New Terpenoids And Lignans From The Twigs Of Tripterygium Hypoglaucum

Abstract

Six new compounds, including three terpenoids (1-3) and three lignans (4-6), were isolated from the 95% EtOH extract of the twigs of Tripterygium hypoglaucum. Their structures were determined on the basis of extensive spectroscopic analysis. 9′-O-benzoyl-lariciresinol (4) showed weak cytotoxicity against HepG2/Adr cells, with an IC₅₀ value of 30.1?μM in vitro.     

Note: Synthesis And Crystal Structure Of A Binuclear Fumarate Complexof Copper(II) With 1,10-Phenanthroline

As dicarboxylate complexes of transition metal possess potentially useful electronic and magnetic properties, [Mehrotra and Bohra (1983). Metal Carboxylates. Academic Press, London], much interest in their synthesis and structure has been apparent recently [Kaneko and Tsuchida (1981). J. Polymer Sci . , Macromolecular Reviews, 16, 397; Holton, Lappert, Pearce and Yarrow (1983). Chem. Reviews, 83, 135]. A series of metal complexes bridged by dicarboxylates has been synthesized in our laboratory and crystal structures show versatile coordination modes for the carboxyl group [Cheng, Liu, Xu and Xu (1999). J. Coord. Chem., 48 , 495; Nie, Liu, Luo and Xu (2001). J. Coord. Chem., 53, 365]. As a part of this investigation, we have synthesized a binuclear fumarate complex of Cu(II). X-ray analysis shows considerable coordination distortion resulting from close stacking interaction of aromatic phen rings.     

Comparison Of Highly Sensitive Sandwich Enzyme Immunoassay And Radioimmunoassay For Human Ferritin

Abstract

A highly sensitive sandwich enzyme immunoassay (EIA) for human ferritin was developed using rabbit anti-ferritin IgG-coated polystyrene balls and affinity-purified rabbit anti-ferritin Fab' labelled with β-D-galactosidase from Escherichia coli and compared with the corresponding sandwich radioimmuno assay (RIA). The specific and nonspecific binding of labelled anti-ferritin to the polystyrene balls were examined in relation to the amount of labelled anti-ferritin used per tube, and the highest sensitivity of each immunoassay (0.2 amol/tube in EIA and 2.5 amol/tube in RIA) was obtained by using the minimal amount of the corresponding labelled anti-ferritin (0.71 fmol in EIA and 4.5 fmol=4436 cpm in RIA) which gave a reliable calibration curve. The sandwich RIA was less sensitive, largely because the specific radioactivity of ¹²⁵I-labelled anti-ferritin used was not sufficiently high.     

Synthesis Of Isomaltose Analogues

ABSTRACT

Preparation of the α-glucosides 11, 12, 13 and 14 were accomplished through glycosylation of racemic trans-1-hydroxy-2-(hydroxymethyl)cyclohexane using 2-thiopyridyl tetra-O-benzyl-glucoside as the glycosyl donor in acceptable overall yield for α-selectivity, but with poor regioselectivity. Glycosylation under thermodynamic control using tetrabenzyl glucopyranose acetate and trimethylsilyl triflate as the promotor gave similar results. The unprotected glucosides 12 and 13 were separated and characterized by NMR spectroscopy. Similarly methyl 4-deoxy-α-isomaltoside (5a) was prepared through halide catalyzed glycosylation of methyl 2,3-di-O-benzoyl-4-deoxy-α-D-glucopyranoside (15) in acceptable yield and the unprotected compound characterized by NMR spectroscopy. Compounds 5a, 12a, 13a and the mixture 11a and 14a were all tested as substrates for the enzyme glucoamylase from Aspergillus niger and proved to be very poor substrates for the enzymic hydrolysis.     

Extraction And Spectrophotometric Determination Of Cadmium Based On The Formation Of A Ternary Complex With Cadion And 1, 10-Phenanthroline

Abstract

Cadmium ion reacts with cadion and 1, 10-phenanthroline to form a 1:1:2 orange-red ternary complex in 0.5N sodium hydroxide medium. The complex is extracted by chloroform and has a molar absorptivity of 9.2 × 10⁴ l. mole^?1. cm^?1 at 490 nm. A method is developed for the determination of cadmium in electroplating waste water.     

Synthesis Of Ligands Related To The O-Specific Antigen Of Shigella Dysenteriae Type 1.

Abstract

Stereoselective α-D-galactosylation at the position 3 of 4,6-O-substituted derivatives of methyl 2-acetamido-2-deoxy-α-D-glucopyranoside is described. Glycosyl chlorides derived from 3,4,6-tri-O-acetyl-2-O-benzyl- and 2-O-(4-methoxybenzyl)-D-galactopyranose have been used as glycosyl donors. Methyl 2-acetamido-4,6-di-O-acetyl-2-deoxy-3-O-(3,4,6-tri-O-acetyl-α-D-galactopyranosyl)-α-D-glucopyranoside (27) and methyl 2-acetamido-4,6-di-O-benzyl-2-deoxy-3-O-(3,4,6-tri-O-acetyl-α-D-galactopyranosyl)-α-D-glucopyranoside (31) have been prepared.     

