Sterols of Agarum cribosum: desmosterol in a brown alga

The sterol composition of the cold water brown alga Agarum cribosum was determined by GC—MS. Six of the seven sterols found were identified as stigmata-5,(E)-24(28)-dien-3β-ol (fucosterol), 24-methylenecholest-5-en-3β-ol (24-methylenecholesterol), cholest-5-en-3β-ol (cholesterol), 3β-hydroxycholest-5-en-24-one (24-ketocholesterol), 24ξ-stigmasta-5,28-diene-3β,24-diol (saringosterol) and cholesta-5, 24-dien-3β-ol (desmosterol).     

Free sterols,steryl esters,glucosides, acylated glucosides and water-soluble complexes in Calendula officinalis

In 3- and 14-day-old seedlings and in the leaves of Calendula officinalis the following sterols were identified: cholestanol, campestanol, stigmastanol, cholest-7-en-3-β-ol, 24-methylcholest-7-en-3β-ol, stigmast-7-en-3β-ol, cholesterol, campesterol, sitosterol, 24-methylcholesta-5,22-dien-3β-ol, 24-methylenecholesterol, stigmasterol and clerosterol. Sitosterol was predominant in young and stigmasterol in old tissues. Young tissues contained relatively more campesterol but in old tissues a C₂₈Δ^5,22 diene was present suggesting transformation of campesterol to its Δ^5,22 analog, similar to that of sitosterol to stigmasterol. All the identified sterols were present as free compounds and also in the steryl esters, glucosides, acylated glucosides and water-soluble complexes. The variations in the amounts of these fractions in the embryo axes and cotyledons of 3- and 14-day-old seedlings and the distribution of individual sterols among the fractions are discussed.     

Free sterols of the red alga Gigartina skottsbergii

The free sterols of the red alga Gigartina skottsbergii have been identified by means of GC and GC/MS analyses. The mixture contained saturated and unsaturated C²⁷, C²⁸ and C²⁹ sterols. The major component was cholest-5-en-3β-ol. Cholesta-5,24-dien-3β-ol (desmosterol) was present in low proportion but no side chain hydroxylated components were detected.     

Analysis of sterols in selected bloom-forming algae in China

Sterols, a group of stable lipid compounds, are often used as biomarkers in marine biogeochemical studies to indicate sources of organic matter. In this study, sterols in 13 species of major bloom-forming algae in China, which belong to Dinophyceae, Bacillariophyceae, Ulvophyceae, and Pelagophyceae, were analyzed with gas chromatography-mass spectrometry (GC–MS) to test their feasibility in representing different types of harmful algal blooms (HABs). It was found that (24Z)-stigmasta-5,24-dien-3β-ol (28-isofucosterol) was a major sterol component in green-tide forming macroalga Ulva prolifera. In bloom-forming dinoflagellates Alexandrium spp., Prorocentrum micans and Scrippsiella trochoidea, (22E)-4α,23-dimethyl-5α-ergost-22-en-3β-ol (dinosterol) was detected in addition to cholest-5-en-3β-ol (cholesterol), (22E)-ergosta-5,22-dien-3β-ol, (22E)-stigmasta-5,22-dien-3β-ol and other minor sterol components. In brown-tide forming pelagophyte Aureococcus anophagefferens, (24E)-24-propylcholesta-5,24-dien-3β-ol ((24E)-24-propylidenecholesterol) and (24Z)-24-propylcholesta-5,24-dien-3β-ol ((24Z)-24-propylidenecholesterol) were detected together with cholesterol, (22E)-stigmasta-5,22-dien-3β-ol, stigmast-5-en-3β-ol and campest-5-en-3β-ol. Among the selected bloom-forming diatoms, Chaetoceros sp. and Pseudo-nitzschia spp. only produced cholesterol, while Cylindrotheca closterium produced solely (22E)-ergosta-5,22-dien-3β-ol. Sterol content in four bloom-forming algal species correlates well with their biomass or abundance. It's proposed that 28-isofucosterol could serve as a promising biomarker for green algae in green-tide studies. Dinosterol and (24Z)-24-propylidenecholesterol can be used as potential biomarkers to represent bloom-forming dinoflagellates and pelagophytes, while (22E)-ergosta-5,22-dien-3β-ol is not a good indicator for diatoms.     

