Polysaccharides of algae 67. Carrageenan from Pacific red alga Turnerella mertensiana (Gigartinales,Rhodophyta)

A sulfated galactan composed of nearly equimolar amounts of d-galactose, 3,6-anhydro-d-galactose, and sulfate was isolated from the red alga Turnerella mertensiana collected in the Sea of Japan. The structures of native polysaccharide and its alkaline modification products were studied by NMR spectroscopy. The polysaccharide molecules were shown to contain a linear carbohydrate chain consisting of alternating 3-linked β-d-galactopyranose 4-sulfate and 4-linked 3,6-anhydro-α-d-galactopyranose residues (known as к-carrageenan), which is typical of carrageenans, but the regularity of polymer structure is masked by the presence of some 3,6-anhydro-α-d-galactose 2-sulfate (ι-carrageenan units) and α-D-galactose 6-sulfate (µ-carrageenan units) instead of 3,6-anhydro-α-d-galactose. Upon addition of potassium chloride (up to 4%) to a solution of the native polysaccharide, about half of the substance transforms into gel. The gel-forming fraction is к-ι-µ-hybrid carrageenan with the ～65 : 15 : 20 ratio of к-, ι-, and µ-units. The non-gelling fraction contains the к-, ι-, and µ-units at the ratio of ～46 : 12 : 42. The gel-forming carrageenan product free of µ-units can be otained in ～30% yield (based on the dry biomass) by alkaline treatment of the alga prior to extraction of the polysaccharide.

     

Polysaccharides of algae 68. Sulfated polysaccharides from the Kamchatka brown alga Laminaria bongardiana

Several fucoidan fractions were isolated from the biomass of the Kamchatka brown alga Laminaria bongardiana by hot water extraction followed by anion-exchange chromatography. Fucoidans were found to be composed of l-fucose, d-galactose, and sulfate as the major components, whereas d-xylose, d-mannose, d-glucuronic acid, and acetate were detected as the minor constituents. Highly sulfated fucoidan fractions F-2 and F-3 were solvolytically desulfated by heating in dimethyl sulfoxide in the presence of pyridine. The structures of native and desulfated polysaccharides were investigated by the methylation analysis and NMR spectroscopy. It was shown that F-2 contains fucan sulfate, the backbone of which is made of 1→3-linked α-l-fucopyranose residues with single α-l-Fucp branches at positions 2 and sulfate groups predominantly at positions 4. Sulfated fucoglucuronomannan, fucoglucuronan, and fucogalactan were detected in F-2 as concomitant polysaccharides. Fucan sulfate and sulfated fucogalactan were the major components of the fraction F-3. The anticoagulant properties of fucoidan fractions were assessed. It was demonstrated that the activity of the fraction F-3 is comparable with that of low-molecular-weight heparin (enoxaparin), whereas the activity of total fucoidan F and the fraction F-2 is ~2/3 and ~1/2, respectively, of the activity of F-3, which is in accordance with the lower sulfate content in these samples. Desulfated preparations F-2deS and F-3deS were completely devoid of anticoagulant activity.

     

Quantitative Analysis of Caffeoylquinic Acids and Styrylpyrones in Sweetia panamensis Bark by UPLC

Six secondary metabolites from the methanolic extract of Sweetia panamensis (Fabaceae) bark were isolated and characterised. Along with the pyrones desmethylangonine β-d-O-glucopyranoside and desmethylangonine β-d-O-glucopyranosyl-(1→6)-O-β-d-glucopyranoside, already reported in this species, 5-O-caffeoylquinic acid (chlorogenic acid), 4-O-caffeoylquinic acid, 3-O-caffeoylquinic acid and the isoflavonoid 5-O-methylgenistein 7-O-β-d-glucopyranoside were isolated for the first time from S. panamensis. Additionally, an LC-ESI-MS qualitative analysis was performed and an ultra performance liquid chromatography (UPLC) method was developed and validated for the determination of these compounds. The UPLC method was applied to the quantitative analysis of plant samples. Pyrones and caffeoylquinic acids resulted to be the main compounds in the extract; in particular desmethylangonine β-d-O-glucopyranosyl-(1→6)-O-β-d-glucopyranoside was the most abundant compound.

