Sterol Glycosides Research Articles

Triterpenoidal Saponins: Bioactive Secondary Metabolites fromZygophyllum coccineum

Phytochemical investigation of the aerial parts of Zygophyllum coccineum L. led to the isolation of nine ursane-type triterpene saponins (1- 9), including the new one; zygophylloside S (1), together with a known flavonoid glycoside (10) and a sterol glycoside (11). The isolated compounds were tested for antifungal activity against several important plant pathogens and for insecticidal activity against two important mosquito species. Among the isolated compounds 1, 3, 5, 6, and 9 showed 32-77 % fungal growth inhibition at a concentration of 30 µM against Phomopsis viticola. Compound 9 showed 90 % and 80 % mosquitocidal activity at 3.1 µg/0.5 µL against Aedes aegypti and Culex quinquefasciatus, respectively.

Structure and biological evaluation of novel cytotoxic sterol glycosides from the marine red alga Peyssonnelia sp.

Bioactivity-guided fractionation of the extract from a Fijian red alga Peyssonnelia sp. led to the isolation of two novel sterol glycosides 19- O-β- d-glucopyranosyl-19-hydroxy-cholest-4-en-3-one ( 1) and 19- O-β- d- N-acetyl-2-aminoglucopyranosyl-19-hydroxy-cholest-4-en-3-one ( 2), and two known alkaloids indole-3-carboxaldehyde ( 3) and 3-(hydroxyacetyl)indole ( 4). Their structures were characterized by 1D and 2D NMR and mass spectral analysis. The sterol glycosides inhibited cancer cell growth with mean IC 50 values (for 11 human cancer cell lines) of 1.63 and 1.41 μM for 1 and 2, respectively. The most sensitive cancer cell lines were MDA-MB-468 (breast) and A549 (lung), with IC 50’s in of 0.71–0.97 μM for 1 and 2. Modification of the sterol glycoside structures revealed that the α,β-unsaturated ketone at C-3 and oxygenation at C-19 of 1 and 2 are crucial for anticancer activity, whereas the glucosidic group was not essential but contributed to enhanced activity against the most sensitive cell lines.

ChemInform Abstract: Brazilian Natural Medicines. Part 4. New Noroleanane‐Type Triterpene and Ecdysterone‐Type Sterol Glycosides and Melanogenesis Inhibitors from the Roots of Pfaffia glomerata.

AbstractIsolation and structural elucidation of the new norolenane‐type triterpene, pfaffianol A (Ia), related triterpene glycosides, pfaffiaglycosides A (Ib) and B (Ic), and three new ecdysterone‐type sterol glycosides, pfaffiaglycosides C (IIa), D (IIb) and E (III) are described.

Carijoside A, a Bioactive Sterol Glycoside from an Octocoral Carijoa sp. (Clavulariidae)

A new bioactive sterol glycoside, 3β-O-(3′,4′-di-O-acetyl-β-d-arabinopyranosyl) -25ξ-cholestane-3β,5α,6β,26-tetrol-26-acetate) (carijoside A, 1), was isolated from an octocoral identified as Carijoa sp. The structure of glycoside 1 was established by spectroscopic methods and by comparison with spectral data for the other known glycosides. Carijoside A (1) displayed significant inhibitory effects on superoxide anion generation and elastase release by human neutrophils and this compound exhibited moderate cytotoxicity toward DLD-1, P388D1, HL-60, and CCRF-CEM tumor cells.

Zygophylloside S, a New Triterpenoid Saponin from the Aerial Parts of Zygophyllum coccineum L.

