The sterol constituents and Δ5,7-sterol content of some bivalve molluscs

• 1.1. The bivalve molluscs Cerastoderma edula, Chlamys opercularis, Ensis soliqua, Modiolus modiolus, Mya arenaria, Mytilus edulis and Pecten maximus contained mixtures of C₂₆-, C₂₇-, C₂₈- and C₂₉-sterols. Cholesterol, 24-methylcholesta-5,22-dien-3β-ol and 24-methylene-cholesterol were the major sterols.
• 2.2. The sterols of Cerastoderma edula, Mya arenaria and Mytilus edulis contained 6–16% of cholesta-5,24-dien-3β-ol.
• 3.3. All the molluscs contained Δ^5,7-sterols in amounts ranging from 2 to 21% of the total sterols.
• 4.4. Cholesta-5,7-dien-3β-ol and 24-methylcholesta-5,7,22-trien-3β-ol were identified in Mytilus edulis. 25-Norcholesta-5,7,22-trien-3β-ol was detected in Modiolus modiolus.

     

Δ5,7Sterols from the sponges Ircinia pipetta and Dysidea avara identification of cholesta-5,7,24-trien-3B-OL

• 1.1. Δ^5,7-sterols have been isolated as pure compounds from the marine sponges Ircinia pipetta (Dictyoceratida:Thorectidae) and Dysidea avara (Dictyoceratida:Dysideidae) by reverse phase HPLC and analyzed by GLC, u.v., mass spectrometry and ¹H-NMR.
• 2.2. Ircinia pipetta and D. avara have rather similar sterol compositions and contain predominantly Δ^5,7-sterols, accompaned by Δ⁵-sterols. Ergosterol, cholesta-5,7-dien-3β-ol and 24-ethylcholesta-5,7-dien-3β-ol are the major sterols in I. pipetta, while D. avara contains in addition to these three sterols, (24Z)-24-ethylcholesta-5,7,24(28)-trien-3β-ol as the fourth major sterol.
• 3.3. Cholesta-5,7,24-trien-3β-ol which previously was not isolated from a marine organism is also present.

     

Sterol composition of three marine sponge species from the genus Cinachyrella

• 1.1. The hitherto undescribed sterol compositions of three marine sponge species belonging to the genus Cinachyrella are reported: C. alloclada and C. kükenthali from the Senegalese coast, at two different depths, and C. aff. schulzei from the lagoon of Nouméa, New Caledonia.
• 2.2. Fourteen free sterols have been identified by GC and GC/MS studies, including the 23,24ξ-dimethylcholesta-5,22-dien-3β-ol (10) and the rare 24-norcholesta-5,22-dien-3β-ol (1).
• 3.3. The first compound (10) is reported for the second time in a marine sponge and it was found only in Senegalese sponges collected in shallow waters.
• 4.4. Sterol (10) has been isolated by HPLC and identified by NMR techniques.
• 5.5. Significant amounts of cholest-7-en-3β-ol (7) were also found in the Senegalese sponge species.
• 6.6. Apart from these two compounds, the three sponge sterol compositions are found to be very similar.

     

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.     

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.     

Sterol composition of the “living fossil” crinoid Gymnocrinus richeri

• 1.1. The composition of sterol mixture from the “living fossil” crinoid Gymnocrinus richeri collected off Nouméa (New Caledonia) was investigated.
• 2.2. The free 3β-OH sterol mixture was found to contain 14 components, Δ⁵ and ring saturated stanols, identified by GC-MS.
• 3.3. Cholest-4-en-3-one, cholesta-1, 4-dien-3-one (this latter firstly isolated from a marine source), 5α-8α-epidioxy sterols, and 5α-ergosta-7,22-diene-3β,5,6β-triol were also present, their characterization being accomplished by EI-MS and ¹H-NMR. The methanol extract also contained sterol sulphates, which were identified by GC-MS after solvolysis to remove the sulphate group.

     

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.     

Sterol composition of Linneus torquatus (Nemertini) Anopla

The sterol fraction from the marine worm Linneus torquatus Coe (phylum Nemertini, class Anopla, family Lineidae) has been isolated, separated by HPLC and preparative TLC on AgNO₃-impregnated silica gel, and sterols identified using GC, GC-MS and NMR spectroscopy. It was shown that the fraction contains at least 12 sterols belonging mainly to Δ^5,22, Δ^5,24(28) and Δ⁵ series. The major sterol components were 24-methylcholesta-5,24(28)-dien-3β-ol, cholesta-5,22E-dien-3β-ol, 24-nor-cholesta-5,22-dien-3β-ol and cholesterol.     

