Showing papers on "Lanosterol published in 1972"
TL;DR: A specific and sensitive means of detection of sterol hydroperoxides on irrigated thin-layer chromatoplates using N,N-dimethyl-p-phenylenediamine dihydrochloride has been developed and autoxidation of cholesterol in the solid state, in the irradiated solidState, in colloidal dispersion, and in aerated solution is shown.
128 citations
TL;DR: All the detectable sterols of yeast (Saccharomyces cerevisiae) with polarities (as measured by their RF values on silica gel)⩽ ergosta-5,7,22,24(28)-teraen-3β-ol have been isolated and characterised and lanosterol has been shown to be a mixture.
Abstract: All the detectable sterols of yeast (Saccharomyces cerevisiae) with polarities (as measured by their RF values on silica gel)⩽ ergosta-5,7,22,24(28)-teraen-3β-ol have been isolated and characterised. In addition to the known fully defined sterols, lanosterol. 14-demethyl-lanosterol, 4α-methylzymosterol, 24,25-dihydro-4α-methyl-24-methylenezymosterol, zymosterol,5,6-dihydroergosterol, ergosta-5,7,22,24(28)-tetraen-3β-ol, and ergosterol, the less well characterised sterols, fecosterol and episterol, have been reisolated and the structures confirmed. Sterols previously unreported in yeast, parkeol, ergost-7-en-3β-ol, ergosta-7,22,24(28)-trien-3β-ol, and ergosta-5,7,24(28)-trien-3β-ol have also been isolated and characterised. Ascosterol has been shown to be a mixture.
43 citations
TL;DR: In this article, a study was made of the methyl sterols involved in sterol biosynthesis in developing rat brain and the determination of the endogenous sterols present in 15-day-old rat brain was conducted to establish which of these sterols could be labeled by a minced tissue preparation in the presence of [2-14C]mevalonic acid.
23 citations
TL;DR: It is shown that significantly more endogenously generated NADPH is available for reduction of corticosterone in liver homogenates from C57BL/10 male mice than in those from the DBA/2 strain, which mainly produces lanosterol and other precursors of cholesterol which require NADPH for their further metabolism.
22 citations
TL;DR: Some mechanisms in the formation of cholesterol and its sterol precursors from lanosterol are discussed and the relation between in vitro and in vivo pathways of cholesterol biosynthesis and the composition and metabolism of sterols in biological tissues is underlined.
Abstract: The conversion of lanosterol║to cholesterol requires a considerable number of intermediary steps involving loss or uptake of hydrogen atoms and formation and migration of nuclear double bonds. Detailed discussions on the intermediary steps in cholesterol biosynthesis are reported in several reviews (Olson 1965; Frantz & Schroepfer 1967; Goad 1970). In the present report some mechanisms in the formation of cholesterol and its sterol precursors from lanosterol are discussed. The relation between in vitro and in vivo pathways of cholesterol biosynthesis and the composition and metabolism of sterols in biological tissues is underlined.
22 citations
TL;DR: A convenient method for the separation of the two isomers of 24ξ,25-epoxy-5α-lanost-8-en-3β-yl acetate is described and a number of related compounds have been prepared and their absolute configurations determined by correlation with the above compounds.
Abstract: A convenient method for the separation of the two isomers of 24ξ,25-epoxy-5α-lanost-8-en-3β-yl acetate is described. The absolute configuration of these compounds is established by their conversion into the corresponding 5α-lanost-8-ene-3β,24ξ-diol 3-acetates, and thence by Horeau's method (treatment with α-phenylbutyric anhydride), and by the method of molecular rotation differences. A number of related compounds have also been prepared and their absolute configurations determined by correlation with the above compounds.
14 citations
TL;DR: In all experiments most of the radioactivity of the liver was transformed to cholesterol and the conversion of squalene to cholesterol proceeded more slowly in the kidneys and 30 min after the administration of the mevalonate substantial amounts of radioactivity was recovered as labelledsqualene and lanosterol.
