Showing papers on "Lanosterol published in 1971"
TL;DR: Observations made in vivo with an alga and with tissue cultures of an angiosperm indicate that lanosta-8,24-dien-3β-ol (lanosterol) and its 9,19-cyclo derivative (cycloartenol) are both acceptable precursors in the biosynthesis of the major sterols of photosynthetic organisms.
46 citations
TL;DR: Squalene, squalene-2,3-oxide, triterpenes and 4α-methylsterols of Euglena gracilis Z. have been characterised by thin-layer chromatography, gas chromatography and mass spectrometry, finding the distribution in dark-grown and light-grown EuglENA cells is quantitatively and qualitatively different, reflecting differences in the sterol compositions.
Abstract: Squalene, squalene-2,3-oxide, triterpenes and 4α-methylsterols of Euglena gracilis Z. have been characterised by thin-layer chromatography, gas chromatography and mass spectrometry. Their distribution in dark-grown and light-grown Euglena cells is quantitatively and qualitatively different, reflecting differences in the sterol compositions. However the sterol precursor is found to be in each case cycloartenol, whereas lanosterol is not detected. A new 4α-methylsterol is isolated and the structure of 4α-24-dimethyl-5α-cholesta-8(9)-en-3s-ol proposed. 24-Methylene lanostenol is formed in light-grown Euglena. None of the compounds described have been found in water-soluble fractions nor in the form of fatty-acid esters. The following compounds have also been isolated: 24-methylene cycloartanol, 24-methylene agnostenol (?), s-amyrin, obtusifoliol, 24-methylene lophenol and 4α-methylzymosterol.
41 citations
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TL;DR: The sterols of the bean of the coffee tree ( Coffea arabica L.) have been identified as cycloartenol, 24-methylenecyloartanol, cycloeucalenol, obtusifoliol, citrostadienol, and campestanol as mentioned in this paper.
31 citations
TL;DR: It was shown that 100mug quantities of 4,4'-dimethyl[2-(3)H(2)]cholesta-8,14-dien-3beta-ol (IIIa) and related compounds, tritiated, were converted by a 10000g supernatant of rat liver homogenate into cholesterol in 17, 54, 6, 9.5% and 24% yields respectively.
Abstract: It was shown that 100μg quantities of 4,4′-dimethyl[2-3H2]cholesta-8,14-dien-3β-ol (IIIa), tritiated cholesta-8,14-dien-3β-ol, 4,4′-dimethyl[2-3H2]cholesta-7,14-dien-3β-ol, dihydro[2-3H2]lanosterol and [24-3H]lanosterol were converted by a 10000g supernatant of rat liver homogenate into cholesterol in 17%, 54%, 6%, 9.5% and 24% yields respectively. From an incubation of dihydro[3α-3H]lanosterol with a rat liver homogenate in the presence of a trap up to 38% of the radioactivity was found to be associated with a fraction that was unambiguously shown to be 4,4′-dimethylcholesta-8,14-dien-3β-ol. Another related compound, 4,4′-dimethylcholesta-7,14-dien-3β-ol was also shown to be equally effective in its ability to trap compound (IIIa) from an incubation of dihydro[3α-3H]lanosterol. The mechanism of the further conversion of the compound (IIIa) into cholesterol occurred by the reduction of the 14,15-double bond and involved the addition of a hydrogen atom from the medium to C-15 and another from the 4-position of NADPH to C-14. Two possible mechanisms for the removal of the 14α-methyl group in sterol biosynthesis are discussed.
28 citations
TL;DR: These compounds were efficiently incorporated by cultures of Ochromonas malhamensis into poriferasterol, the major sterol of this organism, and the significance of these results is discussed in relation to phytosterol biosynthesis.
27 citations
TL;DR: The diunsaturated methyl sterols had a larger degree of labeling than the monounsaturatedmethyl sterols in the experiments involving incubation of labeled mevalonic acid with minced tissue preparations, and cholesterol was not found to be significantly labeled.
22 citations
TL;DR: Eburicodiol and eburical as well as previously reported eburicol have been isolated from the neutral chloroform extracts of Formes officinalis and a triterpenic acid, identified as sulphurenic acid, has also been isolated as mentioned in this paper.
