AHP-based procedure for optimization of microwave-assisted blackberry sugar osmotic process

Due to the limitations of single index analysis, the merits and demerits of microwave-assisted permeation process cannot be comprehensively evaluated. However, the analytical hierarchy process (AHP) was applied to optimize the conditions of microwave-assisted diffusion of sugar in blackberry. In this paper, the results of a single-factor experiment were compared with blackberry preserved after the treatment of microwave. An orthogonal rotation test procedure was designed to calculate the composite score of preserved blackberry fruit using AHP, and to determine the optimum processing conditions based on sugar osmosis characteristics. The results showed that the sugar content, vitamin C (VC) content, and color difference of treated blackberry increased with the increase of microwave power, the residence time, and the resulting sugar concentration. The composite grade points are listed to show that the optimum results were as follows: power level, the residence time, and the sugar concentration were, respectively, 210?W, 12?min, and 35%.     

An effective surfactant-free isolation procedure for single-wall carbon nanotubes

An optimised isolation procedure of single-wall carbon nanotubes (SWNTs) from a SWNT soot without using any surfactant is reported. Amorphous carbon and small graphitic particles were washed away with N-methyl-2-pyrrolidone (NMP) and acetone. A large amount of graphite-coated metal particles were removed with the oxidation of the SWNT material with HNO₃ (6.5 and 4 M) and by washing the oxidised SWNT material with a mixture of methanol (MeOH) and deionised water. The isolated material was investigated with transmission electron microscopy (TEM) and Raman scattering (647.1 and 532 nm). An elemental analysis of the content of Co and Ni in the SWNT samples isolated at different steps of the isolation procedure was performed. On the basis of the TEM images and elemental analysis it was estimated that the purified material contains more than 75 wt.% of SWNTs.     

Use of ionic liquids for biocatalytic synthesis of sugar derivatives

Sugar‐based compounds are widely used in pharmaceuticals, cosmetics, detergents and food. They are mainly produced by chemical methods, but the use of enzymes as ‘a greener alternative’ to organic synthesis has been investigated for more than 20 years. Due to the low polar substrate solubility in organic solvents compatible with enzymes, research has focused on the application of substitutes for biocatalysis, especially ionic liquids (ILs). After introducing the main properties of ILs and especially their ability to solubilize sugars, this review focuses on one of their applications, the biocatalytic synthesis of carbohydrate derivatives. In this context, they can be used in pure IL systems, in IL/IL systems or in IL/organic solvent systems. Finally, this review provides an update on the environmental fate of ILs. Their exploitation in ‘green’ processes is still limited due to their low degradability but research is currently under way to design new more ‘eco‐friendly’ ILs. Copyright © 2012 Society of Chemical Industry     

Infrared spectrophotometric procedure for determining azelaaldehydic acid derivatives

A convenient and accurate infrared procedure was developed for determining the conversion of azelaaldehydic esters to acetals by measuring disappearance of the aldehydic C−H stretching vibration at 2720 cm⁻¹ (3.68μ). No. Utiliz. Res. Dev. Div., ARS, USDA.     

5-O-取代木犀草素衍生物的合成方法

以木犀草素为起始原料,通过与氯化苄发生选择性苄基化,再进行酰基化或烷基化反应,最后催化氢解得到系列 5-O-取代衍生物.该合成路线简便可行,适合木犀草素衍生物的合成.     

二丁基氧化锡在糖衍生物选择性合成中的应用

二丁基氧化锡和糖上的羟基选择性地形成亚甲锡烷基缩醛,通过聚合作用使处于聚合体不同位置的羟基显示了不同的电负性和亲核性,进行选择性反应合成糖衍生物.因此,利用二丁基氧化锡这种反应特性,分别对其在活性糖的保护、形成糖聚合体和糖基化等方面的应用进行了阐述,为该试剂在糖衍生物合成中的广泛应用提供参考.     

