New 4-O-substituted xylosyl units in the xyloglucan from leaves of Hymenaea courbaril

A homogeneous fucogalactoxyloglucan, isolated from the leaves of Hymenaea courbaril, was analysed by methylation-GC–MS. These procedures involved derived partially O-methylated alditol acetates and acetylated aldononitriles, which demonstrated the presence of both 2-O- and 4-O-substituted Xylp units in the side-chains. The presence of the unusual, latter structure was confirmed by 2D NMR spectroscopy with a correlated HMQC C-4/H-4 signal at δ 77.8/3.73. A similar 4-O-substituted xylosyl structure was present in a decasaccharide Glc₄Xyl₃Gal₂Fuc obtained via endo-glucanase treatment of the polysaccharide, which gave rise to a molecular ion with m/z 1555 (ESI-MS, Na⁺ form).     

Structural features of the hemicellulose a from the stem of Mimosa bracatinga

The hemicellulose A from the stem of Mimosa bracatinga contains residues of d-xylose and 4-O-methyl-d-glucuronic acid. Smith-degradation and methylation data indicate it to consist of a backbone of (1 → 4)-linked β-d-xylopyranosyl residues with side chains consisting of single units of 4-O-methyl--d-glucosyluronic acid attached to position 3. The branched structure was also indicated by Smith-degradation and methylation analysis of the oligosaccharides obtained by enzymic hydrolysis of the hemicellulose.     

Six new C21 steroidal glycosides from Asclepias curassavica L

Six new C₂₁ steroidal glycosides, named curassavosides A–F (3–8), were obtained from the aerial parts of Asclepias curassavica (Asclepiadaceae), along with two known oxypregnanes, 12-O-benzoyldeacylmetaplexigenin (1) and 12-O-benzoylsarcostin (2). By spectroscopic methods, the structures of the six new compounds were determined as 12-O-benzoyldeacylmetaplexigenin 3-O-β-d-oleandropyranosyl-(1 → 4)-β-d-digitoxopyranoside (3), 12-O-benzoylsarcostin 3-O-β-d-oleandropyranosyl-(1 → 4)-β-d-digitoxopyranoside (4), sarcostin 3-O-β-d-oleandropyranosyl-(1 → 4)-β-d-canaropyranosyl-(1 → 4)-β-d-oleandropyranosyl-(1 → 4)-β-d-digitoxopyranoside (5), sarcostin 3-O-β-d-oleandropyranosyl-(1 → 4)-β-d-canaropyranosyl-(1 → 4)-β-d-canaropyranosyl-(1 → 4)-β-d-digitoxopyranoside (6), 12-O-benzoyldeacylmetaplexigenin 3-O-β-d-glucopyranosyl-(1 → 4)-β-d-oleandropyranosyl-(1 → 4)-β-d-canaropyranosyl-(1 → 4)-β-d-oleandropyranosyl-(1 → 4)-β-d-digitoxopyranoside (7), and 12-O-benzoylsarcostin 3-O-β-d-glucopyranosyl-(1 → 4)-β-d-oleandropyranosyl-(1 → 4)-β-d-canaropyranosyl-(1 → 4)-β-d-oleandropyranosyl-(1 → 4)-β-d-digitoxopyranoside (8), respectively. All compounds (1–8) were tested for in vitro cytotoxicity; only compound 3 showed weak inhibitory activity against Raji and AGZY cell lines.     

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.     

Polysaccharides from the seeds of Senna multijuga

The seeds of Senna multijuga were extracted with water or 1% acetic acid and treated with ethanol, resulting in two insoluble fractions. After purification, the major one (FIA, 23%) was shown to be a galactomannan (Man:Gal 2.3:1;[] = + 54.6;[η]=1340mlg⁻¹). It consists of a main chain of (1 → 4)-linked β-d-mannopyranosyl residues substituted at 06 by single-unit -d-galactopyranosyl side chains. The second fraction (FIB, 2.5%) was an O-acetyl-glucuronoarabinoxylan from the seed coats (O-acetyl 8.3 mol%; glucuronic acid 11.7%, Xyl:Ara ratio 20:1), which showed a predominance of 4-O-substituted Xylp units (84.4%), branched at 03 with non-reducing end units of Xylp, Araf and glucuronic acid. The O-acetyl positions in d-xylosyl units are at 02 (4.8%), 03 (4.4%) and 02,3 (0.9%). The ratio between 03 and 02 determined by ¹³C-nuclear magnetic resonance spectroscopy is 1.5:1.     

