Polyterpene und Polyterpenoide XCI. Zur präparativen Herstellung des Koprosterins, epi‐Koprosterins und epi‐Dihydro‐cholesterins. Beitrag zur Kenntnis der räumlichen Lage der Hydroxylgruppe bei den Sterinen

Ruzièka, L.; Brüngger, H.; Eichenberger, E.; Meyer, Jules

doi:10.1002/hlca.193401701171

Cited by 65 publications

(4 citation statements)

References 6 publications

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“…The ether phase was evaporated and 58-cholestan-3-one was crystallized from a methanol-water mixture. The yield was 3 mg, m. p. 61-63", reported m. p. 61-62" [32]. This matcrial was refluxcd in a solution of potassium hydroxide in methanol (10 Ole, wlv) for 20 hours.…”

Section: Materials [4-14c]cholest-5-ene-3brcr-diol (I)mentioning

confidence: 99%

On the Mechanism of the Enzymatic Conversion of Cholest-5-ene-3beta,7alpha-diol into 7alpha-Hydroxycholest-4-en-3-one

Björkhem

1969

Eur J Biochem

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The conversion of cholest-5-ene-3p,7a-diol into 7a-hydroxycholest-4-en-3-one in the presence of rat liver microsomes fortified with NAD was studied with the aid of [4-14C]-, [3a-3H]-, [4p-3H]-, and [4@-2H]cholest-5-ene-3B,7a-diol. The reaction was also carried out in 3H,0 and ,H,O and the incorporation of isotope in the product was determined. It was found that the rate-limiting step in the reaction involved loss of the 3a-hydrogen. This step was coupled with or followed by loss of hydrogen from the 4p-position, of which a small amount was transferred to the 6/?-position of the product.The major pathways for the conversion of cholesterol into chenodeoxycholic acid and cholic acid in rat liver involve cholest-5-ene-3~,7a-diol and 7a-hydroxycholest-4-en-3-one as intermediates [I]. The transformation of cholest-5-ene-3/?,7a-diol into 7a-hydroxycholest-4-en-3-one is catalyzed by the microsoma1 fraction and NAD is the preferred cofactor [2,3]. The detailed enzymatic and stereochemical features of the reaction are not known. I n a study of the transformation of [4/?-SH]cholesterol into bile acids in the bile fistula rat, Green and Samuelsson found that the main part of the 4b-hydrogen was lost and a small part was transferred to the 6@-position [4]. I n view of present knowledge of the pathways of bile acid biosynthesis it is probable that these events occur mainly during the transformation of cholest-5-ene-3@,7a-diol into 7a-hydroxycholest-4-en-3-one. However, it appeared possible that more detailed information concerning this reaction might be provided by studies in vitro. The present communication describes a series of experiments on the formation of 7a-hydroxycholest-4-en-3-one from cholest-5-ene-3B,7a-diol labeled with 3H and 2H in specific positions.

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Section: Materials [4-14c]cholest-5-ene-3brcr-diol (I)mentioning

confidence: 99%

On the Mechanism of the Enzymatic Conversion of Cholest-5-ene-3beta,7alpha-diol into 7alpha-Hydroxycholest-4-en-3-one

Björkhem

1969

Eur J Biochem

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“…To parallel the above work, the mixture of sterols was oxidized in such a manner as to give both P-sitostenone and p-sitostanone. This was achieved by bromi~lating the mixture, oxidizing the p-sitosterol dibromide and p-sitostanol in a two-phase system with chromium trioxide (9), removing the bromine from the dibromide by means of sodium iodide ( l l ) , and chromatographi~lg the resulting mixture. Both P-sitostenone and p-sitostanone were obtained, although the former was not quite as pure as desirable.…”

Section: Introductionmentioning

confidence: 99%

The Chemistry of Peat Part: I. The Sterols of Peat Moss (Sphagnum)

Ives¹,

O'Neill²

1958

Can. J. Chem.

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Peat moss (Sphagnunt) from the surface of a n Atlantic peat bog has been extracted with a mixture of benzene and ethanol. The extract has been fractionated chromatographically 011 alumina. A mixture of sterols has been isolated from one fraction. 'This mixture has been proved by oxidation experiments to consist of 8-sitosta~lol (stigmastanol) and 8-sitosterol. I t constit~~ted approximately 0.2y0 by weight of the dried peat ~noss. INTRODUCTIONA considerable amount of work has been done on the chemical composition of peat (8), lignite (brown coal) (8)) and coal (8), but relatively little on the conlposition of peal: moss (Sphagnum). The latter is considered to be the main precursor of peat in the Atlantic area of Canada. This work was undertalien ill a n effort to remedy this defect, and also to ascertain what chemical changes occur in huinification. Black and his coworkers (4) carried out an extensive analysis on a sample of peat moss from Scotland and reported the presence of p-sitosterol.The peat moss used in our experiments was a living surface moss, from Shipigan, New Brunswick, ancl was essentially a mixture of Splzngnunz fuscum, S . capillacer~m, and S . magellanicum with the first two predominating. It was comparatively free of other common bog plants. T h e moss was clried to a moisture content of approximately 5% and ground to pass through a 20-mesh screen. Only relatively small quantities of the powder could be extracted a t a time, ouring to its bull;. The process used was a continuous extractioi~ method, with a constant stream of pure solvent passing through the moss.After evaporation of the solvent, the clarl; brourn guin (approximatell. 6% of the total solids) was saponified with methanolic potassiun~ hydroxide solution ancl the unsaponiliable material extractecl with ether. This extract (approximately 1.5% of the total solids), after evaporation, was dissolved in light petroleum and chromatographed roughly on alumina. A small portion of the gun1 (approximately 3%) did not dissolve in the petrol and was kept for further investigation. The eluate from the chromatogram was divided into five fractions: materials eluted progressively by ( a ) light petroleum, (b) benzene, (c) ether, (d) ether containing 10% ~nethanol, and (e) ~nethanol. These iractioils will be described separately. T h e coinposition of fractions (c) and (d) varied from extraction to extraction and with the grade of alumina used. The ether fraction so~netimes consisted of a white, low-melting solid, and the ether-methanol fraction of a colorless crystalline solicl, subsequently proved t o be the sterols. In the majority of extractions, however, the con~ponents were c nixed and tended to be removed fro~n the column together in fraction (d) as a light yellow glass. T h e ~nixture was separated into cyclic and linear aliphatic compounds by treatment with urea with which the latter formed an insoluble complex. Decompositio~l of the complex yielded an alcohol which has been tentativel!. identified as lignoceryl alcohol by meltin...

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“…The stereochemistry of the alcohols resulting from the catalytic hydrogenation of steroidal ketones has been known to be very sensitive to the reaction medium (1)(2)(3), and the reason for this is a debated point (3,4). On the other hand, the substituent effect on the stereochemistry of hydrogenation of ketones has not yet been well examined, and an investigation of the effect of some substituents in a rather rigid steroidal system seems to be of interest.…”

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confidence: 99%

“…The proportion of the 3a-alcohol obtained in hydrogenation of 5a-cholestan-3-one over platinum has been reported to vary with acidity of the solvent used (1,2), and the 3a-alcohol became the main product of hydrogenation by adding small amounts of hydrochloric acid to the solvent (3). As the stereochemistry of the hydrogenation of steroidal 3-ketones appears very susceptible to the influence of the condition of the reaction, for instance, the catalyst used, solvent, temperature and other factors, the proportion of 3a-alcohols obtained in hydrogenation of several ketones under the same condition was compared with that of 5a-cholestan-3-one in the present experiments.…”

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confidence: 99%