     

Determination of Tryptophan in Lysozyme and Lysozyme Hydrolysate by Chiral LC Using d-Tryptophan as Internal Standard

In the present study, a new LC method is described for the quantitation of tryptophan (Trp) in lysozyme and enzymatic lysozyme hydrolysate. To compensate for partial breakdown of Trp during hydrolysis with 4 M methanesulfonic acid, an enantiomer dilution method was developed. The method makes use of free d-Trp or a d-Trp-containing dipeptide as internal standard for the quantitation of l-tryptophan in these matrices. After acid hydrolysis in 4 M methanesulfonic acid, LC analysis is performed on a Crownpak CR chiral column in combination with fluorescence detection. Optimum time and temperature for the acid hydrolysis were investigated in order to obtain complete hydrolysis of the source materials. A comparison of the l-Trp recoveries was made for d-Trp and Gly-d-Trp as internal standards. By choosing a hydrolysis time of 150 min at 150 °C, 93% recovery of l-Trp from lysozyme was achieved. Under these conditions, no racemization occurred. When choosing d-Trp as internal standard, a direct LC method for l-Trp in lysozyme and enzymatic lysozyme hydrolysate was established without the need for pre-column derivatization and without the need to use Trp protecting agents during acid hydrolysis.

     

Enantioseparation of Three β-Agonists Using Di-n-butyl d-Tartrate-Boric Acid Complex as Chiral Selector by Means of MEEKC

In this study, a self-prepared complex chiral selector, di-n-butyl d-tartrate-boric acid complex, by the reaction of di-n-butyl d-tartrate with boric acid in a running buffer was used as a chiral selector for the enantioseparation of three β-agonists including clenbuterol, cycloclenbuterol and tulobuterol by means of microemulsion electrokinetic chromatography (MEEKC). Three β-agonists were successfully enantioseparated using the chiral system, indicating that the di-n-butyl d-tartrate-boric acid complex was a useful chiral selector. The effects of di-n-butyl d-tartrate and sodium tetraborate concentration, surfactant concentration, cosurfactant, phosphate, buffer pH and composition, as well as applied voltage were extensively investigated to achieve a good enantioseparation. The di-n-butyl d-tartrate and sodium tetraborate concentration in the running buffer had great influence on the chiral resolution (R _s). Three β-agonists which could not be separated with only di-n-butyl d-tartrate, obtained good chiral separation using the complex chiral selector; among them, two pairs including clenbuterol and cycloclenbuterol could be baseline resolved in 7 min under optimized experimental conditions of 0.8% (w/v) di-n-butyl d-tartrate, 40 mM sodium tetraborate, 3.0% (w/v) Tween-20 and 60 mM sodium dihydrogen phosphate with 25 kV as running voltage. The results indicated that the method could be used for the enantioseparation of three β-agonists.

     

Simultaneous Determination of Safingol and d-erythro-Sphinganine in Human Plasma by LC with Fluorescence Detection

l-threo-Sphinganine (safingol) is a putative synthetic sphingosine kinase inhibitor currently being tested in clinical trials as an anticancer agent. To enable defining the pharmacokinetic properties of safingol in humans, we developed a sensitive analytical method to simultaneously quantitate safingol and its naturally-occurring diastereomer, d-erythro-sphinganine in human plasma. Of the two different fluorogenic derivatization agents (NDA and OPA) and several pH conditions compared for the derivatization, we found that NDA derivatization achieved more than 20 times greater sensitivity compared with OPA derivatization, and pH 9.0 showed the highest sensitivity for both compounds. An analytical method for liquid chromatography (LC) with a fluorescence detector (FLD) was developed and validated with calibration curve ranges of 20–1,000 ng mL⁻¹ for safingol and d-erythro-sphinganine. Our LC-FLD method using NDA-derivatization enabled simultaneous quantification of safingol and its naturally-occurring diastereomer, d-erythro-sphinganine with satisfactory sensitivity in human plasma.