The identification of 24-methylene-24,25-dihydrolanosterol and other possible ergosterol precursors in Phycomyces blakesleeanus and Agaricus campestris

The following sterols have been isolated from the fungi, Phycomyces blakesleeanus and Agaricus campestris: ergosterol, lanosterol, 24-methylene-24,25-dihydrolanosterol and episterol. 4,4-Dimethyl-5α-ergosta-8.24(28)-dien-3β-ol and 4α-methyl-5α-ergosta-8,24(28)-dien-3β-ol have been tentatively identified. Evidence for the incorporation of label from l-methionine-[methyl-¹⁴C] into some of these sterols in P. blakesleeanus has been obtained. The significance of these sterols in ergosterol biosynthesis is discussed.     

In vitro inhibition of rat liver cholest-5en-3 beta-ol (cholesterol) biosynthesis by non-mercurial sulfhydryl reagents.

In vitro conversion of 2-14C-mevalonate to cholest-5en-3 beta-ol (cholesterol) in rat liver homogenates is inhibited by arsenite, beta-mercaptoethanol, dithiothreitol and ethanethiol. Two sterols containing 20 carbon atoms accumulate under these conditions. One of these is identified as 4,4 dimethyl-5alpha-cholest-8en-3beta-ol and the other tentatively identified as 4,4 dimethyl-5alpha-cholest-8,24-dien-3beta-ol. Based on these observations, these non-mercurial sulfhydryl reagents do not inhibit 5alpha-lanosta-8,24-dien-3beta-ol 14alpha demethylase.     

Dinoflagellate sterols IV: Isolation and structure of 4α,23ξ,24ξ-trimethylcholestanol from the dinoflagellate Glenodiniumhallii

The dinoflagellate $\text{Glenodinium}$$\text{hallii}$ was investigated for its sterol composition. Five of the six sterols were isolated and identified as cholest-5-en-3β-ol, (24ξ)-24-methylcholest-5-en-3β-ol, stigmasta-5,22-dien-3β-ol, (22E,24R)-4α,23,24-trimethyl-5α-cholest-22-en-3β-ol, and 4α,23ξ,24ξ-trimethyl-5α-cholestan-3β-ol.     

Dominance of Δ5-sterols in eight species of the cactaceae

The sterols from eight species in seven genera of the Cactaceae are 24-alkyl-Δ⁵-sterols. In all eight species, Echinopsis tubiflora, Pereskia aculeata, Hylocereus undatus, Notocactus scopa, Epiphyllum sp., Schlumbergera bridgesii, Opuntia comonduensis and O. humifusa, the dominant sterol is sitosterol (24α-ethylcholest-5-en-3β-ol) at 66–87% of the total sterol composition with the 24ξ-methylcholest-5-en-3β-ol present at 8–33%. Stigmasterol (24α-ethylcholesta-5,22E-dien-3β-ol) is present at 2–8% of the total sterol in P. aculeata, H. undatus, N. scopa and Epiphyllum sp. whereas cholesterol (cholest-5-en-3β-ol) is present in six species at levels of <0.1–5.0%. Avenasterol (24-ethylcholesta-7,24(28)Z-dien-3/gb-ol) and sitostanol (24α-ethyl-5α-cholestan-3β-ol) are each present in two species.     

EFFECT OF ZUCLOMIPHENE ON CHOLESTEROL FORMATION IN THE DEVELOPING CENTRAL NERVOUS SYSTEM OF THE RAT

Abstract— The effect of zuclomiphene, a hypocholesterolemic agent, on developing rat CNS cholesterol biosynthesis was examined. Sterol content and composition was studied in relation to age in four regions of the CNS, cerebrum, brain stem, spinal cord and cerebellum. Sterol content of all four regions was slightly lower in drug-treated animals than in controls. Brain stem and spinal cord were more susceptible to the effects of zuclomiphene than were cerebrum and cerebellum. Drug treatment resulted in the accumulation of desmosterol and zymosterol (5 x -cholesta-8,24-dien-3β-ol) in all CNS regions. After 15 days of drug treatment, desmosterol constituted more than 50% of the total sterol in the four examined regions. Six to 9% of the total sterol was zymosterol.
Examination by electron microscopy indicated only minimal morphological changes. Occasionally, neuronal membranous cytoplasmic inclusion bodies were evident.     

