Changes in the lipid composition of embryonic cells of the mussel Mytilus trossulus during cryopreservation

A comparative analysis of the lipid composition of embryonic cells of the mussel Mytilus trossulus prior to, and after, cryopreservation in liquid nitrogen was carried out in the presence of two types of cryoprotectors: 1) dimethylsulfoxide and trehalose; and 2) dimethylsulfoxide, trehalose, total lipid extract from the mussel Crenomytilus grayanus, alpha-tocopherol and ascorbic acid. It was found that not only the cell viability but also the fatty acid composition of cell lipids after cryopreservation depend on the composition of cryoprotectors used. The content of saturated fatty acids, monoenic and polyenic fatty acids, the omega 3/omega 6 ratio, and the index of nonsaturation in the fatty acid composition of lipids was shown to change remarkably after cryopreservation. Possible reasons of these changes are discussed.     

Main phospholipids and their fatty acid composition in muscle and cephalothorax of the edible Mediterranean crustacean Palinurus vulgaris (spiny lobster)

The total lipids of muscle and cephalothorax of Mediterranean lobster Palinurus vulgaris were found to be 1.0% and 2.4% of the wet tissue of which the phospholipids represented 66.5% and 47.5%, respectively. The main PhL saturated, monounsaturated and polyunsaturated fatty acids in muscle and cephalothorax were C16:0, C18:0, C18:1ω-9, C18:1ω-7, C20:4ω-6, C20:5ω-3 and C22:6ω-3. 2-OH C14:0 and cyclo-17:0 fatty acids were also identified though in low percentages. The main individual PhL in muscle were found to be phosphatidylcholine (53.5%), 72.0% of which corresponded to the structure of 1,2-diacyl-glycerocholine while the rest 28.0% to 1-O-alkyl-2-acyl-glycerocholine or 1-O-(1-alkenyl)-2-acyl-glycerocholine and phosphatidylethanolamine (19.3%), 75.0% of which corresponded to the structure of 1,2-diacyl-glyceroethanolamine and 25% to 1-O-alkyl-2-acyl-glyceroethanolamine or 1-O-(1-alkenyl)-2-acyl-glyceroethanolamine. Cephalothorax main PhL were found to be PC and PE (66.4% and 18.8%, respectively). In muscle and cephalothorax PC ω-3 fatty acids amounted 7.78% and 8.60%, while in PE amounted 30.77% and 23.65% respectively. Furthermore, in both tissues PhL, cardiolipine phosphatidylserine, phosphatidylinositol, sphingomyelin and lysophosphatidylcholine, were also found.     

Polyphthienoyl trehalose, glycolipids specific for virulent strains of the tubercle bacillus

Phthienoic acids constitute a family of dextro-rotary odd-numbered unsaturated fatty acids isolated exclusively from virulent strains of human and bovine tubercle bacilli. In the bacterial cell they are not free and a search for their linked form in complex wall lipids of Mycobacterium tuberculosis (strain Canetti) showed that they esterified trehalose. Structural elucidation of the major phthienoyl trehalose showed the occurrence of five acyl residues located at 2, 2', 3', 4 and 6' positions of trehalose. The acyl substituents were mainly 2,4,6-trimethyl tetracos-2-enoic acid (C27 phthienoic acid) accompanied by its homologs. In addition to these branched fatty acids, straight-chain C16 and C18 acyls composed about 20% of the substituents. The proposed structure is a new one, both for the mycobacterial-specific glycolipid and for the substituted positions on trehalose. Other minor acyl trehaloses were detected in M. tuberculosis (strain Canetti), differing from the major component by the occurrence of an additional hydroxy fatty acid (3-hydroxy-2,4,6-trimethyl tetracosanoic acid) or by the number of acyl substituents. The major glycolipid presented a weak activity in vitro on mitochondrial oxidative phosphorylation. These glycolipids and phthienoic acids could serve as virulence indicators.     

Saponins from Albizzia lucida.