Abstract: DL-mevalonate-2-14C was administered parenterally to 2 rabbits and 5 groups of mice. In the rabbits the amount of labelled material recovered in the non-saponifiable lipids of the kidneys exceeded that of the liver. Most of the renal radioactivity was found in the squalene, lanosterol and methostenol fractions whereas the major part of the labelled material in the liver was present as radioactive cholesterol. The distribution of radioactivity within the kidney and the liver in the mice varied with the size of the administered dose. The smaller the dose, the larger the proportion of label recovered in the kidneys. In all experiments most of the radioactivity of the liver was transformed to cholesterol. The conversion of squalene to cholesterol proceeded more slowly in the kidneys and 30 min after the administration of the mevalonate substantial amounts of radioactivity was recovered as labelled squalene and lanosterol. The importance of circulating mevalonate as substrate in the cholesterol synthesis of the kidney will be discussed.
14 citations
13 citations
TL;DR: Attempts to prepare 3β-acetoxylanost-7-en-32-oic acid are reported, together with some novel methods for the oxidation of sterically hindered aldehydes as exemplified by using pivalaldehyde as a model compound.
Abstract: Lanosterol has been converted into 3β-acetoxylanost-7-en-32-onitrile and thence into 3β-acetoxylanost-7-en-32-al and 3β,32-diacetoxylanost-7-ene. 3β-Acetoxy-11-oxolanost-8-en-32-onitrile and methyl 3β-acetoxy-32-nitrilo-11-oxo-25,26,27-trinorlanost-8-en-24-oate have been synthesised by an analogous route. Unsuccessful attempts to prepare 3β-acetoxylanost-7-en-32-oic acid are reported, together with some novel methods for the oxidation of sterically hindered aldehydes as exemplified by using pivalaldehyde as a model compound.
12 citations
TL;DR: It is shown unequivocally that the compounds thus obtained have the unnatural 14β-configuration.
Abstract: Methods are described for the removal of carbon atom 32 from certain 32-functionalised lanosterol derivatives. It is shown unequivocally that the compounds thus obtained have the unnatural 14β-configuration.
9 citations
TL;DR: In intact sham-operated rats given the control diet the labeled non-saponifiable lipids of the kidneys exceeded the amounts of such material recovered in other tissues analyzed, and the role of the kidney in the metabolism of circulating mevalonate was studied.
Abstract: The aim of the investigation was to study the role of the kidney in the metabolism of circulating mevalonate DL-mevalonate-2- 14 C was injected intravenously to sham-operated and nephrectomized rats that were sacrificed after 90 min The diet given to part of the animals prior to the experiments were supplemented with 5% cholesterol In intact sham-operated rats given the control diet the labeled non-saponifiable lipids of the kidneys exceeded the amounts of such material recovered in other tissues analyzed The kidneys also differed from many other organs with regard to the slow rate by which squalene and lanosterol were converted to C27 sterols Following nephrectomy there was a marked increase of the labeled nonsaponifiable lipids of the liver and blood As in the intact rats the major part of this label was recovered in the C27 sterol fraction The radioactivity in the C27 sterol fraction of the liver decreased upon cholesterol feeding This change was balanced by a reciprocal elevation of labeled squalene and lanosterol whereby the total amounts of the labeled nonsaponifiable lipids was uninfluenced by the supplementation of cholesterol to the diet
TL;DR: It is tentatively concluded that endosperm tissue, which is not functionally photosynthetic, biosynthesizes sterols through cycloartenol rather than lanosterol, which suggests in turn that the entirety of a Photosynthetic organism, rather than just photosynthetics tissue, operates the steroid pathway through the cyclOartenol route.
TL;DR: Gas—liquid chromatography and gas chromatography—mass spectrometry have been used to study the pattern of sterols in meconium and faeces from newborn infants.