19 citations
TL;DR: Glial-enriched fractions were shown to synthesize sterol from [2- 14 C] mevalonic acid, and labeled squalene and lanosterol were identified in the neutral fraction from glial- enriched incubations.
19 citations
TL;DR: In this article, the hydride shifts accompanying 2,3-epoxysqualene cyclisation to lanosterol in yeast and to β-amyrin in peas have been checked using 2, 3-epoxy[11, 14-3H2]squalene.
Abstract: The hydride shifts accompanying 2,3-epoxysqualene cyclisation to lanosterol in yeast and to β-amyrin in peas have been checked using 2,3-epoxy[11,14-3H2]squalene. The results support the Ruzicka–Eschenmoser hypothesis and not a plausible alternative which was considered. The synthesis of 2,3-epoxy[11,14-3H2]squalene by two routes is described.
17 citations
TL;DR: The synthesis of nonsaponifiable compounds from radioactive mevalonate by segments of adult rat aorta was studied in vitro and it was shown that squalene and lanosterol became labeled before the other nonsaponable compounds.
16 citations
TL;DR: The in vivo conversion, by the myxomycete, of differently labelled lanosterol, stigmastanol, and 5′-stigmast-22-en-3β-ol, into the sterols 12a 11a is described and the possible biosynthetic routes for the two sterols are discussed.
Abstract: Several laboratiories have shown that the two carbon atoms C-28 and C-29 of the ethyl or ethylidene side chains of phytosterols are introduced on to a C-24 unsaturated side chain by two methylation steps. A scheme based on previous work suggests the various intermediates which can be formed by stabilisation of the carbonium ion 3. We have shown previously that in the biosynthesis of 5′-stigmastan-3β-ol (11a) and 5′-stigmast-22-en-3β-ol (12a), sterols of the myxomycete Dictyostelium discoideum, routes h and i could be excluded.
In the present paper we describe the in vivo conversion, by the myxomycete, of differently labelled lanosterol (13), stigmastanol (11), and 5′-stigmast-22-en-3β-ol (12), into the sterols 12a 11a, and discuss the possible biosynthetic routes for the two sterols.
After incorporation of a mixture of [26,27-14C2]lanosterol and [24-3H]lanosterol (3H/14C = 5.60 ± 0.25), the isolated sterols 11a 12a were converted into 11b (3H/14C = 5.54 ± 0,28) and 14b (3H/14C = 5.61 ± 0.28).
By ozonisation followed by oxidation in neutral or basic medium, 12a was converted into the esters 15 (3H/14C = 5.54 ± 0.28) and 16 (3H/14C = 5.55 ± 0.3), respectively. These results show that during the C-24 methylation, H-24 is not lost; the hydrogen which is lost is located neither at C-24 nor at C-23 and must therefore be at C-25. This excludes routes a and b for sterol 12.
After incorporation of a mixture of [26,27-14C2]lanosterol and [23-3H]lanosterol (3H/14C = 4.36 ± 0.1) the isolated sterols 11a and 12a were converted into 11b (3H/14C = 4.12 ± 0.2) and 14b (3H/14C = 3.32 ± 0.14); a fraction of 12 was degraded into 15 (3H/14C = 2.28 ± 0.31) and 16 (3H/14C = 3.44 ± 0.15).
These results show that during the conversion of 13 into 12a, 50% of the H-23 atoms migrate from C-23 to C-24 and 25% remain on C-23; the other 25% are eliminated. During the conversion of 13 into 11a both H-23 atoms are retained. These results excluded route g for the two sterols. Since we have demonstrated that the conversion of 11c into 12a is possible in high yields (4.6%) with an efficiency eight times greater than the conversion of 12a into 11a, we propose that the sterol 11a is synthesized in vivoaccording to route e with migration of H-23 from C-23 to C-24. The sterol 12a is biosynthetized either by route d, f, the 22,23 double bond being introduced during the alkylation step, or by desaturation of the sterol 11a the C-22, C-23 double bond being introduced after the C-24 alkylation.
TL;DR: In vitro incorporation of sodium acetate-3H or DL-mevalonic acid-2-14C into cholesterol was markedly increased in the liver homogenates from a patient with hypercholesterolemia, but it showed no difference between the patient and controls when skin, adipose tissue, bone marrow cells or leukocytes were used.
