Isolation of sterols from the marine fungus Corollospora lacera

Several marine fungi collected from the waters of Prince Edward Island, Canada, were screened for the presence of natural products exhibiting antibacterial activity. Both broths and mycelia of these fungi were studied using the bioassay-guided chromatographic separation. The 4 fractions from the extract of mycelia of Corollospora lacera exhibited weak antibacterial activity and were analyzed further. From these fractions, 2 sterols (5 alpha,8 alpha-epidioxyergosterol and 22E,24R-ergosta-7,22-diene-3beta,5 alpha,6 beta-triol) and a 3:1 mixture of linoleic and oleic acids were isolated. The presence of ergosterol was confirmed in dichloromethane extracts of mycelia of every fungus in this study and this sterol was isolated from the extract of mycelium of Corollospora lacera. Two other known compounds (5-hydroxymethylfuran-2-carbaldehyde and bis(2-ethylhexyl) phthalate), were isolated from the dichloromethane extract of mycelium of Monodictys pelagica. The phthalate was reported in the literature as a metabolite isolated from the fungi, but in our study it was proven to be an artifact of the culturing and (or) extraction procedures rather than a true fungal metabolite.     

Biophysical properties of unusual phospholipids and sterols from marine invertebrates

Liposomes composed of 1,2-di-(5Z,9Z)-5-9-hexacosadienoyl-sn-glycero-3-pho sph ocholine underwent an endothermic phase transition at 42 degrees C. Cholesterol or the marine sterols studied did not affect this transition to an appreciable extent, but rather were excluded from the phospholipid bilayers. Membranes composed of 1,2-di-(5Z,9Z)-5,9-hexacosadienoyl-sn-glycero-3-pho sph ocholine displayed very similar phase properties. Effects of the marine sterols on dipalmitoylphosphatidylcholine bilayers were also investigated.     

Minor and trace sterols from marine invertebrates 56. Novel coprostanols from the marine sponge Petrosia ficiformis

Twelve stanols possessing the rare 5 beta-dihydro nucleus have been isolated from the marine sponge Petrosia ficiformis. These stanols have not previously been encountered in any samples of P. ficiformis which we have examined and appear to be the result of bacterial metabolism of the endogenous sponge sterols.     

Minor and trace sterols in marine invertebrates. 61. Isolation and structure elucidation of new A-nor sterols from the marine sponge Phakellia aruensis

An examination of the Australian sponge Phakellia aruensis led to the isolation and identification of sterols with six different nuclei. Eight new sterols were isolated which included three delta 15-A-nor sterols, three delta 7-A-nor sterols, and two saturated A-nor sterols. Their structures were established through mass spectrometry and 1H-NMR spectral studies.     

First examination of sterols in the marine dinoflagellate genus Vulcanodinium

Vulcanodinium is an ecologically relevant dinoflagellate genus due to its production of neurotoxins known as pinnatoxins. We present here the first examination of the sterols of a Vulcanodinium rugosum isolate. Sterols are ringed lipids that assist in maintaining rigidity of cellular membranes, and the Dinophyceae are well-studied for their ability to produce a diverse array of sterols, many of which have chemotaxonomic utility. We have determined that V. rugosum produces a set of major sterols, namely cholesterol, dinosterol, 4α,24-dimethyl-5α-cholest-22E-en-3β-ol, and 4α,24-dimethyl-5α-cholestan-3β-ol, common to the Dinophyceae. However, this displayed marked differences from those studied members of the genera Scrippsiella and Peridinium, the closest phylogenetic relatives. Included in these differences is production by V. rugosum of a much lower percentage of dinostanol, a saturated form of dinosterol.     

Minor and trace sterols in marine invertebrates : VI. Occurrence and possible origins of sterols possessing unusually short hydrocarbon side chains