Determination Of Mexacarbate And Five Of Its Derivatives By High-Performance Liquid Chromatography

Abstract

A simple, sensitive and reliable analytical method has been developed and reported for mexacarbate (4-ditnethylamino-3,5-xylyl N-methylcarbamate) and five of its possible degradation products likely to be found in environmental samples using reversed-phase high-performance liquid chromatography with isocratic and gradient solvent systems. All chromatogram peaks were Identified through comparison to standards. The method has been used to identify and separate the six compounds from a mixture of the standards. It has been evaluated under different column conditions and with different mobile phases. Best resolution of the analytes was obtained by using a gradient solvent system consisting of CH₃CN and H₃O detecting at 200 nm and 30°C using a HP-RP8, 10 μ m, 20 cm 4.6 mm column.     

Synthesis And Characterization Of Complexes Of Rare Earth Elements With 1,1-Cyclobutanedicarboxylic Acid

The complexes of yttrium and lanthanide with 1,1-cyclobutanedicarboxylic acid of the formula: Ln₂(C₆H₆O₄)₃⋅nH₂O, where n=4 for Y, Pr–Tm, n=5 for Yb,Lu, n=7 for La, Ce have been studied. The solid complexes have colours typical of Ln³⁺ ions. During heating in air they lose water molecules and then decompose to the oxides, directly (Y, Ce, Tm, Yb) or with intermediate formation. The thermal decomposition is connected with released water (313–353 K), carbon dioxide, hydrocarbons(538–598 K) and carbon oxide for Ho and Lu. When heated in nitrogen they dehydrate to form anhydrous salt and next decompose to the mixture of carbon and oxides of respective metals. IR spectra of the prepared complexes suggest that the carboxylate groups are bidentate chelating. This revised version was published online in August 2006 with corrections to the Cover Date.     

State Of The Art For The Examination Of Uv Spectra Of Waters And Wastewaters

Abstract

The paper reviews different mathematical methods for the exploitation of the UV spectrum of waters and wastewaters, including the interferences treatment. After the presentation of simple methods and their limits, several global approaches using a matricial presentation of the data are discussed. The usual methods, statistical multivariate or deterministical procedures are not relevant. Nevertheless, other methods based on the restitution of interferences effect as a combination of fixed basic signals, either mathematical or physical, are available. The first procedure is semi-deterministic without chemical knowledge of the interferences nature or effects-and only mathematical hypothesis on the spectrum shape-while the second is a more qualitative method based on the fact that most of interferences can be resumed as a linear combination of few independent spectra with chemical signification. These considerations underline the importance of direct examination of UV spectra of waters and wastewaters.     

Detection Of Amines With Dichloroacetaldehyde And Chloral-Dichoroacetaldehyde Copolymer

Abstract

Methods are described for the detection of amines as vapors and in solution. The lower limit of detection of diethylamine or triethylamine vapors by drawing the vapor through a detector tube containing silica gel impregnated with dichloroacetaldehyde and then heating is 25 μg. As low as 1 μg of the same amines can be detected In aqueous solution by the degradation of a chloral-dichloroacetaldehyde copolymer. Detection signal in the latter case is the appearance of fluorescence when liberated monomer dissolves a 2-diphenylacetyl-1,3-indandione derivative.     

Hptlc Separation And Determination Of Amniotic Fluid Phospholipids

Abstract

High performance thin layer chromatography (HPTLC) under controlled relative humidity conditions was employed in order to separate phospholipids of amniotic fluid. Quantitative determination was accomplished after visualization by copper acetate/phosphoric acid (CA) and by phospho-molybdic acid (PMA). In both cases reflectance was found to follow the Kubelka-Munk theory in the Treiber and Pollak approximation. PMA gives fairly better results as it concerns reproducibility. A method of analysis is proposed that allows to use 500 μl or less of amniotic fluid. A complete phospholipid analysis can be performed in 40 min. Proposed method was tested on simulated and real samples and results compared with conventional spectrophotometry analysis.     

Stability-Indicating Method For The Determination Of N-Desmethyldiazepam And Simultaneous Determination Of Its Degradation Products

Abstract

A simple, direct and sensitive spectrophotometric method for the determination of the intact N-desmethyldiazepam in the presence of its degradation products, 2-amino-5-chlorobenzophenone and glycine, is developed. The proposed procedure is based on direct measurement of the absorbance of its acidified methanolic solution at 361 nm. The procedure determines 8–56 mcg ml^?1 of N-desmethyldiazepam with an accuracy of 100.2 ± 0.51%. The proposed procedure retains its accuracy in presence of up to 80% of the different degradation products. The procedure is applied successfully for the determination of N-desmethyldiazepam in bulk powder, tablets and drops.

Simultaneous determination of the different degradation products in the presence of the parent drug is also described. Thus, 2-amino-5-chlorobenzophenone is determined by direct measurement of its methanolic solution at about 380 nm, with an accuracy of 100.4 ± 0.42%. Glycine is determined colorimetrically using ninhydrin reagent in presence of pyridine, with an accuracy of 99.5 ± 0.78%.     