Abstract: In two cases of idiopathic hypercholesterolemia, aged 6 and 12 years, it was found that in vivo incorporation of sodium acetate-1-14C into serum cholesterol was markedly increased, but that into squalene and lanosterol in serum was less than that in controls. In vitro incorporation of sodium acetate-3H or DL-mevalonic acid-2-14C into cholesterol was markedly increased in the liver homogenates from a patient with hypercholesterolemia, but it showed no difference between the patient and controls when skin, adipose tissue, bone marrow cells or leukocytes were used.
TL;DR: Biosynthetic experiments with labeled mevalonate show that the unsaturated intermediates are preferentially labeled when compared with the corresponding saturated sterols.
Abstract: Sterol precursors of cholesterol with a double bond in the lateral chain are present in normal human brain and glioblastoma. Biosynthetic experiments with labeled mevalonate show that the unsaturated intermediates are preferentially labeled when compared with the corresponding saturated sterols. The biological role of sterols containing an 8(14) double bond is discussed.
TL;DR: The possible lanosterol precursor, 3β, 20(R)-dihydroxy-protost-24-ene (1 a) has been prepared, in thirteen steps, from 3α-hydroxy-4α, 8, 14-trimethyl-18-nor-5α,8α, 9β, 13ξ, 14β-androstan-17-one (mixture of 2 and 3) as discussed by the authors.
Abstract: The possible lanosterol precursor, 3β, 20(R)-dihydroxy-protost-24-ene (1 a) has been prepared, in thirteen steps, from 3α-hydroxy-4α, 8, 14-trimethyl-18-nor-5α, 8α, 9β, 13ξ, 14β-androstan-17-one (mixture of 2 and 3) In vitro experiments with rat liver homogenates failed to convert 1 a to lanosterol
TL;DR: In this paper, a high-yielding four-step sequence for removal of a 4-methyl group from the model compound 4,4-di-methyl-5α-cholestan-3,one has been devised; the method has been applied to the synthesis of 4α,14α-dimethyl-5 α-choline-8-en-3-one and 4α-14α -dimethyl -5α -choline -3,11-dione from lanosterol.
Abstract: A high-yielding four-step sequence for removal of a 4-methyl group from the model compound 4,4-di-methyl-5α-cholestan-3-one has been devised; the method has been applied to the synthesis of 4α,14α-dimethyl-5α-cholest-8-en-3-one and 4α,14α-dimethyl-5α-cholestane-3,11-dione from lanosterol.
TL;DR: In this article, a series of substituted pyrazoles, isoxazoles, and furazans with the heterocyclic ring fused to the steroid ring A was used.
Abstract: Lanost-8-en-3-one has been converted, via 2-hydroxymethylenelanost-8-en-3-one, into a series of substituted pyrazoles, isoxazoles, and furazans, with the heterocyclic ring fused to the steroid ring A.
TL;DR: Comparable incubations of adrenal tissue from a young bird using the same radioactive precursors afforded similar results, with similar results on cholesterol and squalene.
Abstract: 1. 1. Cholesterol was identified as a constituent of the pineal gland of the domestic fowl using thin-layer and gas-liquid chromatography; the pineals of laying hens had a higher cholesterol content (0·55 per cent) than those from young birds (0·08 per cent). 2. 2. Pineal tissue from young birds incorporated radioactivity from [2- 14 C]- dl -mevalonic acid lactone or sodium [1- 14 C]-acetate in vitro into the unsaponifiable lipids in variable amounts; the former precursor was used preferentially. 3. 3. Chromatographic analysis of the lipids showed that radioactivity was associated with the “cholesterol”, “lanosterol” and “squalene” fractions in proportions varying according to the precursor. 4. 4. Only squalene was identified unambiguously as a biosynthetic product of the incubation of pineals with [2- 14 C]-mevalonate. Neither the “cholesterol” nor the “lanosterol” fractions gave derivatives which recrystallized to constant specific activity. 5. 5. Comparable incubations of adrenal tissue from a young bird using the same radioactive precursors afforded similar results.
TL;DR: In this article, triterpenes and sterols previously isolated from coffee oil and reported to contain lanosterol and coffeasterol have been reexamined by TLC and mass spectrometry.