Showing papers on "Lanosterol published in 1970"
TL;DR: It is concluded from measurements of the 3H:14C ratios found in these various compounds that the 4α-methyl group of lanosterol is removed before the 4β- methyl group and that the 2,4,14α-trimethyl-5α-cholesta-8,24-dien-3β-ol originates as the 4 β-methyl Group of Lanosterol.
29 citations
27 citations
TL;DR: After removal of cholesterol on a digitonin column, the unsaponifiable matter of milk fat was examined for alcoholic substituents and dihydrolanosterol and lanosterol, previously identified but never confirmed, were characterized.
26 citations
TL;DR: In this article, the sterols 24,25-dihydro-4α-methyl-24-methylene-lanosterol and 3β-hydroxy 4β-methylcholesta-8(14),24-diene have been isolated from yeast residues and their structures have been determined.
Abstract: 24,25-Dihydro-24-methylenelanosterol has been synthesised from lanosterol and investigated as a potential precursor of eburicoic acid and of ergosterol.Two new sterols, 24,25-dihydro-4α-methyl-24-methylenezymosterol and 3β-hydroxy-4α-methylcholesta-8(14),24-diene have been isolated from yeast residues and their structures have been determined. The constitution of 24,25-dihydro-4α-methyl-24-methylenezymosterol has been confirmed by a partial synthesis from the more abundant 4α-methylzymosterol.4α-Methylzymosterol, 24,25-dihydro-4α-methyl-24-methylenezymosterol and obtusifoliol have been shown to be incorporated into ergosterol in yeast cultures. 4,4-Dimethylergosterol is, however, not a precursor.By a trapping experiment in which tritium-labelled squalene oxide and unlabelled 24,25-dihydro-24-methylene-lanosterol were used it has been shown that the latter is almost certainly not on the biogenetically preferred route from lanosterol to ergosterol.
23 citations
TL;DR: The results suggest that the C-7 hydrogen atoms with opposite stereochemistry are labilized by the rat liver and the yeast Delta(8)-Delta(7) steroid isomerases.
Abstract: The synthesis of [7α-3H]lanosterol is described. It is shown that in the conversion of [7α-3H,26,27-14C2]lanosterol into cholesterol by a rat liver system, it is the 7β-hydrogen atom that is predominantly removed. On the other hand, the conversion of doubly labelled lanosterol into ergosterol by whole yeast cells results in the loss of the 7α-hydrogen atom. These results therefore suggest that the C-7 hydrogen atoms with opposite stereochemistry are labilized by the rat liver and the yeast Δ8–Δ7 steroid isomerases.
22 citations
TL;DR: The results suggest that, in addition to control of cholesterol biosynthesis at the stage of mevalonic acid formation, the rate of cholesterolgenesis may be controlled by activities of enzymes associated with the reactions that occur after lanosterol formation.
21 citations
19 citations
TL;DR: 3β-Acetoxylanosta-8,24-diene (1) has been converted by a six-step degradation into 3β-acetoxy-4,4,14α-tri-methyl-5α-pregn-8-en-2-one (14).
15 citations
13 citations
TL;DR: By stepwise oxidative degradation of the side chain of lanosterol (1a), 3β-hydroxy-4,4,14-trimethyl-Δ8-5α-pregnen-20-one (15a) has been obtained (overall yield 10%).
13 citations
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TL;DR: The results of thin layer and gas chromatographic analyses indicate that a large quantity of cholesterol and considerable amounts of lanosterol, desmosterol, δ7-cholestenol, cholestanol, and 4a-methyl-δ8,24- cholESTenol were found to be present in egg yolk.
Abstract: SUMMARY
This investigation was initiated to separate the unsaponifiable matter of egg yolk by thin layer chromatography (TLC) and attempt to identify the steroids by gas liquid chromatography (GLC). Three GLC liquid phases, differing in selective partition properties, were used to aid in the identification of unknown steroids. A selective method was also carried out to extract the estrogenic steroids in egg yolk if present. The results of thin layer and gas chromatographic analyses indicate that a large quantity of cholesterol and considerable amounts of lanosterol, desmosterol, δ7-cholestenol, cholestanol, δ7- and δ8-methostenol, 4a-methyl-δ8,24-cholestenol and its δ7-isomer, 4,4a-dimethyl-δ7,24-cholestenol, dihydrolanostenol, β-sitosterol and possibly ergosterol were found to be present in egg yolk. Estrogenic steroids and other known steroid hormones were not found in egg yolk.
TL;DR: In this article, evidence is presented that is consistent with cucurbitacin B being biosynthesized via cycloartenol or parkeol but not through the intermediacy of lanosterol.
Abstract: Evidence is presented that is consistent with cucurbitacin B being biosynthesized via cycloartenol or parkeol but not through the intermediacy of lanosterol.