Three main saponins were isolated from the seeds of Albizzia lucida. Their structures were established by spectral analyses and chemical and enzymatic transformations as 3-O-[β- -xylopyranosyl(1→2)-- -arabinopyranosyl (1→6)] [β- -glucopyranosyl (1→2)] β- -glucopyranosyl echinocystic acid; 3-O-[- -arabinopyranosyl (1→6)][β- -glucopyranosyl (1→2)]-β- -glucopyranosyl echinocystic acid and 3-O-[β- -xylopyranosyl (1→2)-β- -fucopyranosyl (1→6)-2-acetamido-2-deoxy-β- -glucopyranosyl echinocystic acid, characterized as its methyl ester.     

Some ring-opening reactions of a diepoxide derived from (−)-quinic acid

A useful preparative route to nitrogen-containing, carbocyclic derivatives is described from (−)-quinic acid. (−)-Quinic acid was converted via the 3,4-O-cyclohexylidene-lactone into 1- -3-O-tosyl-5-C-tosyloxymethylcyclohexane-1,2,5/3-tetrol (5) by sequential reduction with sodium borohydride, toluene-p-sulphonylation, and acid hydrolysis. Reaction of the disulphonate 5 with methanolic sodium methoxide afforded 1- -1,2:5,7-dianhydro-5-C-hydroxymethylcyclohexane-1,2,3,5/0-tetrol (6). The ring-opening reactions of the diepoxide 6 with azide ion furnished a mixture of two diazides 9 and 13 in the ratio 4 to 1. The structure and conformation of the derived dibenzoates 10 and 14 have been determined by n.m.r. spectroscopy.     

A study of the role of the hexose monophosphate pathway with respect to fatty acid biosynthesis in sporulation of Saccharomyces cerevisiae

13C NMR was used to study the pattern of label incorporation from [2-13C]acetate into trehalose during sporulation in Saccharomyces cerevisiae. A wild-type strain and a strain homozygous for the zwf1 mutation (which affects glucose-6-phosphate dehydrogenase) were used. In the wild-type it was possible to deduce the cycling of glucose 6-phosphate around the hexose monophosphate pathway whilst in the mutant strain this did not occur. The requirement of the hexose monophosphate pathway for providing NADPH for fatty acid biosynthesis was examined using 13C NMR and GC/MS. The wild-type strain produced a typical profile of fatty acids with palmitoleic acid being the most abundant whereas the mutant contained only one-quarter the amount of total fatty acid. As zwf1 homozygous diploids are able to sporulate this indicates that the large amount of fatty acid biosynthesis observed in sporulation of wild-type strains is not essential to the process.     

石蜡酪杆菌B126产生的糖脂的理化性质

通过纸层析、硅胶薄层层析和气相色谱分析表明,石蜡酪杆菌(Caseobacter paraffinicum)B126至少产生两种糖脂,其主要产物是海藻糖脂。它由海藻糖和两种以上的脂肪酸(十六碳酸和十八碳酸)所组成。其表面张力和界面张力(对重液体石蜡)分别为28～29和1～2mN/m,临界胶束浓度(CMC)较低,为64mg/L。     

Alterations in fatty acid composition and trehalose concentration ofSaccharomyces brewing strains in response to heat and ethanol shock

Summary The effects of heat and ethanol shock on fatty acid composition and intracellular trehalose concentration of lager and ale brewing yeasts were examined. Exposure of cells to heat shock at 37°C or 10% (v/v) ethanol for 60 min resulted in a significant increase in the ratio of the total unsaturated to saturated fatty acyl residues and the intracellular trehalose concentration of cells. A similar increase in the amount of unsaturated fatty acids was observed in cells after 24 h of fermentation of 16°P (degree Plato) or 25°P wort, at which time more than 2% (v/v) ethanol was present in the growth medium. These results suggest that unsaturated fatty acids and high concentrations of intracellular trehalose may protect the cells from the inhibitory effects of heat and ethanol shock.     