Saponins are a vast group of glycosides with a wide range of biological activities [1]. They are believed to form the main constituents of many plant drugs and folk medicines [2]. Their pharmacological importance has motivated us to contribute to the study of Zygophyllum coccineum L., an Egyptian desert plant rich in saponins. The present work led to the isolation of one new ursane type triterpenoid saponin (1), 3-O-[α-L-arabinopyranosyl-(1→2)-β-D-glucopyranosyl] quinovic acid (zygophylloside S), in addition to eight known saponins, one flavonoid glycoside, and one sterol glycoside from the aerial parts of the plant. The structures were established mainly by 1D and 2D NMR techniques, in combination with IR and HRMS. The anti-microbial, anti-malarial, and anti-leishmanial activity of the isolated compounds are in progress.

Auroside, a Xylosyl-sterol, and Patusterol A and B, two Hydroxylated Sterols, from two Soft Corals Eleutherobia aurea and Lobophytum patulum

A new sterol glycoside, auroside (1) and two new hydroxylated sterols, patusterol A and B (2, 3) have been isolated from the South African soft coral Eleutherobia aurea and from the Kenyan soft coral Lobophytum patulum. The structure elucidation was achieved from extensive 1D- and 2D- NMR and MS data, and in the case of auroside also by chemical reactions. In addition, from Lobophytum patulum, was also isolated a known nitrogen containing compound (Z)-N-[2-(4-hydroxyphenyl)ethyl]-3-methyldodec-2-enamide, and from Eleutherobia aurea several, earlier reported, diterpenoids. Compound 2 was found to be toxic to brine shrimp embryos with an LC50 value of 2.30 microM.

Brazilian Natural Medicines. IV. New Noroleanane-Type Triterpene and Ecdysterone-Type Sterol Glycosides and Melanogenesis Inhibitors from the Roots of Pfaffia glomerata

The ethyl acetate and 1-butanol soluble fractions of the roots of Pfaffia glomerata were found to show inhibitory effects on melanogenesis in theophylline-stimulated B16 melanoma 4A5 cells. From the ethyl acetate and 1-butanol soluble fractions, we isolated a new noroleanane-type triterpene, pfaffianol A, its glycosides, pfaffiaglycosides A and B, and ecdysterone-type sterol glycosides, pfaffiaglycosides C, D, and E, together with eight known constituents. The structures of new constituents were determined on the basis of physicochemical and chemical evidence. Among them, pfaffianol A (IC(50)=44 microM) and pfaffoside C (IC(50)=92 microM) substantially inhibited melanogenesis without cytotoxic effects. The inhibitory effects were stronger than that of reference compound, arbutin (IC(50)=174 microM).

Analysis of Sterol Glycosides in Biodiesel and Biodiesel Precipitates

AbstractBiodiesel is produced by the transesterification of vegetable oils with short chain alcohols, usually in the presence of an alkali catalyst. Minor components in biodiesel exist as a result of unreacted reagents, by‐products, additives, and auto‐oxidation products, such as water, free glycerin, bonded glycerin, free fatty acids, catalysts, residual alcohol, unsaponifiable matter (plant sterols, antioxidants, and hydrocarbons), soaps and polymers. The biodiesel properties, such as cold flow properties, acid number, cetane number, and oxidative stability are oftentimes significantly affected by these minor components. Sterol glycosides, as one of the most important minor components in biodiesel, and due to their polarities and limited solubility, can accelerate precipitate formation even at room temperature and possibly block fuel filters. In this paper, reversed phase high‐performance liquid chromatography with an Evaporative Light Scattering Detector (ELSD) is evaluated for the analysis of sterol glycoside (SG) content in not only biodiesel precipitates but also in biodiesel. SG was found to be a major component in soy biodiesel precipitates and an SG peak was found in biodiesel after concentration by centrifugation.