Sterols with biosynthetically unusually short side chains (fewer than eight carbon atoms expected for primary squalene cyclization products) have been identified in the extracts of numerous marine invertebrates. The structures of the short side chain and conventional side chain sterols have been determined for various species of Porifera and Coelenterata. Sterol structures were determined by comparison of their mass spectra and gas chromatographic retention times with those of authentic or synthetic samples. Evidence is presented supporting the natural occurrence of these compounds in the tissues of the marine invertebrates as opposed to formation by degradative processes during sample handling or laboratory work-up. The short side chain sterols were found to possess predominantly the androst-5-en-3β-ol nucleus with C-17 alkyl side chains ranging from zero to six carbon atoms. Concentrations of short side chain sterols range from trace levels to over 5% of the sterol mixture in various species. The possible origins of these short side chain sterols are evaluated in the light of current knowledge of sterol function, biosynthesis, dealkylation, microbial degradation, and autoxidation. Known sterol autoxidations are reviewed, and possible singlet oxygen and free radical mechanisms of sterol side chain autoxidation (at physiological temperatures) which may lead to sterols with shortened hydrocarbon side chain are suggested. The possible autoxidative generation of short side chain sterols from known marine sterols by the suggested mechanisms is evaluated through application of the REACT computer program. Predicted short side chains are tabulated for each parent marine sterol side chain and then compared with the compositions of the actual sterols found in the marine extracts examined. The possible natural environmental or in vivo autoxidative formation of the short side chain marine sterols is supported by these evaluations.     

Bioactive polyhydroxylated sterols from the marine sponge Haliclona crassiloba

Four new polyhydroxylated sterols, named halicrasterols A–D (1–4), together with six known analogs (5–10) were isolated from the marine sponge Haliclona crassiloba. Compounds 1 and 2 represented rare examples of steroids featuring 17(20)E-double bonds. The structures of 1–10 were elucidated by spectroscopic analysis and comparison with reported data. This is the first report of a steroid profile for this species. The antimicrobial activities of 1–10 were evaluated against a panel of bacterial and fungal strains in vitro, and compounds 4 and 9 showed moderate activity against some of the Gram-positive strains with MICs ranging from 4 to 32 μg/mL.     

Chemotaxonomic survey of sterols and fatty acids in six marine raphidophyte algae

Fatty acid and sterol profiles allowed for clear discrimination betweentheraphidophyte genera Chattonella,Heterosigma, Fibrocapsa andOlisthodiscus, but exhibited little differentiation forindividual Chattonella species(C.marina, C. antiqua and C.subsalsa). Sterol and fatty acid profiles do not support theseparation of Chattonella antiqua and C.marina as distinct species. Ecophenotypic variations in lipidprofiles were also observed between Chattonella strainsfromdifferent geographic locations. Sterol signatures which may be useful aschemotaxonomic markers were: the absence of C₂₇ sterols (cholesteroland 24-dihydrozymosterol) in Heterosigma akashiwo; thepresence of isofucosterol in Chattonella; and theoccurrence of brassicasterol, poriferasterol and fucosterol inOlisthodiscus luteus. High levels of eicosapentaenoic acid(EPA; 17-27% of fatty acids) were present in all raphidophyte species. Lipidcomposition correlated more closely to recent molecular classification ofraphidophytes than carotenoid pigments.     

Minor and trace sterols in marine invertebrates. 62. Novel coprostanols with unusual side chains from the marine sponge Calyx nicaeensis

Seventeen stanols with a variety of unusual side chains and possessing the rare 5 beta-dihydro nucleus have been isolated from the sponge Calyx nicaeensis. These stanols probably result from bacterial metabolism of the endogenous sponge sterols.     

Bendigoles D-F, bioactive sterols from the marine sponge-derived Actinomadura sp. SBMs009

Marine derived actinomycetes have become an important source of bioactive natural products. Here we report the structure and bioactivity of the bendigoles D-F (1-3), 3-keto sterols isolated from the new marine sponge derived bacterium, Actinomadura sp. SBMs009. The isolation of these compounds was guided by a novel high-content screen for NF-κB and glucocorticoid receptor (GR) activity, and cytotoxicity assays. The structures of 1-3 were determined by detailed analysis of NMR, MS, and single crystal X-ray diffraction data. Interestingly, 1 displayed cytotoxicity against the L929 (mouse fibroblast) cell line with an IC(50) approximated to 30 μM and was the most active inhibitor of GR-translocation, while 3 was the most effective inhibitor of NF-κB nuclear translocation with an IC(50) of 71 μM.     

Cyclopropane-containing sterols in the marine sponge Petrosia spheroïda

The sterols of the sponge Petrosia spheroïda collected in the Indian Ocean, were isolated by liquid chromatography and reverse-phase HPLC. Sterols were characterized by GC, GC–MS and in some cases by ¹H- and ¹³C-NMR. P. spheroïda contained seven Δ⁵-unsaturated steroids with various C₈–C₁₀ side chains including petrosterol and 23,24-dihydrocalysterol, two cyclopropane-containing sterols. Chemotaxonomic considerations about the genus Petrosia are discussed.     

