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311.
Cationic amphiphilic modified pullulan’s were obtained in two steps: firstly the synthesis of diethylaminoethylpullulan (DEAE-Pullulan) with DS0 = 0.80 in water (all degrees of substitution (DS) are calculated in anhydroglucose units (AGU)) followed by the incorporation of different alkyl chains (C10, C12 and C16) using Hoffmann alkylation reaction. Three alkylated derivatives (Y-Cx-DEAE-Pullulan) were produced with a degree of substitution of alkyl chains (Y = 100 DSCx) of 40 in the case of C10 and C12 and 20 in the case of C16. The three samples contained two functional types: an amine function (DSN), dependent on pH and a quaternary ammonium function (DSN+) linked to a hydrophobic alkyl chain (DSCx). Chemical characterizations were carried out by conductimetric measurements, elemental analysis and 1H NMR. The amphiphilic and associative properties have been confirmed by flow field flow fractionation (F4) coupled on-line with multi-angle laser light scattering (MALLS). The intermolecular associations were observed for DEAE-Pullulan and Y-Cx-DEAE-Pullulan in 0.1 M LiNO3. 相似文献
312.
Yang Zhou Chunguo Qian Depo Yang Cailin Tang Xinjun Xu E-Hu Liu Jingtang Zhong Longping Zhu Zhimin Zhao 《Molecules (Basel, Switzerland)》2021,26(9)
Amomum Villosum Lour. (A. villosum) is a folk medicine that has been used for more than 1300 years. However, study of the polysaccharides of A. villosum is seriously neglected. The objectives of this study are to explore the structural characteristics of polysaccharides from A. villosum (AVPs) and their effects on immune cells. In this study, the acidic polysaccharides (AVPG-1 and AVPG-2) were isolated from AVPs and purified via anion exchange and gel filtration chromatography. The structural characteristics of the polysaccharides were characterized by methylation, HPSEC-MALLS-RID, HPLC, FT-IR, SEM, GC-MS and NMR techniques. AVPG-1 with a molecular weight of 514 kDa had the backbone of → 4)-α-d-Glcp-(1 → 3,4)-β-d-Glcp-(1 → 4)-α-d-Glcp-(1 →. AVPG-2 with a higher molecular weight (14800 kDa) comprised a backbone of → 4)-α-d-Glcp-(1 → 3,6)-β-d-Galp-(1 → 4)-α-d-Glcp-(1 →. RAW 264.7 cells were used to investigate the potential effect of AVPG-1 and AVPG-2 on macrophages, and lipopolysaccharide (LPS) was used as a positive control. The results from bioassays showed that AVPG-2 exhibited stronger immunomodulatory activity than AVPG-1. AVPG-2 significantly induced nitric oxide (NO) production as well as the release of interleukin (IL)-6 and tumor necrosis factor alpha (TNF-α), and upregulated phagocytic capacities of RAW 264.7 cells. Real-time PCR analysis revealed that AVPG-2 was able to turn the polarization of macrophages to the M1 direction. These results suggested that AVPs could be explored as potential immunomodulatory agents of the functional foods or complementary medicine. 相似文献
313.
López-Franco YL de la Barca AM Valdez MA Peter MG Rinaudo M Chambat G Goycoolea FM 《Macromolecular bioscience》2008,8(8):749-757
Structural and physicochemical characteristics of mesquite gum (from Prosopis velutina) were investigated using FT-IR spectroscopic, mass spectrometric and chromatographic methods. Four fractions (F-I, F-IIa, F-IIb and F-III) were isolated by hydrophobic interaction chromatography. The samples were characterized and analyzed for their monosaccharide and oligomers composition by high performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD). L-Arabinose (L-Ara) and D-galactose (D-Gal) were found as the main carbohydrate constituent residues in the polysaccharides from mesquite gum and their ratio (L-Ara/D-Gal) varied within the range 2.54 to 3.06 among the various fractions. Small amounts of D-glucose (D-Glc), D-mannose (D-Man) and D-xylose (D-Xyl) were also detected, particularly in Fractions IIa, IIb and III. Infrared spectroscopy identified polysaccharides and protein in all the samples. Data from mass spectrometry (MALDI-TOF MS) was consistent with the idea that the structure corresponding to the periphereal chains of Fraction I is predominantly a chain of pentoses attached to uronic acid. 相似文献
314.
