首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
A galactomannoglucan (GMG) with an estimated weight-average molar mass of 1.5 × 105 was obtained from an aqueous extract of the mesocarp of fruits of Arecastrum romanzoffianum (Cham.) Becc. by fractionation by Sephacryl S-300 HR and Sephadex G-25. Chemical and spectroscopic studies indicated that GMG has a chain of (1  4)-linked β-d-mannopyranosyl residues, a chain of (1  3)-linked β-d-galactopyranosyl residues, a chain of (1  4)-linked α-d-glucopyranosyl residues, repeating units of β-d-galactopyranosyl-(1  4)-β-d-mannopyranosyl and β-d-mannopyranosyl-(1  4)-α-d-glucopyranosyl and terminal residues of d-galactopyranosyl and d-glucopyranosyl which comprised galactose, mannose and glucose in the molar ratio of 10:37:53. The polysaccharide exhibited significant antiinflammatory activity against carrageenan-induced mouse paw oedema.  相似文献   

2.
A polysaccharide fraction, J6, was isolated from the hot-water extract of flowers of oleander Nerium indicum Mill., using ethanol precipitation, cetyltrimethylammonium bromide (CTAB) complexing, anion-exchange chromatography and gel permeation chromatography. J6 was found to contain l-rhamnose, l-arabinose, d-galactose, and d-galacturonic acid, in the ratio of 10.1:49.8:30.1:10.0. Its structure was investigated by methylation analysis, periodate oxidation, Smith degradation, partial acid hydrolysis, electrospray ionization mass spectrometry and NMR spectroscopic methods. It was found that J6 is an RG-I type polysaccharide, which contains a rhamnogalacturonan backbone, with various branches attached to O-4 of l-rhamnose. The branches probably involve (1  4)-β-d-galactan, branched l-arabino-(1  3)(1  6)-β-d-galactan, and (1  5)-α-l-arabinan. J6 stimulated NO production of macrophage RAW264.7 cells in a preliminary test.  相似文献   

3.
《Process Biochemistry》2010,45(9):1550-1556
Ginsenoside Rb1 is the most abundant ginsenoside in Panax (ginseng). The hydrolysis of this ginsenoside produces compound K, the biologically active ginsenoside of ginseng. We previously identified a fungus Paecilomyces Bainier sp. 229 (sp. 229), which can efficiently convert ginsenoside Rb1 to compound K. In this report, the ginsenoside hydrolyzing β-glucosidases were isolated from sp. 229 and the pathway of the biotransformation of ginsenoside Rb1 to compound K by sp. 229 was investigated. Based on reverse-phase HPLC and TLC analysis, we found the main metabolic pathway is as follows: ginsenoside Rb1  ginsenoside Rd  ginsenoside F2  compound K. Moreover, the results showed that there were other metabolic pathways: ginsenoside Rb1  ginsenoside XVII  ginsenoside F2  compound K and ginsenoside Rb1  ginsenoside Rg3  ginsenoside Rh2. These processes would allow the specific bioconversion of ginsenoside Rb1 to various ginsenosides using an appropriate combination of specific microbial enzymes.  相似文献   

4.
A galactoglucomannan (GGM) with an estimated weight-average molar mass of 3.5 × 105 was obtained from an aqueous extract of the mesocarp of fruits of Acrocomia aculeata (Jacq.) Lodd. by fractionation by Sephacryl S-300 HR and Sephadex G-25. Chemical and spectroscopic studies indicated that GGM has a main chain of (1  4)-linked β-d-mannopyranosyl residues attached to an initial chain of (1  3)-linked β-d-galactopyranosyl residues and a terminal chain of (1  4)-linked α-d-glucopyranosyl residues which comprised galactose, glucose and mannose in the molar ratio of 18:22:60. The adjuvant potential of the polysaccharide on the cellular immune response against ovalbumin antigen was investigated using in vivo assays.  相似文献   