Sterols of the unicellular algae Nematochrysopsis roscoffensis and Chrysotila lamellosa: isolation of (24E)-24-n-propylidenecholesterol and 24-n-propylcholesterol

Two rare C₃₀-sterols, (24E)-24-n-propylidenecholest-5-en-3β-ol and 24-n-propylcholest-5-en-3β-ol, and (24S)-24-ethylcholesta-5,22-dien- 3β-ol (stigmasterol) are the major sterols of Nematochrysopsis roscoffensis, a Chrysophyte of the Sarcinochrysidales order. This unique sterol composition is different from the sterol contents of other Chrysophytes and justifies the peculiar position of the Sarcinochrysidales, which are by some characteristics morphologically and biologically related to the Phaeophyceae. The presence of (24S)-24-methylcholesta-5,22-dien-3β-ol (24-epibrassicasterol) as a major sterol in Chrysotila lamellosa is in accordance with the few previous results obtained from other Prymnesiophyceae, although the presence of the other major sterol, (24R)-24-ethylcholesta-5,22-dien-3β-ol (poriferasterol) has never been reported in these algae.     

Sterol composition of marine bivalves from the genus Macoma

• 1.1. Four members of the genus Macoma: M. Balthica, M. irus, M.;incongrua; and M. contabulata from the Japan Sea were investigated for their sterol composition.
• 2.2. Cholest-5-en-3β-ol was the most abundant sterol in all investigated animals; the other major sterols were common constituents of bivalves.
• 3.3. The observed similarity in sterol composition of the studied clams seems to be an indication of greater influence of ecological than genetic factors on sterol composition.

     

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.     

Seasonal changes in condition and lipids composition of the bivalve Macoma balthica L. from the gulf of Gdańsk (Southern Baltic)

• 1.1. The total lipids content and composition of lipid classes, their per cent in dry wt of soft tissues and level in standard animal, as well as composition of fatty acids and sterols were studied in Macoma balthica collected from three sites in the Gulf of Gdańsk, in the years, 1983–1984.
• 2.2. The increase in the content of total lipids, triacylglycerols, oleopalmitic, 16:1 and eicosapentaenoic acids, 20:5, C27 sterols (mainly cholest-5en-3β-ol), in spring and early summer and their decrease in autumn and winter were observed.
• 3.3. Content of phospholipids, sterols and hydrocarbons in the tissue dry wt of Macoma balthica remained nearly constant.

     

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.     

The pathway of the biosynthesis of non-methylene-interrupted dienoic fatty acids in molluscs

• 1.1. The metabolic fate of 1-¹⁴C-acetate administered to the marine bivalve mollusc Mytilus edulis was investigated.
• 2.2. The active incorporation of the label in 20:2 non-methylene-interrupted dienoic (NMID) fatty acids was found.
• 3.3. Acetate incorporation patterns and specific radioactivity of mussel acids suggest that 22:2Δ7,13 and 22:2/gD7,15 arose by C₂ elongation of 20:2Δ5,11 and 20:2Δ5,13 respectively.
• 4.4. The proposed pathway of NMID fatty acid biosynthesis in molluscs is discussed.

     

Biochemical and calorific content of deep-sea aspidochirotid holothurians from the northeast atlantic ocean

• 1.1. The organic composition of the body tissues of eight species of deep-sea aspidochirotid holothurian, collected between 500 and 4100m depth in the NE Atlantic Ocean, was obtained by the biochemical analysis of protein, lipid, carbohydrate and % ash.
• 2.2. The major organic class was protein with soluble lipid the major soluble fraction in the ovary. Carbohydrate values were consistently low.
• 3.3. The calorific value was significantly higher in the ovary than in the other tissues.
• 4.4. The total body calorific content for two selected species, Benthothuria funebris and Mesothuria lactea, was 25.62 and 26.24J/mg ash-free dry weight (AFDW).

     

Steroids from aquatic organisms—XII. Sterols from the antarctic sponge Homaxinella balfourensis (Ridley and Dendy)

• 1.1. The sterol composition of the sponge Homaxinella balfourensis (Ridley and Dendy) has been analysed and seven components detected.
• 2.2. These were separated by argentic column chromatography and studied by gas chromatography-mass spectrometry and by proton magnetic resonance spectroscopy.
• 3.3. It was established that the components were C₂₇, C₂₈ and C₂₉ fully saturated or side chain unsaturated stanols and colest-5-en-3β-ol as traces.