STEROLS OF 14 SPECIES OF MARINE DIATOMS (BACILLARIOPHYTA)1

The sterol compositions of 14 species of marine diatoms were determined by gas chromatography and gas chromatography-mass spectrometry. A variety of sterol profiles were found. The sterols 24-methylcholesta-5,22E-dien-3β-ol, cholest-5-en-3β-ol, and 24-methylcholesta-5,24(28)-dien-3β-ol, previously described as the most common sterols found in diatoms, were major sterols in only a few of the species. In light of this and other recent data, it is clear that these three sterols are not typical constituents of many diatom species. Most of the centric species examined had 24-methylcholesta-5,24(28)-dien-3β-ol and 24-methylcholest-5-en-3β-ol as two of their major sterols. The exception was Rhizosolenia setigera, which possessed cholesta-5,24-dien-3β-ol as its single major sterol. In contrast to the centric species, the pennate diatoms examined did not have any particular sterols common to most species. Minor levels ofΔ⁷-sterols, rarely found in large amounts in diatoms, were found in four species. C₂₉sterols were found in many species; seven contained 24-ethylcholest-5-en-3β-ol and three contained 24-ethylcholesta-5,22E-dien-3β-ol, reinforcing previous suggestions that C₂₉ sterols are not restricted to higher plants and macroalgae. 24-Ethylcholesta-5,22E-dien-3β-ol may prove to be useful for taxonomy of the genus Amphora and the order Thalassiophysales. A major sterol of Fragilaria pinnata was the uncommon algal sterol 23,24-dimethylcholesta-5,22E-dien-3β-ol. Cholesta-5,24-dien-3β-ol was the only sterol found in the culture of Nitzschia closterium. This differed from previous reports of 24-methylcholesta-5,22E-dien-3β-ol as the single major sterol in N. closterium. Two C₂₈ sterols possessing an unusual side chain were found in Thalassi-onema nitzschioides, a C_28:2 sterol (16%) and a C_28:1 sterol in lower abundance (2.5%), which may be 23-methylcholesta-5,22E-dien-3β-ol and 23-methyl-5α-cholest-22E-en-3β-ol, respectively. The species Cylindrotheca fusiformis, T. nitzschioides, and Skeletonema sp. may be useful as direct sources of cholesterol in mariculture feeds due to their moderate to high content of this sterol.     

Sterols of morphologically distinct,okadaic acid-producing Prorocentrum texanum var. texanum and var. cuspidatum isolated from the Gulf of Mexico

Prorocentrum texanum var. texanum and its morphologically distinct yet genetically identical (as based on the sequences of five genes) variety P. texanum var. cuspidatum represent a species of Prorocentrum recently isolated from the Gulf of Mexico. Together, these two varieties represent a sister species to Prorocentrum micans. P. micans has had its sterols, which are ringed lipids common to eukaryotic cell membranes, shown in some studies to be comprised of cholesterol (cholest-5-en-3β-ol), 23,24-dimethyl-cholesta-5,22-dien-3β-ol, 23,24-dimethyl-5α-cholest-22E-en-3β-ol, dinosterol, and 4α,23,24-trimethyl-5α-cholestan-3β-ol (dinostanol) as major sterols, thus placing it within a previously identified cluster of dinoflagellates characterized by the predominance of cholesterol and dinosterol. In this study we have determined the sterol compositions of these two varieties of P. texanum to be abundant in cholesterol, 23,24-dimethyl-cholesta-5,22-dien-3β-ol, 23,24-dimethyl-5α-cholest-22E-en-3β-ol, dinosterol, and dinostanol such that the varieties are virtually indistinguishable from each other, making them both in general agreement with the sterols of P. micans, its closest species relative. This expands our knowledge of the sterols of this environmentally important dinoflagellate genus.     