TL;DR: In this article, the second-order Beckmann cleavage of 3-hydroxyimino-5α-lanostane was used as an intermediate in the conversion of lanosterol into 14α-methylcholest-4-en-3-one.
Abstract: 3,4-Seco-5α-lanost-4(30)-en-3-onitrile, obtained by ‘second-order’ Beckmann cleavage of 3-hydroxyimino-5α-lanostane, has been used as an intermediate in the conversion of lanosterol into 14α-methylcholest-4-en-3-one.
TL;DR: In this paper, the 7β-hydrogen of lanosterol derived from the 2proS hydrogen of mevalonic acid (MVA) was removed in the biosynthesis of α-spinasterol.
Abstract: It is indicated that the 7β-hydrogen of lanosterol derived from the 2-proS hydrogen of mevalonic acid (MVA) is removed in the biosynthesis of α-spinasterol.
TL;DR: Sterol composition in human brain and brain tumors was determined using combined chromatographic techniques and the loss of the 15α hydrogen of lanosterol is described and the presence of a new series of cholesterol precursors (sterols containing a 8,14 diene system) is demonstrated.
TL;DR: In this paper, it has been shown that the demethylation of lanosterol involves hydroxylation of the methyl group and this process must differ from certain P450-dependent mixed function oxidases which are stimulated by similar concentrations of β-mercaptoethylamine.
Journal Article•
Patent•
16 Mar 1970
TL;DR: In this paper, the authors presented a novel method of pre-preparing steroids in the presence of the 3-OXO-4-ENE groupings, from TETRACYCLIC TRITERPENes SUCH as LANOSTEROL.
Abstract: THERE IS PROVIDED A NOVEL METHOD OF PREPARING STEROIDS HAVING THE CYCLOPENTANOPHENANTHRENE NUCLEUS, IN PARTICULAR THOSE POSSESSING THE VALUABLE 3-OXO-4-ENE GROUPINGS, FROM TETRACYCLIC TRITERPENES SUCH AS LANOSTEROL THE METHOD COMPRISES CONVERTING LANOSTEROL TO THE CORRESPONDING 3B-HYDROXY-5A-LANOSTANE WHICH IS THEN SUBJECTED TO A-RING CONTRACTION TO GIVE THE KNOWN 3-OXO-ANOR-14A-METHYL CHOLESTANE THE FIVE MEMBERED "A" RING IS CONVERTED TO THE CORRESPONDING 3-OXO-4-OXA COMPOUND THIS LACTONE IS OXIDIZED TO THE CORRESPONDING 3,5-SECO-5OXO-3-OIC ACID, DEHYDRATION LEADS TO RING CLOSURE AND FORMATION OF THE $5 LACTONE THIS $5 LACTONE IS CLEAVED BY, FOR EXAMPLE, THE ACTION OF A GRIGNARD AGENT TO YIELD THE CORRESPONDING TRICYCLIC 3,5-DIONE WHICH IS RING CLOSED BY THE ACTION OF A STRONG BASE TO GIVE THE CORRESPONDING VALUABLE 3-OXO-4-ENE STEROID THE METHOD HAS GREAT AND SURPRISING FLEXIBILITY IN BEING SUBSTANTIALLY UNAFFECTED BY SUBSTITUTION PATTERNS IN THE B, C OR D RINGS OF THE NUCLEUS THE METHOD THUS PRESENTS LANOSTEROL AS A CHEAP AND READILY AVAILABLE RAW MATERIAL FOR MOST KNOWN STEROIDS AND IS THUS A DESIRABLE ALTERNATIVE TO THE PRESENTLY USED DIOSGENIN FOR THIS PURPOSE
TL;DR: Nach intramuskulärer Injektion von 50 mg/kp Di methoat am Schaf konnten wir im Blut Wirkstoffkon zentrationen von 3 — 4 mg/Z bis zu 8 h p.
Abstract: binationen und unter Erhöhung der Dosis auf 50 mg/kp werden im Blut kurzzeitig Wirkstoffkonzentrationen von etwa 1 mg/Z erreicht (s. Abb. 1). Auch bei der Pour on-Applikation von Fenthion und Bayer 9017 am Schaf wurden bereits ähnliche ausgeprägte Abhängig keiten der percutanen Resorption vom Lösungsmittel beobachtet 6. Wie aus Abb. 1 weiterhin beim Vergleich der Ergeb nisse für Rind und Schaf hervorgeht, wird Dimethoat beim Schaf schwieriger resorbiert als beim Rind im Vergleich zum Trichlorphon. Nach intramuskulärer Injektion von 50 mg/kp Di methoat am Schaf konnten wir im Blut Wirkstoffkon zentrationen von 3 — 4 mg/Z bis zu 8 h p. i. nachweisen; auch daran erkennt man die erschwerte percutane Re sorption am Schaf.