R. P. Gorshkova V. V. Isakov V. A. Denisenko E. L. Nazarenko E. P. Ivanova L. S. Shevchenko 《Chemistry of Natural Compounds》2008,44(5):549-551
The O-specific polysaccharide of Alteromonas addita type strain KMM 3600T is constructed of trisaccharide repeat units containing L-rhamnose, D-glucose, and D-galactose. It
was established that the O-specific polysaccharide consists of trisaccharide repeat units with the structure →3)-α-D-Galp-(1→3)-α-L-Rhap-(1→3)-α-D-Glcp-(1→ based on monosaccharide analysis, Smith degradation, PMR and 13C NMR spectroscopy, and two-dimensional COSY, HSQC, and HMBC.
Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 445–447, September-October, 2008. 相似文献
315.
NIS/TfOH mediated glycosidation of methyl 3,4,6-tri-O-benzyl-α-d-mannopyranoside with phenyl 2-O-acetyl-3,4,6-tri-O-benzyl-1-thio-α-d-mannopyranoside furnished the corresponding disaccharide derivative in excellent yield and α-selectivity. Zémplen deacetylation of the same followed by reaction with BSP/Tf2O-preactivated phenyl 4,6-O-benzylidene-2,3-di-O-benzyl-1-thio-α-d-mannopyranoside generated methyl 4,6-O-benzylidene-2,3-di-O-benzyl-β-d-mannopyranosyl-(1→2)-3,4,6-tri-O-benzyl-α-d-mannopyranosyl-(1→2)-3,4,6-tri-O-benzyl-α-d-mannopyranoside in very good yield and excellent β-selectivity. Pd/C catalyzed hydrogenation of the latter finally afforded the repeating trisaccharide of Escherichia coli 8 O-antigen as its methyl glycoside. 相似文献
316.
肝素(heparin, Hp)是目前临床应用最为广泛的抗凝剂,是由重复二糖单元组成的多硫酸化酸性直链多糖。低分子量肝素(LMWHs)是以肝素为原料,经过化学或酶降解获得的相对分子质量相对较小的肝素衍生物,相对肝素,它们的出血副作用和免疫原性更小,皮下注射时生物利用度更高。肝素及低分子量肝素具有一系列结构特点,如相对分子质量偏大且有一定分布,多种糖残基同时存在,硫酸酯位置和数量呈现多样化,以及不同工艺产生的特殊残基的种类和含量不一等。该类药物结构的复杂性对分析方法提出了巨大的挑战,也限制了其质量控制提升、工艺优化、临床用药安全和新适应证拓展等。该文以色谱分析方法为中心,从结构分析的不同角度,包括单糖、二糖、寡糖、多糖的识别、组成分析和不同层次,系统地梳理和阐述近年来肝素类药物在色谱分析方法上的进展,并对这些方法的应用范畴、创新性、局限性等进行总结。该文将为肝素类药物的结构分析、质量控制提供较系统的方法学参考,为更多新方法开发提供思路,为更深入地研究肝素类药物结构、拓展其应用提供有力支撑。 相似文献
317.
《Macromolecular bioscience》2017,17(4)
Biocompatible and antibacterial hydrogels have received increasing attention for preventing local bacterial infections. In this study, a type of polysaccharide hydrogels is prepared via the Schiff‐based reaction at physiological conditions. The gelation time and mechanical property of the hydrogels are found to be dependent on the polysaccharide concentration and the polysaccharide weight ratio. 3‐(4,5‐Dimethyl‐thiazol‐2‐yl)‐2,5‐diphenyl tetrazolium bromide assay and live/dead assay indicate that the hydrogels display nontoxicity in vitro. After subcutaneous injection into rats, the hydrogels exhibit an acceptable biocompatibility in vivo. Furthermore, the bacterial inhibition tests by shaking flask method and agar disc‐diffusion method demonstrate that the ceftriaxone‐sodium‐loaded hydrogels have remarkable antibacterial properties in vitro. The in vivo anti‐infective tests further display that the antibiotic‐loaded hydrogels display excellent anti‐infective efficacies in both superficial and deep tissue infection. Consequently, the injectable and biocompatible polysaccharide hydrogels may serve as promising platforms for localized, sustained delivery of antibiotics for preventing local infections.
318.
319.
320.
21世纪的绿色食品包装材料——可食性包装材料 总被引:1,自引:0,他引:1
介绍了新型绿色环保可食性包装材料的特性,并按其制备来源进行了分类,对其现存问题及发展趋势作了概要阐述。 相似文献