Investigations on the Δ23-, Δ24(28)- and Δ25-Sterols of zea mays

The sterols of Zea mays shoots were isolated and characterized by TLC, HPLC, GC/MS and ¹H NMR techniques. In all, 22 4-demethyl sterols were identified and they included trace amounts of the Δ²³-, Δ²⁴- and Δ²⁵-sterols, 24-methylcholesta-5,E-23-dien-3β-ol, 24-methylcholesta-5,Z-23-dien-3β-ol, 24-methylcholesta-5,25-dien-3β-ol, 24-ethylcholesta-5,25-dien-3β-ol and 24-ethylcholesta-5,24-dien-3β-ol. In the 4,4-dimethyl sterol fraction, cycloartenol and 24-methylenecycloartanol were the major sterol components but small amounts of the Δ²³-compound, cyclosadol, and the Δ²⁵-compound, cyclolaudenol, were recognized. These various Δ²³- and Δ²⁵-sterols may have some importance in alternative biosynthetic routes to the major sterols, particularly the 24β-methylcholest-5-en-3β-ol component of the C₂₈-sterols. Radioactivity from both [2-¹⁴C]MVA and [methyl-¹⁴C]methionine was incorporated by Z. mays shoots into the sterol mixture. Although 24-methylene and 24-ethylidene sterols were relatively highly labelled, the various Δ²³- and Δ²⁵-sterols contained much lower levels of radioactivity, which is possibly indicative of their participation in alternative sterol biosynthetic routes. (24R)-24-Ethylcholest-5-en-3β-ol (sitosterol) had a significantly higher specific activity than the 24-methylcholest-5-en-3β-ol indicating that the former is synthesized at a faster rate.     

Dehydrodinosterol,dinosterone and related sterols of a non-photosynthetic dinoflagellate, Crypthecodinium cohnii

The heterotrophic dinoflagellate Crypthecodinium cohnii contained the 4α-methyl sterols, dinosterol, dehydrodinosterol (4α,23,24-trimethylcholesta-5,22-dien-3β-ol) and the tentatively identified 4α,24-dimethyl-cholestan-3β-ol and 4α,24-dimethylcholest-5-en-3β-ol. The major 4-demethyl sterol was cholesta-5,7-dien-3β-ol which was accompanied by a smaller amount of cholesterol and traces of several other C₂₇,C₂₈ and C₂₉ sterols. In addition, a 3-oxo-steroid fraction was isolated and the major component identified as dinosterone (4α,23,24-trimethylcholest-22-en-3-one). The possible biosynthetic relationships of these compounds are discussed.     

Distribution pattern of sterols in liverworts belonging to the jungermanniineae

The sterol fractions of eight leafy liverworts were analyzed by GLC and GC-MS. Five 3β-sterols, cholest-5-en-3β-ol, 24-methylcholest-5,22-dien-3β-ol, 24-methylcholest-5-en-3p-ol, 24-ethylcholest-5,22-dien-3β-ol and 24-ethylcholest-5-en-3β-ol, were detected in all samples but there were differences in the relative amounts present.     

Sterols of Mediterranean Florideophyceae

The distribution of sterols in 31 Mediterranean Florideophyceae has been investigated. Cholesterol is present in the greatest majority of the species examined, while the occurrence of other C-27 sterols (desmosterol, 22-dehydrocholesterol, liagosterol and cholest-7-en-3β-ol) is much more restricted. Two species (Rytiphloea tinctoria and Vidalia volubilis) contain, in addition to C-27 sterols, large amounts of C-28 and C-29 compounds.     

Sterol profiles of red algae

Twelve species of red algae belonging to the Orders Gelidiales, Cryptonemiales and Gigartinales were examined for sterols. Four species contained cholestan-3β-ol as the major sterol, accompanied by C₂₆, C₂₈ and C₂₉ stanols. Sterols not previously reported in algae were 24-dimethyl-5α-chol-22-en-3β-ol, cholest-22-en-3β-ol, cholest-7-en-3β-ol, 24ξ-methylcholest-22-en-3β-ol, 24-methylenecholestan-3β-ol, 24ξ-ethylcholestan-3β-ol and isofucostanol.     

Free Sterols of the Rabbit Optic Nerve and Cerebral White Matter During Ontogenic Development

Abstract: Free sterol composition of the developing rabbit optic nerve was compared with that of the homologous cerebral white matter at corresponding stages of ontogeny. The sterols were detected and identified by means of combined gas-chromatography and mass spectrometry. The following free sterols were found in both the optic nerve and cerebral white matter: cholesterol, desmosterol, lanosterol, two dimethylsterols, which are probably 4,4-dimethyl-5α-cholest-8,24-diene-3β-ol, with a molecular weight of 412, and 4α,14α-dirnethyl-5α-cholest-7-ene-3β-ol, with a molecular weight of 414 and probably cholestene, with a molecular weight of 368. The sterol spectrum of the developing optic nerve differed not only from that of the mature nerve but also from that of age-matched white matter of the rabbit brain. The tri- and dimethyl-sterols, detected for the first time in the rabbit optic nerve and cerebral white matter, are natural components of the developing nervous tissue but they were not found in the mature nerve nor in cerebral white matter.     