Photooxidation Of Arsenobetaine And Arsenocholine To Generate Arsines Previous To Icp-Oes Measurement

Abstract

A photolytic method, which uses UV irradiation (254 nm) and K₂S₂O₈ in alkaline media has been optimized for the speciation of arsenite, arsenate, monomethylarsonic and dimethylarsinic acid, arsenobetaine and arsenocholine. Under these conditions it is possible to obtain not only simple species from arsenobetaine and arsenocholine with good yields, but also to establish the optimum conditions to carry out the process on-line with HG-ICP/OES for the determination of these species.

The products obtained in the photolytic reaction are introduced into the reduction chamber to form arsines. According to the results obtained from the ICP measurements, the recoveries obtained are about 100% and the procedure has a good reproducibility.     

Time-Resolved Spark-Source Mass Spectrometry; The Effect Of Spark Duration On Ion Intensity And Precision Of Analysis

Abstract

A radio-frequency probe and a synchronized electronic ion-beam chapper have been used to determine ion-intensity variation with spark duration. Large peaks in multiply charged ion intensities are detected in the early stages of the radio-frequency spark, while later in the spark period the singly charged species predominate. The effects of these variations on the precision of analysis have been determined. A gate was selected in the spark pulse, and a factor of two increase in precision was obtained.     

Determination Of Chlorpromazine And Its Sulfoxide And 7-Hydroxy Metabolites By Ion-Pair High Pressure Liquid Chromatography

Abstract

An ion-pair HPLC approach with ordinary silica has been applied, with detection by ultraviolet absorption, to the assay of plasma for chlorpromazine and its sulfoxide on the one hand, and for 7-hydroxychlorpromazine (an active metabolite) on the other hand. The respective sample-preparation procedures entail extraction of the plasma with heptane at strongly alkaline pH, or else with diethyl ether at a less alkaline pH and with ensuing back-extraction and re-extraction. For each of the compounds, levels as low as 10 ng. ml^?1 are measurable. The conditions adopted are such that specificity and reproducibility are satisfactory although chlorpromazine and its various metabolites, especially 7-hydroxychlorpromazine, are chemically unstable and, moreover, are readily lost onto glass. With the unorthodox separation system adopted, adsorption rather than partition appears to be the dominant mechanism.     

A Comparison Between Chemical Ionization And Electron Impact Techniques Of Mass Spectrometry For The Estimation Of N-Nitrosodimethylamine

Abstract

Some beverage and meat products are examined for the presence of N-nitrosodimethylamine by both Low- and High- Resolution Chemical Ionization Mass Spectrometry, compared with that by Electron Impact method to assess their reliability. All the data obtained from these MS methods have been treated by Statistical analysis, and the result obtained shows that the variances are not significant between each other, but the Low- Resolution Electron Impact MS with single ion monitoring gives rise to inconsistency among them.     

Rapid Determination Of Total Sulfur In Plants And Soils By Combustion Sulfur Analysis

Abstract

An automatic sulfur titrator paired with a high-frequency induction furnace were used to determine total sulfur concentrations in Alaska soil and plant material. Results were in close agreement with those obtained by turbidimetric and gravimetric methods and by similar combustion methods.     

Molecular Mechanisms Of Sweet Taste 2: Glucopyranose,Fructopyranose And Sucrose

Abstract

Interactions of glucopyranose, fructopyranose and sucrose with a proteinaceous receptor model have been examined to validate the stereomolecular mechanisms of sweet taste proposed for sugars. The methylene groups at C-6 of glucose, at C-1 and C-6 of fructose and at C-6, C-1' and C-6' of sucrose appear to play an important role as dispersive interaction centres with the receptor.     

A Simple Microdetermination Of Polymer Flocculants (Polyacrylamides And Guar) In Mine Water

Abstract

An extremely simple, sensitive and selective microdetermination of polymer flocculants in mine water is feasible by measuring the laminar flow rate through membrane filter under vacuum.     

Novel Reaction Route Including Enzymic Reaction For A Synthesis Of A Branched Polysaccharide

Abstract

Stereoselective synthesis of α-D-glucosyl-branching polysaccharide by chemical and enzymic reactions was investigated. Ring-opening polymerization of 1,6-anhydro-3-O-benzoyl-2,4-di-O-benzyl-β-D-glucopyranose (1) with PF₅ as catalyst at low temperature gave a highly stereoregular polymer, which was converted to 2,4-diO-benzyl-(1→6)-α-D-glucopyranan by debenzoylation with sodium methoxide. The polymer was glucosylated according to the glycosyl imidate method. Deprotection of the branched polysaccharide was carried out with sodium in liquid ammonia at -78 °C to give a (1→6)-α-D-glucopyranan having α-D-glucopyranosyl and β-D-glucopyranosyl branches. Only the β-D-glucopyranosyl branch of the polymer was completely removed by enzymatic hydrolysis by the use of cellulase to provide stereoregular (1→6)-α-D-glucopyranan having an α-D-glucopyranosyl branch at the C-3 position. Polymers were characterized by optical rotation, NMR spectroscopy, GPC, and X-ray diffractometry.