New polyhydroxylated sterols stylisterols A-C and a novel 5,19-cyclosterol hatomasterol from the Okinawan marine sponge Stylissa sp

New polyhydroxylated sterols, stylisterol A-C (1-3), and a novel 5,19-cyclosterol, hatomasterol (4) were isolated from the Okinawan sponge Stylissa sp. Structural determinations of these compounds were made by spectroscopic analysis and chemical conversion. Assessment of cytotoxicity toward HeLa cells was also determined.     

Minor and trace sterols in marine invertebrates 65. 23-Epidihydrocalysterol: a new cyclopropane-containing sponge sterol.

A new cyclopropane-containing sterol was isolated from the marine sponge Cribrochalina vasculum. The new sterol was characterized by nuclear magnetic resonance and mass spectrometry and the structure was shown to be (23R,24S,28R)-dihydrocalysterol. Implications concerning the biosynthesis of cyclopropane and cyclopropene sterols in sponges are discussed.     

Minor and trace sterols in marine invertebrates. 1. General methods of analysis.

3beta-Hydroxy sterols occurring at a concentration of at least 0.001% of the sterol mixtures of Pseudoplexaura porosa and Plexaura homomalla have been fractionated using a series of refined techniques and subsequently analyzed using combined gas chromatography-mass spectrometry (GC-MS) in the development of a procedure for examining the minor and trace components of marine sterol mixtures. A total of 49 sterols were found which spanned a molecular weight range of 274 to 440. In addition delta4-3-keto analogs of cholesterol, 24-methylcholesterol and gorgosterol were found in the extracts of P. homomalla. Initial separation of various natural sterol-containing conjugates and free sterols was found to have a number of advantages. Fractional digitonin precipitation and alumina column chromatography were found to possess greater sterol separation abilities than previously recognized. Many of the minor sterols were found to possess novel structures including a series of short side chain sterols, 19-nor sterols, 5beta-stanols and 4-monomethyl sterols for which structure elucidation work is continuing.     

Isolation of five new 5 alpha-hydroxy-6-keto-delta 7 sterols from the marine sponge Oscarella lobularis

Five novel sterols isolated from the marine sponge Oscarella lobularis have been identified on the basis of spectral arguments: cholest-7-ene-3beta,5alpha-diol-6-one (1), cholesta-7,22E-diene-3beta, 5alpha-diol-6-one (2), 24-methylcholesta-7,22E-diene-3beta,5alpha-diol-6-one (3), 24-methylcholesta-7,24(28)-diene-3beta,5alpha-diol-6-one (4), and 24-ethylcholest-7-ene-3beta,5alpha-diol-6-one (5).     

Configuration at C-24 of sterols from the marine phanerogames Posidonia oceanica and Cymodocea nodosa

Sterols were extracted from two marine phanerogames, Posidonia oceanica and Cymodocea nodosa. The two plants contain 24α-ethyl sterols, while the 24α-methyl sterols are accompanied by 24β-epimers. The most abundant components are sitosterol, cholesterol and stigmasterol.     

Minor and trace sterols from marine invertebrates 28. A novel polyhydroxylated sterol from the soft coral Anthelia glauca

A novel sterol containing four hydroxy groups has been isolated from the soft coral $\text{Anthelia glauca.}$ Its structure, 5α-ergostane-3β, 5,6β,7β-tetrol ($\text{1}$), has been deduced by spectroscopic methods and confirmed by comparison with a synthetic analog.     

Some studies on the biosynthesis of ubiquinone, isoprenoid alcohols, squalene and sterols by marine invertebrates

The ability of fourteen marine invertebrates to utilize [(14)C]mevalonate for the biosynthesis of isoprenoid compounds was investigated. Several of the animals, in particular crustaceans, bivalve molluscs, a coelenterate and a sponge, were unable to synthesize squalene and sterols, whereas gastropod molluscs, echinoderms, an annelid and a sponge could. Regardless of sterol-synthesizing ability the animals (with the exception of a sponge) always made dolichol and ubiquinone, and thus a specific block in squalene and sterol synthesis was indicated in some animals. Radioactivity accumulated in relatively large amounts in farnesol and geranylgeraniol in those animals incapable of making sterols.