5.
We consider the spread of an epidemic through a population divided into n sub-populations, in which individuals move between populations according to a Markov transition matrix Σ and infectives can only make infectious contacts with members of their current population. Expressions for the basic reproduction number, R0, and the probability of extinction of the epidemic are derived. It is shown that in contrast to contact distribution models, the distribution of the infectious period effects both the basic reproduction number and the probability of extinction of the epidemic in the limit as the total population size N  ∞. The interactions between the infectious period distribution and the transition matrix Σ mean that it is not possible to draw general conclusions about the effects on R0 and the probability of extinction. However, it is shown that for n = 2, the basic reproduction number, R0, is maximised by a constant length infectious period and is decreasing in ?, the speed of movement between the two populations.  相似文献   

6.
The cell wall of Saccharomyces cerevisiae is an important source of β-d-glucan, a glucose homopolymer with immunostimulant properties. The standard methodologies described for its extraction involve acid and alkaline washings, which degrade part of its glucose chains and reduce the final yield. In the present study, an optimized methodology for extraction of β-d-glucan from S. cerevisiae cells, involving sonication and enzyme treatment, with a yield of 11.08 ± 0.19%, was developed. The high-purity (1  3)(1  6)-β-d-glucan was derivatized to carboxymethyl-glucan (CM-G). In vitro tests with CM-G in Chinese hamster epithelial cells (CHO-k1) did not reveal any cytotoxic or genotoxic effects or influences of this molecule on cell viability. The method described here is a convenient alternative for the extraction of (1  3)(1  6)-β-d-glucan under mild conditions without the generation of wastes that could be potentially harmful to the environment.  相似文献   

7.
The tailed frog Ascaphus truei Stejneger, 1899 is the most primitive extant anuran and the sister taxon to the clade of all other living frogs. The species occupies two disjunct ranges in the Northwest region of North America: the Cascade Mountains and coastal area from British Columbia to Northern California, and an inland range in the northern Rocky Mountains and the Blue and Wallowa mountains. A previous study led to the isolation of eight peptides with antimicrobial activity (termed the ascaphins) from skin secretions of A. truei from the coastal range. The present study has used peptidomic analysis to identify the products of orthologous ascaphin genes in electrically-stimulated skin secretions from inland range specimens. Structural characterization of the peptides demonstrated that ascaphins from the inland range contained the following amino acid substitutions compared with orthologs from the coastal range frogs: ascaphin-1 (Ala12  Glu), ascaphin-3 (Asp4  Glu), ascaphin-4 (Ala19  Ser), ascaphin-5 (Lys12  Thr), and ascaphin-7 (Gly8  Ser and Ser20  Asn). Orthologs of ascaphins-2, -6, and -8 were not identified but a paralog of ascaphin-5, identical to ascaphin-5 from coastal range frogs, was found. The data support the claims, derived from analysis of the nucleotide sequences of mitochondrial genes, that the inland populations of the tailed frog should be recognized as a distinct species, the Rocky Mountain tailed frog Ascaphus montanus and that the divergence of the species from A. truei probably occurred in the late Miocene (approximately 10 Mya).  相似文献   

8.
The influence of dissolved oxygen tension (DOT) on the production of extracellular (1  3)- and (1  6)-β-glucanases by the fungus Acremonium sp. IMI 383068 was investigated in batch culture. The controlled DOT levels at which cultures were grown affected the measured (1  3)-β-glucanase specific activities, but these effects were less marked on the measured (1  6)-β-glucanase specific activities. There appeared to be no direct link between the branching frequency of the fungus as reflected by its hyphal growth unit, and changing DOT levels. Whether pustulan or scleroglucan were used as the sole carbon source also affected production of these enzymes and their response to varying DOT. The measured (1  3)-β-glucanase specific activities were generally higher with scleroglucan, mainly because of the production of an extra active (1  3)-β-glucanase whereas pustulan grown cells produced a corresponding inactive protein with an identical electrophoretic mobility by SDS-PAGE and N-terminal amino acid sequence. With pustulan grown cells, DOT levels had comparatively little influence on the optimal measured specific activities of the (1  3)-β-glucanases, while with scleroglucan, they increased as DOT increased.  相似文献   