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.     

Effect of temperature and pH on 31P nuclear magnetic resonances of phospholipids in cholate micelles

Accurate and precise determination of phospholipid composition by ³¹P NMR spectroscopy requires correct assignments and adequate spectral resolution. Because temperature and pH may affect chemical shifts (δ), our first aim was to establish the temperature coefficient (Δδ/ΔT) of common phospholipid classes when using sodium cholate as detergent. This parameter can then be used to aid in resonance assignments. The second goal was to investigate the pH dependence of δ so that, in addition to temperature, pH control can be used to minimize spectral overlap. For phosphatidylcholine, sphingomyelin, dihydrosphingomyelin and phosphatidylglycerol, δ values were invariant with pH and temperature. Whereas the Δδ/ΔT for phosphatidylinositol was 4 × 10⁻³ ppm/°C, regardless of pH, these coefficients were highly pH-dependent for phosphatidic acid, phosphatidylethanolamine and phosphatidylserine, exhibiting maximal variations with the deprotonation of the headgroup, particularly for phosphatidic acid. These trends indicate the importance of H-bonding on δ and Δδ/ΔT for phospholipid resonances.     

Biotransformation of paeonol by Panax ginseng root and cell cultures

Panax ginseng root and cell cultures were shown to biotransform paeonol (1) into its 2-O-β-d-glucopyranoside (2). P. ginseng root cultures were also able to biotransform paeonol (1) into its 2-O-β-d-xylopyranoside (3), 2-O-β-d-glucopyranosyl(1 → 6)-β-d-glucopyranoside (4) and 2-O-β-d-xylopyranosyl(1 → 6)-β-d-glucopyranoside (5), and its demethylated derivate, 2′,4′-dihydroxyacetophenone (6). Compounds 3 and 4 are new glycosides. It is the first example that the administrated compound was converted into its xylopyranoside by plant biotransformation.     

In vitro antiplasmodial activity of extract and constituents from Esenbeckia febrifuga, a plant traditionally used to treat malaria in the Brazilian Amazon

Esenbeckia febrifuga (Rutaceae) is a plant traditionally used to treat malaria in the Brazilian Amazon region. Ethanol extract of stems displayed a good antiplasmodial activity against Plasmodium falciparum strains W-2 (IC₅₀ 15.5±0.71 μg/ml) and 3 D7 (IC₅₀ 21.0±1.4 μg/ml). Two coumarins (bergaptene 1 and isopimpinellin 2), five alkaloids (flindersiamine 3, kokusaginine 4, skimmiamine 5, γ-fagarine 6 and 1-hydroxy-3-methoxy-N-methylacridone, 7), besides a limonoid (rutaevine 8), have been isolated for the first time from this species. Antiplasmodial activity of compounds 3, 5–8 has been evaluated in vitro against P. falciparum strains (W-2 and 3D7) and the furoquinolines 5 and 6 were the most potent displaying IC₅₀ values <50 μg/ml; flindersiamine (3) showed a weak activity while alkaloid 7 and rutaevine (8) were inactive (IC₅₀>100 μg/ml).     

