Intra-injector methylation of free fatty acids from aerobically and anaerobically cultured Actinobacillus actinomycetemcomitans and Haemophilus aphrophilus.

Free fatty acids from the type strains of anaerobically and aerobically broth-cultured Actinobacillus actinomycetemcomitans and Haemophilus aphrophilus cells were Soxhlet-extracted with hexane. The fatty acids were identified and quantified by gas chromatography and gas chromatography-mass spectrometry after intra-injector derivation with trimethylanilinium hydroxide. This derivatization method, which we propose as suitable for routine use in clinical microbiology, is fast, accurate and sensitive, with low toxicity. Whereas the fatty acid content of A. actinomycetemcomitans was affected by the cultivation atmosphere, i.e. C16:1, decreased under aerobic growth and C16:0 increased, that of the closely related H. aphrophilus was more stable.     

Bactericidal effect of malachite green and red laser on Actinobacillus actinomycetemcomitans

The aim of this study was to investigate the ability of malachite green (MG) combined with a low-power red laser to kill Actinobacillus actinomycetemcomitans and to investigate MG photodegradation after photodynamic therapy (PDT) by optical absorption spectroscopy. The etiology of periodontal disease is that microorganisms form a bacterial biofilm on the surface of the teeth. It is an infectious disease and A. actinomycetemcomitans is considered an important agent in biofilm ecology. Instead of using antibiotics, PDT is an alternative approach to eradicate bacteria. Cultures of A. actinomycetemcomitans were exposed to a 30 mW diode red laser, in the presence or absence of MG. A group of cultures was treated in dark conditions in the presence of MG (0.01% w/v) for 5 min. In the presence of MG, two exposure times for laser irradiation were used: t=3 min (energy dose=5.4 J/cm(2)), and t=5 min (energy dose=9 J/cm(2)). The samples were diluted and bacterial colonies were counted and converted into colony forming units. Absorption spectra of the bacterial suspensions, MG, MG-stained bacterial suspensions, and photosensitized bacterial suspensions were obtained. A. actinomycetemcomitans can be photoinactivated by a red laser in the presence of MG. Significant differences were observed between the two energy doses used (p<0.05). Red laser alone and MG alone were not able to kill bacteria. Optical absorption showed that MG is photobleached after irradiation. These results indicate that A. actinomycetemcomitans can be photosensitized by red laser combined with MG and that the dye is photodegraded following irradiation.     

Amphipilic and mesogenic carbohydrates XII. New thermotropic mesogens based on perfluoroalkyl-substituted carbohydrates

In continuing studies of amphiphilic and mesogenic carbohydrates, the mesomorphic properties of a new group of perfluoroalkylated amphiphilic mesogens are discussed. Smectic A phases dominate the mesomorphic behaviour of the new materials, but one compound exhibits a columnar mesophase and three others have SmA-SmC* transitions. The synthesis of these materials has already been reported and involved dithionite-mediated O- and S-perfluoroalkylations with 1-iodoperfluoroalkanes.     

Amphipilic and mesogenic carbohydrates XII. New thermotropic mesogens based on perfluoroalkyl-substituted carbohydrates

In continuing studies of amphiphilic and mesogenic carbohydrates, the mesomorphic properties of a new group of perfluoroalkylated amphiphilic mesogens are discussed. Smectic A phases dominate the mesomorphic behaviour of the new materials, but one compound exhibits a columnar mesophase and three others have SmA-SmC* transitions. The synthesis of these materials has already been reported and involved dithionite-mediated O- and S-perfluoroalkylations with 1-iodoperfluoroalkanes.     

Kinetic analysis of interaction between lipopolysaccharide and biomolecules

Lipopolysaccharide (LPS) is a major component of the outer membrane of all gram-negative bacteria. It interacts with some biomolecules and triggers a toxic reaction. In this paper, we studied the interaction between LPS from Salmonella Minnesota and some biomolecules using a surface plasmon resonance (SPR) biosensor. Biomolecules were immobilized on a CM5 sensor chip using the amino coupling method and LPS was injected over the immobilized surfaces. The affinity constant K_A of LPS with serum albumin, hemoglobin, chitosan and lysozyme was 2.36 × 10⁷, 2.03 × 10⁸, 7.58 × 10⁶, 2.82 × 10⁴ L·mol⁻¹, respectively. However, LPS could not interact with ferritin. __________ Translated from Chinese Journal of Analytical Chemistry, 2007, 35(5): 677–680 [译自: 分析化学]     