9.
Four triterpene saponins, agrostemmosides A–D were isolated from the methanol extract of Agrostemma gracilis. The structures of the compounds were determined as 3-O-β-d-xylopyranosyloleanolic acid 28-O-β-d-glucopyranosyl-(1  2)-[β-d-xylopyranosyl-(1  6)]-β-d-glucopyranosyl-(1  6)-β-d-glucopyranosyl ester, 3-O-α-l-rhamnopyranosyl-(1  2)-β-d-xylopyranosyloleanolic acid 28-O-β-d-glucopyranosyl-(1  2)-[β-d-xylopyranosyl-(1  6)]-β-d-glucopyranosyl-(1  6)-β-d-glucopyranosyl ester, 3-O-β-d-xylopyranosylechinocystic acid 28-O-β-d-glucopyranosyl-(1  2)-β-d-glucopyranosyl-(1  6)-β-d-glucopyranosyl ester, 3-O-β-d-xylopyranosylechinocystic acid 28-O-β-d-glucopyranosyl-(1  2)-[β-d-xylopyranosyl-(1  6)]-β-d-glucopyranosyl-(1  6)-β-d-glucopyranosyl ester by a combination of one- and two-dimensional NMR techniques, and mass spectrometry. To the best of our knowledge this is the first phytochemical report on A. gracilis, and echinocystic acid saponins were encountered for the first time in Caryophyllaceae family.  相似文献   

10.
A novel polysaccharide named CBP-1 was isolated from the fruiting body of cultured Cordyceps militaris by alkaline extraction as well as anion-exchange and gel-permeation chromatography. Its structural features were investigated by a combination of chemical and instrumental analysis approaches, including partial hydrolysis, methylation analysis, HIO4 oxidation-Smith degradation, GC–MS, 13C NMR, HPAEC-PAD and FT-IR. The results indicated that CBP-1 has a backbone of (1  4)-α-d-mannose residues which occasionally branches at O-3. The branches were mainly composed of (1  4)-α-d-glucose residues and (1  6)-β-d-galactose residues, and terminated with β-d-galactose residues. In the in vitro antioxidant assay, CBP-1 was found to possess the hydroxyl radical-scavenging activity with an IC50 value of 0.638 mg/ml.  相似文献   

11.
Four flavonol glycosides isolated from non-flowering leafy shoots of Iberis saxatilis (Brassicaceae) were characterised by spectroscopic and chemical methods as saxatilisins A–D, the 3-O-β-d-glucopyranosyl-(1  3)-α-l-rhamnopyranosyl-(1  2)[β-d-glucopyranosyl-(1  2)-α-l-rhamnopyranosyl-(1  6)]-β-d-glucopyranoside, 3-O-β-d-glucopyranosyl-(1  3)-α-l-rhamnopyranosyl-(1  2)[α-l-rhamnopyranosyl-(1  6)]-β-d-glucopyranoside, 3-O-(6-O-E-sinapoyl)-β-d-glucopyranosyl-(1  3)-α-l-rhamnopyranosyl-(1  2)[β-d-glucopyranosyl-(1  2)-α-l-rhamnopyranosyl-(1  6)]-β-d-glucopyranoside, and 3-O-(6-O-E-feruloyl)-β-d-glucopyranosyl-(1  3)-α-l-rhamnopyranosyl-(1  2)[β-d-glucopyranosyl-(1  2)-α-l-rhamnopyranosyl-(1  6)]-β-d-glucopyranoside of isorhamnetin (3,5,7,4′-tetrahydroxy-3′-methoxyflavone), respectively. Analysis of 2JHC correlations detected with the H2BC (heteronuclear two-bond correlation) pulse sequence aided the unambiguous assignment of glycosidic resonances in the 1H and 13C NMR spectra of these compounds. Saxatilisins A, C, and D, are the first flavonol glycosides to be described with a pentasaccharide chain at a single glycosylation site. Several pentaglycosides of kaempferol and quercetin, tentatively assigned as saxatilisin analogues from LC–MS/MS analyses, were present as minor constituents of the extracts.  相似文献   