Behavior of chlorophyll derivatives in canola oil processing

Chlorophyll derivatives in canola oil were analyzed quantitatively by reversed-phase high-performance liquid chromatography without any pretreatment. The main components were pheophytin (pheo) a and b and pyropheophytin (pyro) a and b. The factors affecting the types and concentration of chlorophyll derivatives in oil have been investigated during seed preparation, expelling, extraction, degumming and alkali-refining processes. Bleaching tests of alkali-refined canola oil with activated earth indicated the adsorption of each derivative to decrease in the following order: pheo a > pyro a >> pheo b > pyro b. In bleaching with activated carbon, however, the following order was observed: pyro b > pheo b > pheo a > pyro a.     

A simple preparative procedure for the rapid isolation of phytosphingosine from the yeastHansenula ciferrii

Phytosphingosine and dihydrosphingosine were isolated as a mixture of their N-acetyl derivatives from the cells of the yeastHansenula ciferrii. After alkaline hydrolysis of the N-acetyl compounds, the free base mixture was reacted with either acetone orp-nitrobenzaldehyde. The reaction products consisting of the carbonyl derivative of phytosphingosine and free dihydrosphingosine were separated on an acetyl cellulose column. The acetone orp-nitrobenzaldehyde derivative of phytosphingosine recovered from the benzene eluate contained no dihydrosphingosine as determined by thin layer and gas liquid chromatography. The operating time from preparation of the derivative through column purification was less than 3 hrs. Mass spectrometry of the acetone andp-nitrobenzaldehyde derivatives disclosed in each case that ring closure with the carbonyl reagent involved the amino and primary hydroxyl groups to giveD-ribo-2-dimethyl-4-(2,3-dihydroxyhexadecyl) oxazolidine andD-ribo-2-p-nitrophenyl-4-(2,3-dihydroxyhexadecyl) oxazolidene, respectively.     

Glycosylated derivatives of steffimycin: insights into the role of the sugar moieties for the biological activity

Expression of the steffimycin gene cluster in Steptomyces albus in combination with plasmids directing the biosynthesis of different neutral and branched-chain deoxyhexoses led to the identification of twelve new glycosylated derivatives of steffimycin with different degrees of decoration in the tetracyclic core. These experiments demonstrate the flexibility of L-rhamnosyltransferase StfG for recognition of a variety of D- and L-deoxyhexoses, harboring different degrees of deoxygenation as 2-deoxyhexoses, 2,6-deoxyhexoses, and 2,3,6-deoxyhexoses, and their attachment to 8-demethoxy-10-deoxysteffimycinone. In addition, the flexibility of 3'-O-methyltransferase OleY, from Streptomyces, for the methylation of deoxyhexoses attached to the steffimycin aglycone is shown by expression of oleY in Streptomyces steffisburgensis, leading to the isolation of 3'-O-methylsteffimycin. Analysis of the biological activities of these compounds against three human tumor cell lines-breast adenocarcinoma, non-small cell lung cancer, and colon adenocarcinoma-revealed two of them, 3'-O-methylsteffimycin and D-digitoxosyl-8-demethoxy-10-deoxysteffimycinone, to possess improved antitumor activities, showing GI50 values below 1.0 microM, while steffimycin's GI50 values fluctuate between 2.61 to 6.79 microM depending upon the cell line used. The antitumor activity data provide some insights into the structure-activity relationships of the new steffimycin derivatives, in relation to the configuration of hydroxy groups at positions C-3' and C-4' of the sugar moiety and positions C-8 and C-10 of the tetracyclic core.     

Characterization of gangliosides of porcine erythrocyte membranes: Occurrence of ganglioside GD3 as major ganglioside

Four major ganglioside species were isolated from porcine erythrocyte membranes by DEAE-Sephadex and Iatrobeads column chromatography. Treatment of the lipids with graded neuraminidase and β-galactosidase, gas chromatographic analysis of their carboyhydrates, sphingosine bases and molecular species of sialic acid revealed that the structure of these gangliosides were G_M3(NeuAc), G_M3(NeuGc), G_D3(NeuAc) and G_D3(NeuGc), each of which was 16±2 μg, 304±42 μg, 30±3 μg and 240±26 μg, respectively, per gram of the dry erythrocyte stroma. The amount of G_M3 and G_D3 accounted for more than 95% of total gangliosides of the erythrocytes. Porcine erythrocytes may provide a good source for large scale preparation of ganglioside G_D3 which recently was identified as a human melanoma-associated antigen. Gangliosides are named according to Svennerholm (1) and the recommendation of the IUPAC-IUB Commission on Biochemical Nomenclature (2).     