     

Quality Assessment of Veratrum nigrum L. by LC-ELSD Fingerprints and LC Quantitative Analysis

A rapid and sensitive LC-MS method has been developed for the determination of luteolin-7-O-β-d-glucoside in rat plasma after solvent extraction. Separation was on an Elite Hypersil ODS2 column (250 mm × 4.6 mm i.d., 5 μm) with a mobile phase of acetonitrile-0.3% acetic acid (26:74, v/v). The samples were analyzed by using positive electrospray ionization MS in selected ion monitoring mode. The selected ions for luteolin-7-O-β-d-glucoside and the internal standard, isoquercitrin, were m/z 448.95 and m/z 464.95. Good linearity was observed over the range of 20–2,000 ng mL⁻¹ with a lower limit of quantification of 20 ng mL⁻¹. No interference peaks or matrix effects were observed. The validated method was applied to the pharmacokinetic study of luteolin-7-O-β-d-glucoside in rat plasma after intravenous administration of Kudiezi Injection.

     

Polysaccharides of algae 65. Unusual polysaccharide composition of the pacific brown alga Punctaria plantaginea

Quantitative determination revealed the presence of storage glucan (6.0%), fucoidan (19.2%) and alginate (12.7%) in the biomass of the brown alga Punctaria plantaginea collected from the Sea of Japan. The polysaccharides were isolated from the alga by fractional extraction followed by additional purification procedures. Unlike the well-known laminarans the storage polysaccharide from P. plantaginea was shown to be a linear (1→6)-β-d-glucopyranan, which is new for brown alga. The content of guluronic acid (G) residues in the alginate molecules exceeded the content of mannuronic acid residues (M), M/G = 0.5. Poly-G and poly-MG blocks were isolated from the products of partial hydrolysis of alginic acid; however, a heterogeneous mixture of polysaccharide fragments was obtained instead of the expected poly-M fraction. Preliminary data suggests that fucoidan from this alga is a new for brown algae type of sulfated polysaccharide (xylofucan) with a main backbone built of α-l-fucopyranose residues. This chain contains multiple sulfate groups and single non-sulfated β-d-xylopyranose residues as substituents.     

Une Autre Approche A La Synthese De Derives Benzyles Des Monosaccharides Reducteurs. Etude Des Equilibres Pyrannose-Furannose Par R.M.N. Du Carbone-13

Abstract

Perbenzyl derivatives of d-glucose, d-mannose, d-galactose, d-xylose, d-ribose and l-arabinose were prepared by treatment of reducing sugars with benzyl bromide in DMSO in the presence of potassium hydroxyde and the composition (α/β, Pyranoside/Furanoside) of the reaction mixtures determined by ¹³C-Nuclear Magnetic Resonance spectroscopy. Most of the per-O-benzyl glycosides were obtained in crystalline form unlike the corresponding methyl per-O-benzyl glycosides. Benzylation of d-mannose gave almost exclusively penta-O-benzyl-β-d-mannopyranoside (≥ 95%) as cristalline material. Benzylated reducing sugars were further obtained in good yield by acid hydrolysis of above compounds.     

Fast and Precise Quantification of l-Homoarginine in Human Plasma by HILIC-Isotope Dilution-MS–MS

Lowered plasma concentrations of the endogenous amino acid l-homoarginine have been recently identified as an independent risk factor for cardiovascular and all-cause mortality in patients referred for coronary angiography in the LURIC study. To support further investigations into this matter, we describe here a fast and easy LC–MS–MS method for the detection of l-homoarginine in human plasma. The sample preparation consisted only of the addition of the stable isotope-labeled internal standard d ₄-l-homoarginine and protein precipitation. The analytes were separated isocratically on an HILIC silica column. Detection took place by tandem mass spectrometry. The calibration function was linear in the range of 0.1–10 μmol L⁻¹. The intra-day precision was better than 2 % RSD and the inter-day precision better than 4 % RSD in plasma. The accuracy was always better than 5 % deviation. The method was matrix independent owing to the usage of the analogous stable isotope-labeled internal standard.

