, Emery H, Knapp FF, Schroepfer G. Sterol biosynthesis: Establishment of the structure of 3β-p-bromobenzoyloxy-5α-cholest-8(14)-en-15β-ol. Bioorg Chem 1976. [DOI: 10.1016/0045-2068(76)90011-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Gibbons GF, Mitropoulos KA. Effect of trans-1,4-bis(2-chlorobenzylaminomethyl) cyclohexane dihydrochloride and carbon monoxide on hepatic cholesterol biosynthesis from 4,4,-dimethyl sterols in vitro. BIOCHIMICA ET BIOPHYSICA ACTA 1975; 380:270-81. [PMID: 1120146 DOI: 10.1016/0005-2760(75)90013-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The drug trans-1,4-bis(2-chlorobenzylaminomethyl)cyclohexane dihydrochloride (AY-9944) almost completely inhibited the conversion of [2-14C] mevalonic acid, dihydro[14C]lanosterol, 4,4-dimethyl-5alpha-[2-3H2]cholesta-8,14-dien-3beta-ol and 4,4-dimethyl-5alpha-[2-3H2]cholest-8(14)-en-3beta-ol to 5alpha-cholest-7-en-3beta-ol and cholesterol by cell-free systems of rat liver. With the first three precursors, the inhibition was accompanied by an accumulation of radioactive 5alpha-cholesta-8,14-dien-3beta-ol, but this material could not be detected during inhibition of cholesterol biosynthesis from 4,4-dimethyl-5alpha-[2-3H2] cholest-8(14)-en-3beta-ol. Regardless of the nature of the precursor, trans-1,4-bis(2-chlorobenzylaminomethyl)cyclohexane dihydrochloride did not result in the accumulation of any delta5,7 sterols. Non-radioactive 5alpha-cholest-8(14)-en-3beta-ol inhibited the conversion of dihydro[14C]lanosterol to 4,4-dimethyl-5alpha-cholesta-8,14-dien-3beta-ol. Carbon monoxide resulted in a decrease in the rate of conversion of dihydro[14C]lanosterol to 4,4-dimethyl-5alpha-cholesta-8,14-dien-3beta-ol but had no effect on the rate of conversion of 4,4-dimethyl-5alpha-[2-3H2]cholesta-8,14-dien-3beta-ol to 5alpha-cholest-7-en-3beta-ol and cholesterol suggesting that cytochrome P-450 is involved neither in the oxidative removal of the 4-methyl groups nor in the oxidative introduction of the delta5 bond during cholesterol biosynthesis. In addition, the process of cholesterol and 5alpha-cholest-7-en-3beta-ol biosynthesis from 4,4-dimethyl-5alpha-[2-3H2]cholest-8(14)-en-3beta-ol was inhibited by carbon monoxide at a stage after the formation of 5alpha-cholest-8(14)-en-3beta-ol.
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Gibbons GF. The metabolic sequence by which some 4,4-dimethyl sterols are converted into cholesterol. Biochem J 1974; 144:59-68. [PMID: 4462576 PMCID: PMC1168464 DOI: 10.1042/bj1440059] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Cholest-8(14)-enol is the major radioactive component of the 4-di-demethyl sterol fraction biosynthesized from 4,4-dimethyl[2-(3)H(2)]cholest-8(14)-enol by rat liver microsomal fractions, and therefore the first steps in the biosynthesis of cholesterol from the latter compound probably involve removal of the 4-methyl groups. 4,4-Dimethylcholesta-8,14-dienol therefore is not an intermediate in this process, although its presence in the incubation medium at a concentration of 0.146mm almost completely inhibits the demethylation of 4,4-dimethyl[2-(3)H(2)]cholest-8(14)-enol. Nor is cholesta-8,14-dienol an intermediate in the conversion of cholest-8(14)-enol into cholest-7-enol and cholesterol. With 4,4-dimethyl[2-(3)H(2)]cholesta-8,14-dienol as the cholesterol precursor, 4,4-dimethylcholest-8(9)-enol becomes heavily labelled and there is very little radioactivity associated with cholesta-8,14-dienol. In this case, the most heavily labelled 4-di-demethyl sterols are cholest-7-enol and cholesterol with the former predominating. There is little or no radio-activity associated with cholest-8(14)-enol. A similar labelling pattern amongst the 4-di-demethyl sterols was observed with dihydro[(14)C]lanosterol as the precursor. The first step therefore in the synthesis of cholesterol from the 4,4-dimethyl[2-(3)H(2)]dienol is reduction of the Delta(14(15)) bond and not removal of the 4alpha-methyl group. Depending on the nature of the precursor, addition of the soluble fraction of the cell to the microsomal fraction resulted in a two- to four-fold stimulation of 4-di-demethyl sterol biosynthesis from the 4,4-dimethyl sterols studied. Under these conditions, 4,4-dimethylcholesta-8,14-dienol is the most efficient precursor of cholesterol and cholest-7-enol, and dihydrolanosterol is better than 4,4-dimethylcholest-8(14)-enol.
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Gibbons GF, Mitropoulos KA. The rôle of cytochrome P-450 in cholesterol biosynthesis. EUROPEAN JOURNAL OF BIOCHEMISTRY 1973; 40:267-73. [PMID: 4149283 DOI: 10.1111/j.1432-1033.1973.tb03194.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Lutsky BN, Schroepfer GJ. Enzymatic conversion of 5alpha-cholest-8(14)-en-3beta-o1 to 5alpha-cholesta-8,14-dien-3beta-o1. Lipids 1971; 6:957-9. [PMID: 5163761 DOI: 10.1007/bf02531180] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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Lutsky BN, Martin J, Schroepfer G. Studies of the Metabolism of 5α-Cholesta-8,14-dien-3β-ol and 5α-Cholesta-7,14-dien-3β-ol in Rat Liver Homogenate Preparations. J Biol Chem 1971. [DOI: 10.1016/s0021-9258(19)45907-3] [Citation(s) in RCA: 45] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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