Analysis of commercially available ganglioside standards

Procedures for the quantitative estimation of sialic acid, sphingosine and fatty acid were employed to assess the purity of commerically available ganglioside standards. Based on the weight printed on the label, experimental values of mono-, di- and trisialoganglioside standards represented approximately 7, 77 and 25%, respectively, of the expected value. Thin layer chromatography (TLC) revealed that the monosialoganglioside was contaminated with phospholipid, possibly phosphatidyl choline. Trisialoganglioside was resolved into three spots on TLC, two of which were ninhydrin positive and resorcinol negative. These results suggest that caution should be observed when dealing with commercially available standards even though a high degree of purity is guaranteed.     

A facile and effective procedure for the synthesis of 4-thiazolidinone derivatives using Y(OTf)3 as catalyst

A one-pot three-component reaction for the synthesis of 4-thiazolidinone derivatives has been established by reacting readily available and inexpensive starting materials of amines, aldehydes and thioglycolic acid using Y(OTf)₃ (5?mol%) as catalyst in tetrahydrofuran. This method is very efficient due to low catalyst loading and mild reaction conditions and provides an efficient and promising synthetic strategy for the construction of the thiazolidinone skeleton.     

糖醇氢解催化剂研究进展

催化剂研究是糖醇氢解体系的核心。综述糖醇催化氢解的催化剂研究进展,介绍贵金属催化剂、镍系催化剂、铜系催化剂、双金属催化剂以及其他催化剂在糖醇氢解反应中的应用,分析各类催化剂的优缺点,并对催化体系研究方向进行展望。     

多酶共固定化技术在糖类催化中的研究进展

糖类的催化反应对人体生命活动和工业生产具有重要意义。近年来,多酶共固定化技术迅速发展,为糖类的催化反应提供了一个绿色高效的研究工具。本文结合糖类催化中的多酶级联反应,系统阐述了多酶共固定化的方法,包括传统方法和新型方法,并指出了其各自的原理和优缺点。在此基础上,详细介绍了多酶共固定化技术在糖类催化中的应用,如淀粉的水解、纤维素的利用以及功能性糖的合成等,结果表明多酶共固定化技术不仅具有高效催化、稳定性强、易于分离等特性,而且能够充分发挥多酶之间协同催化的优势,极大地促进了糖类催化反应的进行。最后分析了多酶共固定化技术目前存在的问题与挑战,提出了一些解决问题的研究思路和方法,并展望了其发展前景。     

3,3′‐Diindolylmethane imprinted polymers: synthesis,characterization and analytical procedure for template isolation from biological matrix

A novel sorbent for the separation of 3,3′‐diindolylmethane (DIM) has been developed. DIM was used as a template molecule to prepare twelve imprinted polymers from seven different functional monomers in six various porogens in the presence of ethylene glycol dimethacrylate as a crosslinker. The binding capacity showed that the highest binding specificity was achieved when allylamine as the monomer and carbon tetrachloride as the porogen were used to form bulk polymers. Binding capacities were 130.4 ± 2.8 µg g^?1 for imprinted MIP7_a polymer versus 49.03 ± 0.44 µg g^?1 for non‐imprinted NIP7_a polymer. An imprinting factor of 3.12 reflected the high specificity of MIP7_a. A solid‐phase extraction protocol was fully optimized. Two methanol–water systems were selected as the most effective for loading and washing steps, while acetonitrile was chosen as the most efficient eluent suitable for recovery of 91.7 ± 3.8% of DIM. Optimal concentration of DIM and volume of loaded sample were also examined. A loaded volume of 2.5 mL was the most appropriate for 0.625 and 1.25 mg L^?1. The use of MIP7_a for the separations of DIM from spiked bovine serum albumin was evaluated, showing a total recovery of 87.7 ± 3.5%. The commercial sorbent C18 was not suitable for such an application. © 2013 Society of Chemical Industry