Lipid asymmetry in plant plasma membranes: phosphate deficiency‐induced phospholipid replacement is restricted to the cytosolic leaflet

As in other eukaryotes, plant plasma membranes contain sphingolipids, phospholipids, and free sterols. In addition, plant plasma membranes also contain sterol derivatives and usually <5 mol% of a galactolipid, digalactosyldiacylglycerol (DGDG). We earlier reported that compared to fully fertilized oats (Avena sativa), oats cultivated without phosphate replaced up to 70 mol% of the root plasma membrane phospholipids with DGDG. Here, we investigated the implications of a high DGDG content on membrane properties. The phospholipid-to-DGDG replacement almost exclusively occurred in the cytosolic leaflet, where DGDG constituted up to one-third of the lipids. In the apoplastic (exoplasmic) leaflet, as well as in rafts, phospholipids were not replaced by DGDG, but by acylated sterol glycosides. Liposome studies revealed that the chain ordering in free sterol/phospholipid mixtures clearly decreased when >5 mol% DGDG was included. As both the apoplastic plasma membrane leaflet (probably the major water permeability barrier) and rafts both contain only trace amounts of DGDG, we conclude that this lipid class is not compatible with membrane functions requiring a high degree of lipid order. By not replacing phospholipids site specifically with DGDG, negative functional effects of this lipid in the plasma membrane are avoided.-Tjellström, H., Hellgren, L. I., Wieslander, A., Sandelius, A. S. Lipid asymmetry in plant plasma membranes: phosphate deficiency-induced phospholipid replacement is restricted to the cytosolic leaflet.

Lipophilic extractives from several nonwoody lignocellulosic crops (flax, hemp, sisal, abaca) and their fate during alkaline pulping and TCF/ECF bleaching

The fate of lipophilic extractives from several nonwoody species (flax, hemp, sisal and abaca) used for the manufacturing of cellulose pulps, was studied during soda/anthraquinone (AQ) pulping and totally chorine free (TCF) and elemental chlorine free (ECF) bleaching. With this purpose, the lipophilic extracts from the raw materials and their unbleached and bleached industrial pulps, were analyzed by gas chromatography–mass spectrometry. Aldehydes, hydroxyfatty acids and esterified compounds such as ester waxes, sterol esters and alkylferulates strongly decreased after soda/AQ pulping while alkanes, alcohols, free sterols and sterol glycosides survived the cooking process. Among the lipophilic extractives that remained in the unbleached pulps, some amounts of free sterols were still present in the TCF pulps whereas they were practically absent in the ECF pulps. Sterol glycosides were also removed after both TCF and ECF bleaching. By contrast, saturated fatty acids, fatty alcohols and alkanes were still present in both bleached pulps.

Chemical Constituents from Seeds of &lt;i&gt;Panax ginseng&lt;/i&gt;: Structure of New Dammarane-Type Triterpene Ketone, Panaxadione, and HPLC Comparisons of Seeds and Flesh

A new dammarane-type triterpene ketone, panaxadione, was isolated from the seeds of Panax ginseng C. A. MEYER (Araliaceae) together with two dammarane-type and lupane-type triterpenes, an aromatic oligoglycoside, three sterol glycosides, and three dammarane-type triterpene oligoglycosides (ginsenosides Rd, Re, and Rg(2)). The structure of a new compound was elucidated on the basis of physicochemical evidence. The relative contents of major ginsenosides in the seeds were compared with those of the flesh parts of young and mature fruits.

Chemical composition of lipophilic extractives from sisal ( Agave sisalana) fibers

The chemical composition of lipophilic extractives from sisal ( Agave sisalana) fibers, which are used for high-quality paper pulp production, was studied. The lipophilic extract, which accounted for 0.5% of total sisal fiber weight, was analyzed by gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS) using short- and medium-length high temperature capillary columns, respectively. For a more detailed characterization, the extract was fractionated by solid-phase extraction and the fractions obtained were analyzed by GC and GC/MS. The most predominant compounds identified were fatty acids (30% of total lipids) including α- and ω-hydroxyfatty acids, fatty alcohols (20%), free sterols (11%), alkanes (11%) and a series of ferulic acid esters of long chain alcohols and ω-hydroxyfatty acids (10%). Additionally, steroid hydrocarbons and ketones, monoglycerides, aldehydes, waxes, and sterol glycosides were also found together with minor amounts of diglycerides, and sterol esters.