A new floating sensor array to detect electric near fields of beating heart preparations

A new flexible sensor for in vitro experiments was developed to measure the surface potential, Φ, and its gradient, E (electric near field), at given sites of the heart. During depolarisation, E describes a vector loop from which direction and magnitude of local conduction velocity θ can be computed. Four recording silver electrodes (14 μm × 14 μm) separated by 50 μm, conducting leads, and solderable pads were patterned on a 50 μm thick polyimide film. The conductive structures, except the electrodes, were isolated with polyimide, and electrodes were chlorided. Spacer pillars mounted on the tip fulfil two functions: they keep the electrodes 70 μm from the tissue allowing non-contact recording of Φ and prevent lateral slipping. The low mass (9.1 mg) and flexibility (6.33 N/m) of the sensor let it easily follow the movement of the beating heart without notable displacement. We examined the electrodes on criteria like rms-noise of Φ, signal-to-noise ratio of Φ and E, maximum peak-slope recording dΦ/dt, and deviation of local activation time (LAT) from a common signal and obtained values of 24–28 μV, 46 and 41 dB, 497–561 V/s and no differences, respectively. With appropriate data acquisition (sampling rate 100 kHz, 24-bit), we were able to record Φ and to monitor E and θ on-line from beat-to-beat even at heart rates of 600 beats/min. Moreover, this technique can discriminate between uncoupled cardiac activations (as occur in fibrotic tissue) separated by less than 1 mm and 1 ms.     

Anti-diabetic properties of the Canadian lowbush blueberry Vaccinium angustifolium Ait.

Incidence of type II diabetes is rapidly increasing worldwide. In order to identify complementary or alternative approaches to existing medications, we studied anti-diabetic properties of Vaccinium angustifolium Ait., a natural health product recommended for diabetes treatment in Canada. Ethanol extracts of root, stem, leaf, and fruit were tested at 12.5 μg/ml for anti-diabetic activity in peripheral tissues and pancreatic β cells using a variety of cell-based bioassays. Specifically, we assessed: (1) deoxyglucose uptake in differentiated C2C12 muscle cells and 3T3-L1 adipocytes; (2) glucose-stimulated insulin secretion (GSIS) in β TC-tet pancreatic β cells; (3) β cell proliferation in β TC-tet cells; (4) lipid accumulation in differentiating 3T3-L1 cells; (5) protection against glucose toxicity in PC12 cells. Root, stem, and leaf extracts significantly enhanced glucose transport in C2C12 cells by 15–25% in presence and absence of insulin after 20 h of incubation; no enhancement resulted from a 1 h exposure. In 3T3 cells, only the root and stem extracts enhanced uptake, and this effect was greater after 1 h than after 20 h; uptake was increased by up to 75% in absence of insulin. GSIS was potentiated by a small amount in growth-arrested β TC-tet cells incubated overnight with leaf or stem extract. However, fruit extracts were found to increase ³H-thymidine incorporation in replicating β TC-tet cells by 2.8-fold. Lipid accumulation in differentiating 3T3-L1 cells was accelerated by root, stem, and leaf extracts by as much as 6.5-fold by the end of a 6-day period. Stem, leaf, and fruit extracts reduced apoptosis by 20–33% in PC12 cells exposed to elevated glucose for 96 h. These results demonstrate that V. angustifolium contains active principles with insulin-like and glitazone-like properties, while conferring protection against glucose toxicity. Enhancement of proliferation in β cells may represent another potential anti-diabetic property. Extracts of the Canadian blueberry thus show promise for use as a complementary anti-diabetic therapy.     

Chiral macrocyclic compounds from lactose derivatives

The reaction of benzyl 2,6,6′-tri-O-benzyl-3′,4′-O-isopropylidene-β-lactoside with 1,11-ditosyloxy-3,6,9-trioxaundecane gave benzyl 2,6,6′-tri-O-benzyl-3′,4′-O-isopropylidene-3,2′-O--(3,6,9-trioxaundecane-1,11-diyl)-β-lactoside (2, 47%). Acid hydrolysis of 2 and condensation of the product with 1,14-ditosyloxy-3,6,9,12-tetra-oxatetradecane afforded benzyl 2,6,6′-tri-O-benzyl-3′,4′-O-(3,6,9,12-tetraoxa-tetradecane-1,14-diyl)-3,2′-O-(3,6,9-trioxaundecane-1,11-diyl)-β-lactoside (29%). Similarly, the reaction of benzyl 2,6,2′,4′,6′-penta-O-benzyl-β-lactoside with Ts[OCH₂CH₂]₄OTs gave benzyl 2,6,2′,4′,6′-penta-O-benzyl-3,3′-O-(3,6,9-trioxaundecane-1,11-diyl)-β-lactoside (78%). ¹H-N.m.r. spectroscopy has been used to study the formation of host-guest complexes with some of these macrocyclic compounds and benzyl ammonium thiocyanate.     