Differentiation between sulfoaildenafil and its analogs

An analog of aildenafil, which is a potent and highly selective inhibitor of phosphodiesterase 5, was found in a dietary supplement marketed for enhancement of sexual function. The compound was isolated by silica gel column chromatography, and its structure was identified by means of 13C-NMR spectrometry, 1H-NMR spectrometry, high-resolution MS, and X-ray structure determination. The compound was identified to be sulfoaildenafil (other names: thioaildenafil, dimethyl sildenafil thione, and thiomethisosildenafil). Sulfoaildenafil is very similar to the compound thiohomosildenafil. As it is difficult to distinguish between them by LC-photodiode array detector analysis, ultra-performance LC (UPLC)/MS, ion trap LC/MS/MS (LC/IT-MS/MS), and GC/MS were performed. The mass spectra of thiohomosildenafil by UPLC/MS and LC/IT-MS/MS showed mass fragments of m/z 58, 72, and 355, and the mass spectrum by GC/MS showed mass fragments of m/z 56, 72, and 420. Some of these fragments had low intensities, but they were useful for distinguishing between the two compounds. The relationship between aildenafil (other names: dimethylsildenafil and methisosildenafil) and homosildenafil is similar to that between sulfoaildenafil and thiohomosildenafil. Therefore, these compounds were also examined.     

Antimicrobial and wound healing activities of electrospun nanofibers based on functionalized carbohydrates and proteins

The anti-adhesion, anti-growth and the anti-penetration of bacteria, specifically multidrug-resistant bacteria, should be taken into consideration when designing promising wound dressings for infected wounds such as diabetic foot ulcers. Wound dressings composed of natural polymeric nanofibers such as functionalized cellulose, chitosan, alginate, hyaluronic acid, dextrin and cyclodextrin with appropriate antimicrobial and skin reconstruction properties are suitable alternatives that can accelerate wound healing and remove microbial infections. For instance, to improve the release profile of antibacterial agents such as metal nanoparticles and antibiotics, water-soluble polymers like polyethylene oxide and polyvinylpyrrolidone may be incorporated into polymeric nanofiber scaffolds. This review, therefore, addresses the current status and future challenges of antibacterial activities of nanofiber scaffolds composed of some of the natural occurring polymers.

     

Highly enantioselective Rh-catalyzed hydrogenation based on phosphine-phosphite ligands derived from carbohydrates.

A new class of efficient catalysts was developed for the asymmetric hydrogenation of alpha,beta-unsaturated carboxylic acid derivatives by synthesizing a series of novel phosphine-phosphite ligands (4a-d) derived from readily available D-(+)-xylose. Excellent enantioselectivities (> 99%) were achieved under very mild reaction conditions (1 bar H(2) and 20 degrees C). Varying the biphenyl substituents in the phosphite moiety greatly affected the enantioselectivity in the hydrogenation reactions. The results also indicate that the sense of enantioselectivity is mainly controlled by the configuration of the phosphite moiety. (31)P[(1)H] NMR and kinetic studies on intermediates of the catalytic cycle show that the [Rh(P(1)-P(2))(enamide)]BF(4) species is the resting state and that the rate dependence is first order in rhodium and hydrogen pressure and zero order in enamide concentration.     

A study of properties of porous carbon based on phenol-formaldehyde resin with carbohydrates

Structure and some physical properties of nanoporous carbon powders produced by pyrolysis of mixtures of phenol-formaldehyde resin with saccharose or cellulose were studied.     

The interaction between the gut microbiota and dietary carbohydrates in nonalcoholic fatty liver disease

Imbalance between fat production and consumption causes various metabolic disorders. Nonalcoholic fatty liver disease (NAFLD), one such pathology, is characterized by abnormally increased fat synthesis and subsequent fat accumulation in hepatocytes^1,2. While often comorbid with obesity and insulin resistance, this disease can also be found in lean individuals, suggesting specific metabolic dysfunction². NAFLD has become one of the most prevalent liver diseases in adults worldwide, but its incidence in both children and adolescents has also markedly increased in developed nations^3,4. Progression of this disease into nonalcoholic steatohepatitis (NASH), cirrhosis, liver failure, and hepatocellular carcinoma in combination with its widespread incidence thus makes NAFLD and its related pathologies a significant public health concern. Here, we review our understanding of the roles of dietary carbohydrates (glucose, fructose, and fibers) and the gut microbiota, which provides essential carbon sources for hepatic fat synthesis during the development of NAFLD.Subject terms: Metabolic syndrome, Metabolic syndrome     