Molecular cloning and characterization of one member of 3β-hydroxy sterol glucosyltransferase gene family in Withania somnifera

Sterol glycosides are constituents of plant cell membranes. Glucosylations of the sterols are catalyzed by sterol glucosyltransferases (SGTs), which are members of family 1 glycosyltransferases. We have identified the family of SGT genes expressed in the leaves of a medicinal plant Withania somnifera. One member ( SGTL1) of this gene family was cloned. The full-length cDNA sequence of SGTL1 represents 2532 bp, comprising untranslated regions (UTRs) of 337 and 89 bp at the 5′ and 3′ ends, respectively. The amino acid sequence deduced from the 2103 bp open reading frame (ORF) showed homology (67–45%) to the reported plant SGTs. The presence of two putative transmembrane domains suggested the association of SGTL1 with membrane. The SGTL1 was expressed in Escherichia coli and recombinant enzyme from the supernatant was partially purified and biochemically characterized. The relative activity and kinetic properties of SGTL1 for different sterols were compared with a recombinant SGT (GenBank Accession No. Z83833) of Arabidopsis thaliana ( AtSGT). Both the recombinant enzymes showed activity with 3-β-OH sterols. The distribution of SGTL1 transcript in W. somnifera, as determined by quantitative PCR, showed higher expression in roots and mature leaves. Expression of the SGTL1 transcript in the leaves of W. somnifera was enhanced following the application of salicylic acid. In contrast, it decreased rapidly on exposure of the plants to heat shock, suggesting functional role of the enzyme in biotic and abiotic stresses.

Total plant sterols, steryl ferulates and steryl glycosides in milling fractions of wheat and rye

The total plant sterol, steryl ferulate and steryl glycoside contents in wheat and rye milling fractions show that there are significant differences in both sterol content and composition between various milling fractions collected from a commercial mill. Total sterols were analysed by gas chromatography after acid and alkaline hydrolyses. The steryl conjugates were first extracted with acetone, fractionated on solid phase extraction (SPE) cartridges and then analysed individually (steryl glycosides by gas chromatography and steryl ferulates by reverse phase-high performance liquid chromatography with UV detection. Differences in sterol contents of the wheat samples were greater than in the rye samples. The highest total sterol content was found in wheat germ, but surprisingly high sterol contents, that were comparable to bran, were found in some flour fractions. Contents of steryl ferulates were high in the bran fractions contributing up to 17% of total sterols. The variation in the content of steryl glycosides in the samples was lower and contributed less than 10% of total sterols. These results show that much of the bioactive components may be lost when certain flour fractions produced in common flour milling procedures are discarded. However, some of these fractions with significantly high sterol contents could possibly be introduced into milling products used in breadmaking and the food industry without greatly compromising consumer acceptability.

Bacosterol Glycoside, a New 13,14‐Seco‐steroid Glycoside from Bacopa monnieri.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Chemical Composition of Abaca (Musa textilis) Leaf Fibers Used for Manufacturing of High Quality Paper Pulps

The chemical composition of leaf fibers of abaca (Musa textilis), which are commonly used for high-quality paper pulp production, was thoroughly studied. The results revealed that the lignin content was 13.2% of the total fiber. The analysis of abaca fibers by pyrolysis coupled to gas chromatography-mass spectrometry (Py-GC/MS) released predominantly compounds arising from lignin and p-hydroxycinnamic acids, with high amounts of 4-vinylphenol. The latter compound was demonstrated to arise from p-coumaric acid by pyrolysis of abaca fibers in the presence of tetramethylammonium hydroxide, which released high amounts of p-coumaric acid (as the methyl derivative). Products from p-hydroxyphenyl (H), guaiacyl (G), and syringyl (S) propanoid units, with a predominance of the latter (H:G:S molar ratio of 1.5:1:4.9), were also released after Py-GC/MS of abaca fibers. Sinapyl and coniferyl acetates, which are thought to be lignin monomer precursors, were also found in abaca. The extractives content of the abaca fiber (0.4%) was low, and the most predominant compounds were free sterols (24% of total extract) and fatty acids (24% of total extract). Additionally, significant amounts of steroid ketones (10%), triglycerides (6%), omega-hydroxyfatty acids (6%), monoglycerides (4%), fatty alcohols (4%), and a series of p-hydroxycinnamyl (p-coumaric and ferulic acids) esterified with long chain alcohols and omega-hydroxyfatty acids were also found, together with minor amounts of steroid hydrocarbons, diglycerides, alpha-hydroxyfatty acids, sterol esters, and sterol glycosides.