Abstract: Gas—liquid chromatography and gas chromatography—mass spectrometry have been used to study the pattern of sterols in meconium and faeces from newborn infants. Meconium contained metabolites from various steps in the biosynthesis of cholesterol, e. g. lanosterol, 24, 25-dihydro-∆ 8 -lanosterol, 24, 25-dihydro-∆ 9 -lanosterol, 4 α ,14 α -dimethyl-5 α -cholest-7 (and 8)-en-3 β -ol, 4, 4-dimethyl-5 α -cholest-8-en-3 β -ol, 4, 4-dimethyl-5 α -cholesta-8, 14-dien-3 β -ol and ∆ 7 - and ∆ 8 -methostenol. Meconium and faeces from newborns also contained the sulphate esters of 20, 22-dihydroxycholesterol and of 22-, 23- and 24-hydroxycholesterol.
TL;DR: In order to obtain antitumor substances the diosphenols 6a, b, 8, 10 and 11a, c have been prepared by the method of Barton after oxidative degradation of lanosterol.
TL;DR: A boron trifluoride-catalysed ‘backbone’ rearrangement of this epoxide produced 3β-acetoxy-29-nor-8α, 14β-dammara-9(11), 13(17)-diene and 3 β- acetoxy-4 α, 14α-dimethyl-5α, 9β-cholestan-11-one.
Abstract: A recently established method for the monodemethylation of triterpenes at C-4 has been used to convert lanosterol into 3β-acetoxy-9,11α-epoxy-4α, 14α-dimethyl-5α-cholestane. A boron trifluoride-catalysed ‘backbone’ rearrangement of this epoxide produced 3β-acetoxy-29-nor-8α, 14β-dammara-9(11), 13(17)-diene and 3β-acetoxy-4α, 14α-dimethyl-5α, 9β-cholestan-11-one.
TL;DR: The purpose of this short account is to present some results which cast doubt on the validity of the methods used generally for the study of phytosterol biosynthesis (though not necessarily on the legitimacy of the conclusions arrived at).
Abstract: The purpose of this short account is to present some results which cast doubt on the validity of the methods used generally for the study of phytosterol biosynthesis (though not necessarily on the validity of the conclusions arrived at). We shall accept, and not discuss, the present general framework of interpretation of sterol biosynthesis (chart 1) (see for example Goad 1970). Key intermediates, from our point of view, are squalene, squalene epoxide, and a triterpene alcohol: lanosterol in vertebrates and in fungi, cycloartenol in the green plants. The transformation squalene-squalene epoxide is an oxidative step; the transformation squalene epoxidetriterpene alcohol is the biochemical equivalent of an acidcatalysed isomerization.
TL;DR: These experiments indicate that the sheep and pig feto-placental endocrine systems have the potential for de novo synthesis of cholesterol from acetate, but the significance of this pathway as a source of fetal or placental cholesterol in each of these species has yet to be determined.
TL;DR: It was shown that the mevalonate incorporation by the rainbow trout liver preparation into such compounds was almost quantitative, if only one enantiomorph of DL-mevalonates were utilized on the pathway of cholesterogenesis.
Abstract: The biosynthesis of squalene and cholesterol from acetate-1-14C by the homogenate supernatant of carp hepatopancreas and from mevalonate-2-14C by that of rainbow trout liver was studied in vitro. The incubation was carried out with the addition of ATP, NAD, NADH, NADP and NADPH for four hours in the carp hepatopancreas preparation with acetate, and for two hours in the rainbow trout liver preparation with mevalonate under aerobic and anaerobic conditions at 30°C. The total radioactivities incorporated into the lipids of carp hepatopancreas preparations were less than 5% of the initial acetate, in which most of the label was found in the saponifiable fraction, whereas in the nonsaponifiable fraction the percentage radioactivities were not over 10%. Therefore, the net acetate incorporation into squalene and cholesterol does not exceed 0.5%. However, it was shown that the mevalonate incorporation by the rainbow trout liver preparation into such compounds was almost quantitative, if only one enantiomorph of DL-mevalonate were utilized on the pathway of cholesterogenesis. In general, the coenzyme requirements for cholesterol synthesis in the fish are not markedly different from those needed by land animals. As one of the cofactors required for the cyclization of squalene to lanosterol, molecular oxygen plays an important role as in the case of aerobic conditions. Moreover, the metabolic pathway from acetate or mevalonate via squalene to cholesterol and their relations as the precursor, intermediate and product are discussed.