Bonding between Cu(II) complexes with celluloses and related carbohydrates

The electron paramagnetic resonance spectra of cupriethylenediamine dihydroxide and cupriammonium hydroxide when complexed with cellulose, hydrocellulose, maltose, and dextrose at ?160°C and at room temperature are reported. The spectra of the complexes formed indicate that the interaction is not physical but a chemical one, and the covalent character of the copper ligand has become comparatively weaker. The possibility of weak axial interaction for these complexes is shown to be unlikely, and it is proved that the nature of the interaction is a strong chemical bond between the copper and the 2,3-hydroxyl groups of the pyranoside ring of the ligand.     

基于花生四烯酸代谢通路研究水飞蓟素对脂多糖诱导炎症模型影响

以脂多糖类似物(KLA)诱导的RAW264.7细胞为研究对象,采用代谢组学研究手段,研究水飞蓟素对脂多糖诱导炎症模型中花生四烯酸代谢通路的影响。以超高效液相色谱-三重四极杆质谱联用为平台,对不同浓度水飞蓟素作用下KLA诱导RAW264.7炎症细胞分泌的类二十烷酸代谢物进行定量分析,通过考察主成分分析(PCA)、正交偏最小二乘法判别分析(OPLS-DA)的VIP值和Kruskal-Wallis秩和检验结果显著性差异(P)值筛选代谢标记物。建立了59种类二十烷酸(含15种同位素内标)在5 min内实现快速分离的液相色谱-质谱联用方法;确定了细胞存活率在58%~80%的水飞蓟素浓度为50~150μmol/L;筛选出数据处理结果同时满足变异权重参数(VIP)值1且结果P值0.05的类二十烷酸代谢标记物12-OxoLeukotriene B4(12-OxoLTB4);通过分析柱状图和炎症信号通路,确定水飞蓟素借助其抗氧自由基特性发挥抗炎作用,通过抑制脂氧合酶-5(5-LOX)的活性及阻断5-LOX代谢通路中产生氧自由基的脂质过氧化反应来减少氧自由基及过氧化物的形成。综上所述,所建立的方法能快速准确地定量分析多种类二十烷酸,并从代谢组学角度解释了水飞蓟素的抗炎机制。     

Differentiation between dexamethasone and betamethasone in a mixture using multiple mass spectrometry

Direct gas chromatographic methods to analyse phenylurea pesticides are discouraged by the thermal instability of these compounds, that in conventional hot splitless inlet systems leads to extensive and irreproducible formation of isocyanates and amines. However a careful control of the operating conditions, like the inlet temperature, the pressure and the presence of suitable chemical additives (as acetic acid, low-molecular-mass amines, organic anhydrides) can either: (i) minimise the thermal decomposition enabling the direct GC-MS analysis of phenylureas, or (ii) lead to reproducible conversion to isocyanates. Experimental design was employed to study the effect of the experimental variables on the thermal transformation of phenylurea pesticides in splitless inlet system. Two strategies were alternatively optimised: (i) the minimisation of degradation reactions to increase the signal of phenylureas; (ii) the maximisation of the degradation to isocyanates that are in turn determined. The maximal yields in isocyanate were obtained with high inlet temperatures, low carrier flows in the injection phase and the presence of acetic anhydride. By contrast, the use of relatively low inlet temperatures, high carrier flows during the injection and the presence of an amine maximise the response of the parent compounds.     

Quantitative estimation of interaction between carbohydrates and concanavalin A by surface plasmon resonance biosensor

We measured the affinity of more than 20 sugars with concanavalin A (ConA) by an optical biosensor (surface plasmon resonance sensor) using asialofetuin (ASF) as an immobilized binding partner of ConA. We determined kinetic parameters of the effects of sugars on the dissociation of ConA from ASF quantitatively, and the structural requirements of the functional groups of sugars for binding with ConA. We found that the affinity of ConA for sugars is dependent on its conformation induced by interaction with the binding partner. In addition, the results showed that optical biosensor system is well mimics the interaction of ConA with sugars in biomembrane.