Bacosterol Glycoside, a New 13,14-Seco-steroid Glycoside from Bacopa monnieri

A new sterol glycoside, bacosterol-3-O-beta-D-glucopyranoside along with bacopasaponin-C, bacopaside-I, bacopaside-II, bacosterol, bacosine and luteolin-7-O-beta-glucopyranoside have been isolated from Bacopa monnieri. Their structures were elucidated mainly on the basis of IR, 1D, 2D NMR (HMQC, HMBC, COSY), HR-ESI-QTOF-MS and EI mass spectral studies.

A new sterol glycoside from Securidaca inappendiculata

From the roots of Securidaca inappendiculata, one new sterol glycoside securisteroside (1) has been isolated, along with two known sterols, spinasterol (2) and 3-O-β-D-glucopyranosyl-spinasterol (3). The new sterol was characterized by chemical and spectrometric methods, including EIMS, FABMS and one- and two-dimensional NMR experiments.

Neutral glycolipids of the filamentous fungus Neurospora crassa:altered expression in plant defensin-resistant mutants

To defend themselves against fungal pathogens, plants produce numerous antifungal proteins and peptides, including defensins, some of which have been proposed to interact with fungal cell surface glycosphingolipid components. Although not known as a phytopathogen, the filamentous fungus Neurospora crassa possesses numerous genes similar to those required for plant pathogenesis identified in fungal pathogens (Galagan, J. E., et al. 2003. Nature 422: 859-868), and it has been used as a model for studying plant-phytopathogen interactions targeting fungal membrane components (Thevissen, K., et al. 2003. Peptides. 24: 1705-1712). For this study, neutral glycolipid components were extracted from wild-type and plant defensin-resistant mutant strains of N. crassa. The structures of purified components were elucidated by NMR spectroscopy and mass spectrometry. Neutral glycosphingolipids of both wild-type and mutant strains were characterized as beta-glucopyranosylceramides, but those of the mutants were found with structurally altered ceramides. Although the wild type expressed a preponderance of N-2'-hydroxy-(E)-Delta3-octadecenoate as the fatty-N-acyl component attached to the long-chain base (4E,8E)-9-methyl-4,8-sphingadienine, the mutant ceramides were found with mainly N-2'-hydroxyhexadecanoate instead. In addition, the mutant strains expressed highly increased levels of a sterol glucoside identified as ergosterol-beta-glucoside. The potential implications of these findings with respect to defensin resistance in the N. crassa mutants are discussed.

An acetoxygenated analogue of ergosterol from a soft coral of the genus Lobophytum

Chemical investigation of a soft coral of the genus Lobophytum of the Andaman and Nicobar coasts resulted in the isolation of a new marine sterol acetate, (24S)-ergostane-3β,5α,6β,25-tetraol-3,6,25-triacetate (1) and of two known sterol glycosides 3β,4α-dihydroxypregn-20-ene-4-O-β-D-arabinopyranoside and 24-methylenecholest-5-ene-3β,7β,16β-triol-3-O-α-L-fucopyranoside-7β-acetate. The structures of the compounds were elucidated based on spectral studies and chemical conversions.