Chemical structure of kenaf xylan

Methylation and partial acid hydrolysis of xylans from the bast and core of kenaf (Hibiscus cannabinus) showed that the main chain of these xylans consists of (1 → 4)-linked β-d-xylopyranosyl (Xylp) residues, some of which carry a -1,2-linked 4-O-methyl-glucopyranosyluronic acid (Me-GlcAp) and glucopyranosyluronic acid (GlcAp) residues as side chains. Partial hydrolysis of kenaf xylans afforded two series of aldouronic acids from aldobio- to aldotetraouronic acids. The acids of the first series composed of 4-O-Me-d-GlcAp and d-Xylp residues: 4-O-Me-GlcA-Xyl₃, 4-O-Me-GlcA-Xyl₂ and 4-O-Me-GlcA-Xyl. The second series composed of d-GlcAp and d-Xylp: GlcA-Xyl₃, GlcA-Xyl₂ and GlcA-Xyl.

In addition to these acids, another aldobiouronic acid, 4-O-(-d-GalAp)-d-Xyl was found to be present in the partial hydrolysate.

The molar ratio of GalA, GlcA, 4-O-Me-GlcA, and Xyl residues was calculated to be 1.0:2.0:9.4:119 for the bast xylan and 1.0:1.3:7.9:99.4 for the core xylan.     

Acylated flavonol diglucosides from Lotus polyphyllos

Three acylated flavonol diglucosides, kaempferol 3-O-β-(6″-O-E-p-coumaroylglucoside)-7-O-β-glucoside; quercetin 3-O-β-(6″-O-E-p-coumaroylglucoside)-7-O-β-glucoside; isorhamnetin 3-O-β-(6″-O-E-p-coumaroylglucoside)-7-O-β-glucoside were isolated from the whole plant aqueous alcohol extract of Lotus polyphyllos. The known 3,7-di-O-glucosides of the aglycones kaempferol, quercetin and isorhamnetin were also characterized. All structures were established on the basis of chemical and spectral evidence.     

Cycloartane triterpene glycosides from Astragalus trigonus

Three new cycloartane glycosides, trigonoside I, II and III, and the known astragalosides I and II were isolated from the roots of Astragalus trigonus. The structures of the new glycosides were totally elucidated by high field (600 MHz) NMR analyses as cycloastragenol-6-O-β-xylopyranoside, cycloastragenol-3-O-[-l-arabinopyranosyl(1 → 2)-β-d-xylopyranosyl]-6-O-β- d-xylopyranoside and cycloastragenol-3-O-[-l-arabinopyranosyl(1 → 2)-β-d-(3-O-acetyl)-xylopyranosyl]-6-O-β-d-xylopyranoside.     

Iridoid glucosides from Thunbergia laurifolia

Two iridoid glucosides, 8-epi-grandifloric acid and 3′-O-β-glucopyranosyl-stilbericoside, were isolated from the aerial part of Thunbergia laurifolia along with seven known compounds, benzyl β-glucopyranoside, benzyl β-(2′-O-β-glucopyranosyl) glucopyranoside, grandifloric acid, (E)-2-hexenyl β-glucopyranoside, hexanol β-glucopyranoside, 6-C-glucopyranosylapigenin and 6,8-di-C-glucopyranosylapigenin. Strucural elucidation was based on the analyses of spectroscopic data.     

An acetophenone and three naphthalides from turkish Rhamnus libanoticus

A new acetophenone glycoside and two new naphthalide glycosides have been isolated from the bark of Turkish Rhamnus libanoticus together with 7-hydroxy-5-methoxyphthalide 7-O-β-D-glucoside. The structures of the new compounds were elucidated by spectroscopic methods as 2,6-dihydroxy-4-methoxyacetophenone 2-O-β- rutinoside, 8,9-dihydroxy-6-methoxynaphthalide 8-O-β-rutinoside, 8,9-dihydroxy-6-methoxynaphthalide 8-O-/3b-D glucoside, respectively.     

Synthesis of 2,3-O-(propane-1,2-diyl)- and 2,3-O-(3-hydroxypropane-1,2-diyl)-cyclomaltoheptaose

2¹,3¹-O-(Propane-1,2-diyl)cyclomaltoheptaose has been prepared from 2-O-allylcyclomaltoheptaose by mercuration in trifluoroacetic acid, followed by reduction with sodium borohydride. 2-O-(2,3-Epoxypropyl)cyclomaltoheptaose, prepared from 2-O-allylcyclomaltoheptaose by oxidation with dimethyldioxirane, was converted into 2¹,3¹-O-(3-hydroxypropane-1,2-diyl)cyclomaltoheptaose by treatment with trifluoroacetic acid. Both derivatives containing fused 1,4-dioxane rings are mixtures of stereoisomers, in which the methyl and hydroxymethyl group, respectively, that is linked to this ring, occupies an axial or an equatorial position.     