Structural heterogeneity in waxy-rice starch

Alpha-amylase of B. amyloliquefaciens was used for the structural characterization of the amylopectin from waxy-rice starch. Fractions of -dextrins with a degree of polymerization (d.p.) <5000 were isolated from amylopectin hydrolysates after 1 and 3 h. φ,β-Limit dextrins were prepared by successive phosphorolysis and beta-amylolysis of the fractions and these were analysed by a second alpha-amylolysis. Based on the hydrolysis pattern, the limit dextrins were divided into two major groups, A and B, which possessed units of clusters of d.p. 100–200 and 90–130, respectively. An extensive alpha-amylolysis resulted in characteristic distributions of dextrins with d.p. <80 which represented branched building blocks. Type A dextrins possessed more larger building blocks with d.p. 40, but less intermediate and small blocks, than type B. The φ,β-limit dextrin of the original amylopectin had a distinct distribution enriched in small building blocks. A model is proposed in which the two types of dextrins originate from regular and less regular structural domains of the amylopectin fraction within the starch granules.     

Ergosterol peroxides as phospholipase A2 inhibitors from the fungus Lactarius hatsudake

Four ergosterol derivatives (1–4) have been isolated for the first time from the fruiting bodies of a basidiomycete fungus, Lactarius hatsudake, through activity-guided fractionation. Their structures were determined, using spectroscopic analysis, as: (22E,24R)-ergosta-5,7,22-dien-3β-ol (ergosterol, 1); 5,8-epidioxy-(22E,24R)-ergosta-6,22-dien-3β-ol (ergosterol peroxide, 2); 5,8-epidioxy-(24S)-ergosta-6-en-3β-ol (3); and (22E,24R)-ergosta-7,22-dien-3β,5,6β-triol (cerevisterol, 4). Compounds 2 and 3 showed selective inhibitory activity against Crotalus adamenteus venom phospholipase A₂ (PLA₂) enzyme, but not against Apis mellifcra bee venom PLA₂. The antiphospholipase A₂ activity of compounds 2 and 3 are reported here for the first time.     

Preparation and anticoagulant activity of a low-molecular-weight sulfated chitosan

Synthesis of chitosan sulfates with low molecular weight (M_v 9000–35,000 Da) was carried out by sulfation of low molecular weight chitosan (M_v 10,000–50,000 Da). The oleum was used as sulfating agent and dimethylfornamide as medium. The chitosans were prepared by enzymatic and acidic hydrolysis of initial high molecular weight chitosan as well as by extrusion solid-state deacetylation of chitin. As was shown by FT-IR and NMR-methods and elemental analysis, the sulfation occurred at C-6 and C-3 positions and substitution degree is 1.10–1.63. The molecular weight sulfated chitosan was determined by viscometric method and the Mark–Houwink equation [η]=10⁻⁵ 4.97 M^0.77. Study of anticoagulant activity showed that chitosan sulfates with lowered molecular weight demonstrated a regular increase of anti-Xa activity like heparins.     

Chalconoid and stilbenoid glycosides from Guibourtia tessmanii

Phytochemical studies on the stem bark of Guibourtia tessmanii yielded a dihydrochalcone glucoside, 2′,4-dihydroxy-4′-methoxy-6′-O-β-glucopyranoside dihydrochalcone and a new stilbene glycoside, 3,5-dimethoxy-4′-O-(β-rhamnopyranosyl-(1→6)-β- glucopyranoside) stilbene besides the known pterostilbene. Their structures were established on the basis of one and two dimensional NMR spectroscopic techniques, FABMS and chemical evidence.     