     

Heat capacities and thermodynamic functions of d-ribose and d-mannose

The heat capacities of d-ribose and d-mannose have been studied over the temperature range from 1.9 to 440 K for the first time using a combination of Quantum Design Physical Property Measurement System and a differential scanning calorimeter. The purity, crystal phase and thermal stability of these two compounds have been characterized using HPLC, XRD and TG–DTA techniques, respectively. The heat capacities of d-Mannose have been found to be larger than those of d-ribose due to its larger molecular weight, and the solid–liquid transition due to the sample melting has also been detected in the heat capacity curve. The heat capacities of these two compounds have been fitted to a series of theoretical models and empirical equations in the entire experimental temperature region, and the corresponding thermodynamic functions have been derived based on the curve fitting in the temperature range from 0 to 440 K. Moreover, the phase transition enthalpy and melting temperature of these two compounds have also been determined from the heat flows obtained in DSC measurements.

     

ASCOPYRONE P: CHEMICAL SYNTHESIS FROM d-GLUCOSE

The pyranone, 1,5-anhydro-4-deoxy-d-glycero-hex-1-en-3-ulose (1) (ascopyrone P), has been synthesised in eight steps from d-glucose. The key steps were deacetylation of 3,6-di-O-acetyl-1,5-anhydro-d-glycero-hex-3-en-2-ulose (8) to give isomers and hydrates of 1,5-anhydro-4-deoxy-d-glycero-hex-3-en-2-ulose (9). Isomerisation of this mixture afforded 1,5-anhydro-4-deoxy-d-glycero-hex-1-en-3-ulose (1) (ascopyrone P) in a moderate yield.     

Structural Elucidation of an Elicitor-Active Oligosaccharide,LN-3, Prepared from Algal Laminaran

Abstract

The primary structure of an elicitor-active oligosaccharide, LN-3, prepared from partially hydrolyzed algal laminaran was determined by means of the analyses of glycosyl-linkage, fragments by acetolysis, and glycosyl-sequence. The elicitor-active oligosaccharide, LN-3, is a pyridylaminated hepta-β-d-glucoside which was shown to have the following linear structure: β-d-Glcp(1→6)-β-d-Glcp(1→3)-β-d-Glcp(1→3)-β-d-Glcp(1→3)-β-d-Glcp(1→6)-β-d-Glcp(1→3)-Glc-PA.     

Synthesis of Methyl α-d-Allopyranoside and Methyl α-d-Ribo-hexopyranoside: A Convenient Chemoenzymatic Approach

Abstract

An efficient chemoenzymatic synthesis of methyl α-d-allopyranoside and methyl 3-deoxy-α-d-ribo-hexopyranoside starting from methyl 4,6-O-benzylidene-α-d-glucopyranoside is described.     

Synthesis of Non-glucosamino Glucan Oligosaccharides Related to Heparin and Heparan Sulphate

Abstract

A series of three oligosaccharides, α-d-Glc-(1→4)-β-d-GlcA-1ωe, β-d-GlcA-(1→4)-α-d-Glc-(1→4)-β-d-GlcA-lωe and α-d-Glc-(1→4)-β-d-GlcA-(1→4)-α-d-Glc-(1→4)-β-d-GlcA-1ωe was prepared by a short synthetic route, using maltose and glucuronic acid derivatives as starting materials. The oligosaccharides contain glucose residues instead of glucosamines, and have a less complicated structure than the corresponding unsulphated structures found in native heparin and heparan sulphate. This simplification in structure has diminished the number of synthetic steps and raised the total yield compared to the preparation of the corresponding heparin/heparan sulphate structures which have been found to bind acidic and basic FGF.     

A Convenient Synthesis of Pyranosyl-1-carbaldoximes

Abstract

A simple high-yielding procedure is described for the preparation of tri-O-acetyl-β-l-fucopyranosylformaldoxime (1) involving stannate(II)-mediated reduction of the readily accessible tri-O-acetyl-β-l-fucopyranosylnitromethane (3). The d-mannosyl, d-glucosyl, d-galactosyl, and d-xylosyl analogues 7–12 were prepared similarly. The structure of tetra-O-acetyl-β-d-mannopyranosylformaldoxime (7) was determined by X-ray crystallography.     