Novel pigments and copigmentation in the blue marguerite daisy

The blue colour of the petals of the blue marguerite daisy, Felicia amelloides, has been found to arise from copigmentation between a novel malonylated delphinidin triglycoside, delphinidin 3-O-neohesperidoside 7-O- (6-O-malonyl-glucoside), and a new flavone C-glycoside, swertisin 2″-O-rhamnoside-4′-O-glucoside. Recombination, in vitro, of these two petal components at pH 6 recreates the blue petal colour.     

Structure of the serine-containing capsular poly-saccharide K40 antigen from Escherichia coli O8:K40:H9

The structure of the K40 antigenic capsular polysaccharide (K40 antigen) of E. coli O8:K40:H9 was elucidated by determination of the composition, ¹H- and ¹³C-n.m.r. spectroscopy, periodate oxidation and Smith degradation, and methylation analysis. The K40 polysaccharide consists of [(O-β- -glucopyranosyluronic acid)-(1→4)-O-(2-acetamido-2-deoxy-- -glucopyranosyl)-(1→6)-O-(2-acetamido-2-deoxy-- -glucopyranosyl)-(1→4)] repeating units. All of the glucuronic acid residues are substituted amidically with -serine.     

Determination of 2-hydroxypropyl-γ-cyclodextrin in plasma of cynomolgus monkeys after oral administration by gas chromatography–mass spectrometry

This report describes a specific and highly sensitive gas chromatography–mass spectrometry (GC–MS) assay for the analysis of industrially produced 2-hydroxypropyl-γ-cyclodextrin, a heterogeneous mixture of homologues and isomers, in plasma of cynomolgus monkeys. Instead of analyzing the polysaccharide mixture as a whole, in a first step the HP-γ-cyclodextrin mixture, together with the internal standard (2,6-di-O-methyl-β-cyclodextrin), was deuteromethylated, and in a second step hydrolyzed with hydrochloric acid to the respective monosaccharides. The resulting reaction mixture was trimethylsilylated to 1,4-bis(O-trimethylsilyl)-2,3-bis-O-deuteromethyl-6-O-2′-deuteromethoxypropylglucose (representative for HP-γ-CD) and 1,4-bis-(O-trimethylsilyl)-bis-2,6-O-methyl-3-O-deuteromethylglucose (representative for the internal standard), respectively, and analyzed by GC–MS. The limit of quantification of this assay was 20 nmol/l.     

Regioselective acylation of several polyhydroxylated natural compounds by Candida antarctica lipase B

Regioselective acylation of four polyhydroxylated natural compounds, deacetyl asperulosidic acid (1), asperulosidic acid (2), puerarin (3) and resveratrol (4) by Candida antarctica Lipase B in the presence of various acyl donors (vinyl acetate, vinyl decanoate or vinyl cinnamoate) was studied. Compounds 1, 2 and 4 were regioselectively acetylated with vinyl acetate to afford products, 3'-O-acetyl-10-O-deacetylasperulosidic acid (1a), 3',6'-O-diacetyl-10-O-deacetylasperulosidic acid (1b), 3'-O-acetylasperulosidic acid (2a), 3',6'-O-diacetylasperulosidic acid (2b), 4'-O-acetylresveratrol (4a), respectively, with yields of 22 to 50%, while reactions with vinyl decanoate and vinyl cinnamoate were slow with lower yields. Compound 3 was readily acylated with all three acyl donors and quantitatively converted to products 6'-O-acetylpuerarin (3a), 6'-O-decanoylpuerarin (3b), 6'-O-cinnamoylpuerarin (3c), respectively. The structures of these acylated products were determined by spectroscopic methods (MS and NMR).