Timing and magnitude of early Aptian extreme warming: Unraveling primary δO variation in indurated pelagic carbonates at Deep Sea Drilling Project Site 463, central Pacific Ocean

In order to elucidate early Aptian marine paleotemperature evolution across the period of enhanced organic carbon (C_org)-burial [Oceanic Anoxic Event (OAE) 1a], stable isotope analyses were performed on pelagic limestones at Deep Sea Drilling Project Site 463, central Pacific Ocean. The δ¹⁸O data exhibit a distinct anomaly by ~ − 2‰ spanning the OAE 1a interval (i.e., a ~ 6 m-thick, phytoplanktonic C_org-rich unit constrained by magneto-, bio- and δ¹³C stratigraphy). Elucidation of paleotemperature significance of the δ¹⁸O shift is made by taking account of recent Sr/Ca evidence at the same section, which revealed that geochemical signals in carbonate-poor lithologies are relatively unaltered against burial diagenesis. By discriminating δ¹⁸O values from carbonate-poor samples (CaCO₃ contents = 5–30 wt.%), it appears that an abrupt rise in sea-surface temperatures (SSTs) by 8 °C (= − 1.7‰ shift in δ¹⁸O) occurred immediately before OAE 1a, whereas a cooling mode likely prevailed during the peak C_org-burial. In terms of its stratigraphic relationship as to the C_org-rich interval and to a pronounced negative δ¹³C excursion, as well as its timescale, the observed SST rise resembles those associated with the Paleocene–Eocene thermal maximum and, more strikingly, Jurassic Toarcian OAE. This observation is consistent with the hypothesis that these paleoenvironmental events were driven by a common causal mechanism, which was likely initiated by the greenhouse effect via massive release of CH₄ or CO₂ from the isotopically-light carbon reservoir and terminated by a negative productivity feedback.     

Characterisation of the beta-tubulin gene of Cylicocyclus nassatus?

mRNA and genomic DNA were isolated from adult Cylicocyclus nassatus, and the mRNA was reverse transcribed. The cDNA was PCR amplified using degenerate primers designed according to the alignment of the β-tubulin amino acid sequences of other species. To complete the coding sequence, the 3′ end was amplified with the 3′-RACE, and for amplification of the 5′ end the SL1-primer was used. The cDNA of the β-tubulin gene of C. nassatus spans 1429 bp and encodes a protein of 448 amino acids. Specific primers were developed from the cDNA sequence to amplify the genomic DNA sequence and to analyse the genomic organisation of the β-tubulin gene. The complete sequence of the genomic DNA of the β-tubulin gene of C. nassatus has a size of 2652 bp and is organised into nine exons and eight introns. The identities with the exons of the gru-1 β-tubulin gene of Haemonchus contortus range between 79% and 97%.     

Examination of an Oligocene lacustrine ecosystem using C and N stable isotopes

The Late Oligocene (25.8 Ma) Enspel Fossillagerstätte in Westerwald, Germany, contains a comprehensive fossil ecosystem preserved with specimens retaining morphological detail and a concentration of organic material. Stable carbon and nitrogen isotope analyses were used to examine the lacustrine ecosystem preserved in one stratigraphic horizon. These data suggest the presence of several trophic levels, including primary producers (diatoms and higher plants), primary consumers (e.g., tadpoles and insects), and secondary consumers (e.g., the fish species Paleorutilus enspelensis). Terrigenous and aquatic plants were associated with the lowest δ¹³C and δ¹⁵N values (mean plant = − 26.28‰ ± 0.45, 3.18‰ ± 1.04), primary consumers such as flies are one trophic level higher, and carnivores such as fish are yet another level higher. The δ¹⁵N values for P. enspelensis also showed enrichment in ¹⁵N with increasing body length, implying a shift in diet or feeding strategy with size. P. enspelensis and tadpole (Pelobates decheni) samples showed intraorganism fractionation between ‘muscle’ and ‘bone’ tissues. Stable carbon and nitrogen isotope data from the measurement of components (shale, leaves and seeds) common to a number of different stratigraphic horizons showed significant variation between horizons. A number of the features of the stable isotopic data are similar to those relationships seen in modern ecosystems and therefore suggest that stable isotope analyses can contribute to understanding ancient ecosystems.     

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.