Sterols and fatty acids of the marine diatom biddulphia sinensis

Nine sterols, most showing Δ⁵- or Δ^5,22-unsaturation, were identified in the marine diatom Biddulphia sinensis. One sterol, cholesta-5,22E-dien-3β-ol, comprised 70–80% of the total sterols which is the first such predominance noted in a diatom. The only Δ⁷-sterol detected was cholest-7-en-3β-ol and this was a very minor component. A sterol showing unusual side-chain alkylation,23,24-dimethylcholesta-5,22E-dien-3β-ol, was identified for the first time in a diatom. Total fatty acids exhibited a predominance of Δ⁹- 16:1, 14:0, 20:5 and 16:0, typical of diatoms, although the proportions of these acids were found to vary with culture maturity. n-Heneicosahexaene was the major hydrocarbon together with a small amount of squalene.     

Sterols of Amphidinium species in the Operculatum Clade: Predominance of cholesterol instead of Δ8(14) sterols previously considered Amphidinium-specific biomarkers

The dinoflagellates Amphidinium carterae and Amphidinium corpulentum have been previously characterized as having Δ⁸⁽¹⁴⁾-nuclear unsaturated 4α-methyl-5α-cholest-8(14)-en-3β-ol (C_28:1) and 4α-methyl-5α-ergosta-8(14),24(28)-dien-3β-ol (amphisterol; C_29:2) as predominant sterols, where they comprise approximately 80% of the total sterol composition. These two sterols have hence been considered as possible major sterol biomarkers for the genus. Here, we have examined the sterols of four recently identified species of Amphidinium (Amphidinium fijiense, Amphidinium magnum, Amphidinium theodori, and Amphidinium tomasii) that are closely related to Amphidinium operculatum as part of what is termed the Operculatum Clade to show that each species has its sterol composition dominated by the common dinoflagellate sterol cholesterol (cholest-5-en-3β-ol; C_27:1), which is found in many other dinoflagellate genera, rather than Δ⁸⁽¹⁴⁾ sterols. While the Δ⁸⁽¹⁴⁾ sterols 4α-methyl-5α-cholest-8(14)-en-3β-ol and 4α,23,24-trimethyl-5α-cholest-8(14),22E-dien-3β-ol (C_30:2) were present as minor sterols along with another common dinoflagellate sterol, 4α,23,24-trimethyl-5α-cholest-22E-en-3β-ol (dinosterol; C_30:1), in some of these four species, amphisterol was not conclusively observed. From a chemotaxonomic perspective, while this does reinforce the genus Amphidinium's ability to produce Δ⁸⁽¹⁴⁾ sterols, albeit here as minor sterols, these results demonstrate that caution should be used when considering Δ⁸⁽¹⁴⁾ sterols, especially amphisterol, as Amphidinium-specific biomarkers within these species where cholesterol is the predominant sterol.     

Minor and trace sterols in marine invertebrates V. isolation,structure elucidation and synthesis of 3β-hydroxy-26,27-bisnorcholest-5-en-24-one from the sponge Psammaplysilla Purpurea

The free sterol mixture of the sponge Psammaplysilla purpurea was shown to contain aplysterol as the major constituent. In addition to other sterols such as 5,7-cholestadien-3β-ol, cholesterol, 5α-cholestan-3β-ol, 24ε-methylcholesta-5,22-dien-3β-ol, 24ε-methylcholesterol, 24ε-ethylcholesta-5,22-dien-3β-ol and 24,28-dehydroaplysterol, a new minor sterol was isolated and shown by spectral analysis as well as partial synthesis to be 3β-hydroxy-26,27-bisnorcholest-5-en-24-one. The sterol mixture contains no other short side chain or 24-keto sterols except for small amounts of 3β-hydroxypregn-5-en-20-one and 3β-hydroxy-5α-pregnan-20-one.