12.
Thirteen polysaccharides isolated from an extract of the aerial portions of Astragalus mongholics Bunge demonstrated immunomodulating activity against Peyer’s patch immunocompetent cells. Nine of the active polysaccharide fractions were composed of either arabinogalactans, pectic arabinogalactans or pectins. The activities of the arabinogalactans and pectic arabinogalactans were associated with β-d-(1  3)-galactan moieties branched with β-d-(1  6)-galactooligosaccharide side-chains having degrees of polymerization of 8 or less. Degradation of the β-d-(1  3)-galactan or β-d-(1  6)-galactosyl side-chains in the arabinogalactans significantly decreased immunomodulating activity. Rhamnogalacturonan I (RG-I) with β-d-(1  3,6)-galactosyl side-chains having terminal β-d-GlcA showed activity in the pectin-enriched fractions. Interestingly, the terminal GlcA was not required for activity of the arabinogalactan-enriched fractions, suggesting at least two different immunomodulating structures.  相似文献   

13.
Community-based assessment of protozoa is usually performed at a taxon-dependent resolution. As an inherent ‘taxon-free’ trait, however, body-size spectrum has proved to be a highly informative indicator to summarize the functional structure of a community in both community research and monitoring programs in aquatic ecosystems. To demonstrate the relationships between the taxon-free resolution of protozoan communities and water conditions, the body-size spectra of biofilm-dwelling protozoa and their seasonal shift and environmental drivers were explored based on an annual dataset collected monthly from coastal waters of the Yellow Sea, northern China. Body sizes were calculated in equivalent spherical diameter (ESD). Among a total of 8 body-size ranks, S2 (19–27 μm), S3 (28–36 μm), S4 (37–50 μm) and S5 (53–71 μm) were the top four levels in frequency of occurrence, while rank S1 (13–17 μm), S2 and S4 were the dominant levels in abundance. These dominants showed a clear seasonal succession: S2/S4 (spring)  S2/S4 (summer)  S4 (autumn)  S2 (winter) in frequency of occurrence; S1 (spring)  S4 (summer)  S2 (autumn)  S1 (winter) in abundance. Bootstrapped average analysis showed a clear seasonal shift in body-size spectra of the protozoa during a 1-year cycle, and the best-matching analysis demonstrated that the temporal variations in frequency of occurrence and abundance were significantly correlated with water temperature, pH, dissolved oxygen (DO), alone or in combination with chemical oxygen demand (COD) and nutrients. Thus, the body-size spectra of biofilm-dwelling protozoa were seasonally shaped and might be used as a time and cost efficient bioindicator of water quality in marine ecosystems.  相似文献   

14.
Hymenaea coubaril L. seeds are widely used by the population for the treatment of several ailments. Despite its popular use, no other phytochemical studies had been carried out about “Jatobá” seeds. For this reason, this is the first study on the matter and it was carried out with the purpose of finding and identifying the molecules that constitute this seed. This work presented the isolation and elucidation of two new biscoumarins from H. coubaril L. seeds. The new compounds: hymenain 7-O-β-glucopyranosyl-(1′′′  2′′)-O-α-apiofuranosyl-(1′′′′  2′′′)-O-α-galactopyranoside (1) and hymenain 7-O-β-glucopyranosyl-(1′′′  2′′)-O-α-apiofuranoside (2). Their structures were elucidated by extensive 1D and 2D NMR experiments, IR and electrospray high resolution mass spectrometry (ESI-HRMS).  相似文献   