The Development and Validation of a Stability-Indicating UHPLC-DAD Method for Determination of Perindopril l-Arginine in Bulk Substance and Pharmaceutical Dosage Form

A stability-indicating ultra-high-performance liquid chromatography (UHPLC) method with a diode array detector was developed and validated for the determination of cis/trans isomers of perindopril l-arginine in bulk substance and pharmaceutical dosage form. The separation was achieved on a Poroshell 120 Hilic (4.6 × 150 mm, 2.7 µm) column using a mobile phase composed of acetonitrile–0.1 % formic acid (20:80 v/v) at a flow rate of 1 mL min⁻¹. The injection volume was 5.0 µL and the wavelength of detection was controlled at 230 nm. The selectivity of the UHPLC-DAD method was confirmed by determining perindopril l-arginine in the presence of degradation products formed during acid–base hydrolysis and oxidation as well as degradation in the solid state, at an increased relative air humidity and in dry air. The method’s linearity was investigated in the ranges 0.40–1.40 µg mL⁻¹ for isomer I and 0.40–2.40 µg mL⁻¹ for isomer II of perindopril l-arginine. The UHPLC-DAD method met the precision and accuracy criteria for the determination of the isomers of perindopril l-arginine. The limits of detection and quantitation were 0.1503 and 0.4555 µg mL⁻¹ for isomer I and 0.0356 and 0.1078 µg mL⁻¹ for isomer II, respectively.

     

Stereoselective Glycosidic Coupling Reactions of Fully Benzylated 1,2-Anhydro Sugars with N-Tosyl- or N-Benzyloxycarbonyl-l-serine Methyl Ester

Abstract

The glycosidic coupling reaction of 1,2-anhydro-3,4,6-tri-O-benzyl-β-d-mannopyranose (7), 1,2-anhydro-3,4,6-tri-O-benzyl-α-d-galactopyranose (21), and 1,2-anhydro-3,4-di-O-benzyl-α-d-xylopyranose (18) with N-tosyl- (10) or N-benzyloxycarbonyl- (11) L-serine methyl ester provides a new stereocontrolled synthesis of 1,2-trans linked glycopeptides. The 1,2-anhydro sugars are shown to react smoothyl with 10 or 11 in the presence of Lewis acid (ZnCl₂ or AgOTf) as well as powdered 4A molecular sieves in CH₂Cl₂ at room temperature to afford glycosyl serine derivatives with high stereoselectivity and high yield in less than 30 min. An improved method using 2-O-acetyl-3,4,6-tri-O-benzyl-α-d-mannopyranosyl chloride (6) as the key intermediate for ring closure was applied for the synthesis of 1,2-anhydro-3,4,6-tri-O-benzyl-β-d-mannopyranose.     

Thermal decomposition of algae bloom biomass

The algae bloom biomass in the water reservoir ‘Rybnik’ is an important problem, and not only in Poland [1,2]. The algae growth in the water affects its odour, colour, taste and quality [3]. Algae bloom biomass removed from water can be treated in the following ways:

disposal in sanitary landfills

storage on special dumping grounds

fermentation

dewatering and incineration

In this paper the physicochemical composition and thermal analysis of the biomass of algae bloom dried at 378 K or in the open air are described. Thermal analytical measurements were made in an air atmosphere.     

Two new triterpenoids from Nauclea officinalis

Two new triterpenoids and three 27-nor-triterpenoids were isolated from the stems (with bark) of Nauclea officinalis. Their structures were identified to be 2β,3β,19α,23-tetrahydroxy-urs-12-en-28-oic acid (1), 2β,3β,19α,23-tetrahydroxy-urs-12-en-28-O-[β-d-glucopyranosyl (1-2)-β-d-glucopyranosyl] ester (2), pyrocincholic acid 3β-O-α-l-rhamnopyranoside (3), pyrocincholic acid 3β-O-α-l-rhamnopyranosy1-28-O-β-d-glucopyranosyl ester (4), pyrocincholic acid 3β-O-α-l-rhamnopyranosy1-28-O-β-d-glucopyranosyl-(1-6)-β-d-glucopyranosyl ester (5) by spectroscopic methods including 1D, 2D NMR and HR-MS analyses. The cytotoxic activity of 1–5 against lung cancer A-549 cells was also investigated.