     

Spingophosphonolipids in microsomes of Diplodon delodontus. Distribution and effect on the membrane microviscosity

• 1.1. The distribution of ceramide aminoethylphosphonate (CAEP) in microsomal membranes obtained from different tissues of the bivalve mollusc Diplodon delodontus was determined.
• 2.2. The concentration of CAEP reached from 9 to 19% of the total microsomal polar lipids, depending on the kind of tissue.
• 3.3. Palmitic acid was the main fatty acid in the ceramide moiety, followed by stearic and eicosamonoenoic acids.
• 4.4. Artificial membranes were prepared with microsomal phospholipids or phospholipids plus sterols, with and without the addition of CAEP.
• 5.5. It was shown that the phosphonate confers minor mobility to the membranes. This effect is more effective when the membrane contains the natural sterols and the phospholipids are unsaturated.

     

Biosynthesis of Δ5.23 sterols in etiolated coleoptiles from Zea mays

In addition to the previously found ergosta-5, E-23-dien-3β-ol and 5α-ergosta-7, E-23-dien-3β-ol, the following Δ23 sterols have been identified in etiolated maize coleoptiles: cyclosadol, 4α, 14α-dimethyl-5α-ergosta-8, E-23-dien-3β-ol, 4α, 14α-dimethyl-9β, 19-cyclo-5α-ergosta-8, E-23-dien-3β-ol and 4α-methyl-5α-ergosta-7, E-23-dien-3β-ol. The incubation of maize coleoptile microsomes in the presence of cycloartenol and of [¹⁴C-methyl]S-adenosyl methionine gave a mixture of labelled 24-methylene cycloartanol and cyclosadol. No trace of cyclolaudenol could be detected in these conditions. It is suggested that Δ²³ sterols are products of the C-24 methyltransferase reaction and they probably do not arise from a Δ²⁴ → Δ²³ isomerization occurring at a later stage of the biosynthesis. The Δ¹³-sterols may play an intermediary role in the biosynthesis of 24-methyl sterols in this plant material.     

The fatty acid and sterol composition of two marine dinoflagellates

The fatty acid, sterol and chlorophyll pigment compositions of the marine dinoflagellates Gymnodinium wilczeki and Prorocentrum cordatum are reported. The fatty acids of both algae show a typical dinoflagellate distribution pattern with a predominance of C₁₈, C₂₀ and C₂₂ unsaturated components. The acid 18:5ω3 is present at high concentration in these two dinoflagellates. G. wilczeki contains a high proportion (93.4%) of 4-methyl-5α-stanols including 4,23,24-trimethyl-5α-cholest-22E-en-3β-ol (dinosterol), dinostanol and 4,23,24-trimethyl-5α-cholest-7-en-3β-ol reported for the first time in dinoflagellates. The role of this sterol in the biosynthesis of 5α-stanols in dinoflagellates is discussed. P. cordatum contains high concentrations of a number of δ ²⁴⁽²⁸⁾-sterols with dinosterol, 24-methylcholesta-5,24(28)-dien-3β-ol, 23,24-dimethylcholesta-5,22E-dien-3β-ol, 4,24-dimethyl-5α-cholest-24(28)-en-3β-ol and a sterol identified as either 4,23,24-trimethyl- or 4-methyl-24-ethyl-5α-cholest-24(28)-en-3β-ol present as the five major components. The role of marine dinoflagellates in the input of both 4-methyl- and 4-desmethyl-5α-stanols to marine sediments is discussed.     

Effect of fenarimol on sterol biosynthesis in suspension cultures of bramble cells

Bramble suspension cultures normally contain Δ⁵-sterols (sitosterol, campesterol and isofucosterol). When the cells were grown in a medium supplemented with fenarimol, 14α-methyl sterols accumulated. Eight 14α-methyl sterols, including two new compounds, 4α,14α-dimethyl-stigmasta-8,Z-24(28)-dien-3β-ol and 14α-methyl-stigmasta-8,Z-24(28)-dien-3β-ol, were identified. Fenarimol probably inhibited the 14α-methyl demethylation. Cell lines growing permanently in 2 fenarimol-supplemented medium were obtained.