15.
Two triterpenoid saponins have been isolated from the seed kernels of Entada rheedii. Their structures have been established using 1D- and 2D-NMR and mass spectrometry as 3-O-β-d-xylopyranosyl-(1  3)-O-α-l-arabinopyranosyl-(1  6)-2-acetylamino-2-deoxy-β-d-glucopyranosylentagenic acid 28-O-β-apiofuranosyl-(1  3)-β-d-xylopyranosyl-(1  2)-β-d-glucopyranoside (Rheediinoside A, 1) and 3-O-β-d-glucopyranosyl-(1  3)-O-[β-d-xylopyranosyl-(1  3)-α-l-arabinopyranosyl-(1  6)]-2-acetylamino-2-deoxy-β-d-glucopyranosylentagenic acid 28-O-β-apiofuranosyl-(1  3)-β-d-xylopyranosyl-(1  2)-β-d-glucopyranoside (Rheediinoside B, 2). Compounds 1 and 2 were tested for their antiproliferative activity against T98G, A431, PC3 and B16-F1 cell lines, and further for their antioxidant properties. Moderate cytotoxic potency and antioxidant properties were found for these compounds whereas Rheediinoside B was in all assays more active than Rheediinoside A.  相似文献   

16.
A glucuronoxylan was extracted from the holocellulose of Eucalyputus globulus wood with 10% KOH and subjected to hydrolysis by a commercial cellulase preparation “Meicelase”. Neutral xylooligosaccharides liberated were analyzed by size exclusion chromatography. Aldouronic acids liberated were purified by preparative anion exchange chromatography. Their structures were studied by monosaccharide analysis, comparison of volume distribution coefficients (Dvs) in anion exchange chromatography with those of the authentic samples, and 1H and 13C NMR spectroscopy, resulting in the characterization of seven aldouronic acids including a novel one containing galactose residue.O-β-d-Xylp-(1  4)-[O-(4-O-Me-α-d-GlcAp)-(1  2)]-O-β-d-Xylp-(1  4)-O-β-d-Xylp-(1  4)-d-XylO-(4-O-Me-α-d-GlcAp)-(1  2)-O-β-d-Xylp-(1  4)-O-β-d-Xylp-(1  4)-d-XylO-(4-O-Me-α-d-GlcAp)-(1  2)-O-β-d-Xylp-(1  4)-d-XylO-β-d-Xylp-(1  4)-O-β-d-Xylp-(1→3)-O-α-l-Rhap-(1  2)-O-α-l-GalAp-(1  4)-d-XylO-β-d-Xylp-(1  4)-O-β-d-Xylp-(1  3)-O-α-l-Rhap-(1  2)-d-GalAO-β-d-Xylp-(1  3)-O-α-l-Rhap-(1  2)-O-α-d-GalAp-(1  4)-d-XylO-β-d-Galp-(1  2)-O-(4-O-Me-α-d-GlcAp)-(1  2)-O-β-d-Xylp-(1  4)-O-β-d-Xylp-(1  4)-d-Xyl.The oligosaccharides liberated provide information on multiplicity of xylanases secreted by Trichoderma viride. The presence of the last aldouronic acid shows a structural feature of E. globulus xylan.  相似文献   

17.
Two oligosaccharides (1, 2) and a stereoisomer of di-p-coumaroylquinic acid (3) were isolated from the aerial parts of Tribulus terrestris along with five known compounds (48). The structures of the compounds were established as O-β-d-fructofuranosyl-(2  6)-α-d-glucopyranosyl-(1  6)-β-d-fructofuranosyl-(2  6)-β-d-fructofuranosyl-(2  1)-α-d-glucopyranosyl-(6  2)-β-d-fructofuranoside (1), O-α-d-glucopyranosyl-(1  4)-α-d-glucopyranosyl-(1  4)-α-d-glucopyranosyl-(1  2)-β-d-fructofuranoside (2), 4,5-di-p-cis-coumaroylquinic acid (3) by different spectroscopic methods including 1D NMR (1H, 13C and DEPT) and 2D NMR (COSY, TOCSY, HMQC and HMBC) experiments as well as ESI-MS analysis. This is the first report for the complete NMR spectral data of the known 4,5-di-p-trans-coumaroylquinic acid (4).The antioxidant activity represented as DPPH free radical scavenging activity was investigated revealing that the di-p-coumaroylquinic acid derivatives possess potent antioxidant activity so considered the major constituents contributing to the antioxidant effect of the plant.  相似文献   

18.
Vincristine is a natural vinca alkaloid widely used in paediatric cancer treatment. Vincristine pharmacokinetics has been already studied, but few data are available in paediatric populations. A sensitive and specific liquid chromatography–tandem mass spectrometry (LC/MS/MS) method was developed for the quantification of vincristine in plasma in order to investigate pharmacokinetics in a paediatric population. Two hundred microliters of plasma was added to vinblastine, used as internal standard. Chromatographic separation was achieved on a C8 HPLC column (Phenomenex Luna 50 mm × 2.0 mm, 3.0 μm) with a mobile phase gradient at a flow rate of 0.2 ml/min. Quantification was performed using the transition of 825.4  765.4 (m/z) for vincristine and 811.4  751.4 (m/z) for vinblastine. Chromatographic separation was achieved in 8 min. The limit of quantification was 0.25 ng/ml with a precision of 10.2% and an accuracy of 99.6%. The calibration curve was linear up to 50.0 ng/ml. Intra-day precision and accuracy ranged from 6.3% to 10% and from 91.9% to 100.8%, respectively. Inter-assay precision and accuracy ranged from 3.8% to 9.7% and from 93.5% to 100.5%, respectively. No significant matrix effect was observed for vincristine. A rapid, specific and sensitive LC/MS/MS method for quantification of vincristine in human plasma was developed and is now successfully applied for pharmacokinetic studies in paediatric patients.  相似文献   

19.
Two new penterpenoid saponins, hemsloside-Ma4 (1) hemsloside-Ma5 (2), and a new diterpenoid glycoside, hemsloside-Ma6 (3), were isolated from the rhizomes of Hemsleya chinensis. By detailed analysis of the NMR spectra and chemical methods, the structures of new compounds were determined to be 3-O-β-l-arabinopyranosyl-(1  3)-O-(6′-methyl ester)-β-d-glucuropyranosyl-oleanolic acid-28-O-β-d-glucopyranosyl-(1  6)-O-β-d-glucopyranoside (1), 3-O-β-l-arabinopyranosyl-(1  3)-O-(6′-methyl ester)-β-d-glucuropyranosyl-oleanolic acid-28-O-β-d-xylopyranosyl-(1  6)-O-β-d-glucopy-ranoside (2), and 13ϵ-hydroxylabda-8(17), 14-dien-18-oic acid-18-O-α-l-rhamnopyranosyl-(1  2)-O-β-d-glucopyranosyl-(1  4)-O-α-l-rhamnopyranoside (3). Diterpenoid-type compound (3) was isolated from Hemsleya genus for the first time.  相似文献   

20.
Three new oleanane-type saponins, leptocarposide B-D (13), were isolated from the whole plant of Ludwigia leptocarpa (Nutt.) Hara, together with ten known compounds 4–13.The structures of these compounds were determined by interpretation of their spectral data, mainly HR-TOFESIMS, 1D-NMR (1H, 13C) and 2D-NMR (1H–1H COSY, HSQC, HMBC, and NOESY), and by comparison with the literature data. The structures of the new compounds were established as 28-O-β-d-xylopyranosyl-(1  4)-α-l-rhamnopyranosyl-(1  2)-[α-l-arabinopyranosyl-(1  3)]-4-O-(3′-hydroxybutanoyloxy-3-hydroxybutanoyloxy)-β-d-fucopyranosyl zanhic acid (1); 3-O-β-d-glucopyranosyl-28-O-β-d-xylopyranosyl-(1  4)-α-l-rhamnopyranosyl-(1  2)-4-O-(3′-hydroxybutanoyloxy-3-hydroxybutanoyloxy)-β-d-fucopyranosyl medicagenic acid (2); 3-O-β-d-glucopyranosyl-(1  4)-β-d-glucopyranosyl-28-O-β-d-xylopyranosyl-(1  4)-α-l-rhamnopyranosyl-(1  2)-[α-l- arabinopyranosyl-(1  3)]-4-O-(3′-hydroxybutanoyloxy-3-hydroxybutanoyloxy)-β-d-fucopyranosyl zanhic acid (3).  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号