杂环生物碱类化合物的分离及结构鉴定

首次报道从中国南海西沙群岛海绵spongiaobligue中分离得到3个新的含氮生物碱杂环化合物,通过MS,1DNMR,20NMR等波谱数据及元素分析确定它们的结构。     

Isolation and identification of mutagenic nitro-pah in diesel-exhaust particulates

More than 50 nitro-PAH have been tentatively identified in an extract of diesel-exhaust particulates. Identifications are based on high-resolution mass spectrometry of directly mutagenic fractions derived from sequential fractionation of the extract by both low- and high-resolution liquid chromatography. The diversity of nitro-PAH tentatively identified suggests that large numbers of such compounds are formed during or following the combustion process.     

Flow-injection determination of creatine in animal tissues

After deproteination of samples with trichloroacetic acid, creatine is determined by reaction with 1-naphthol and biacetyl, based on a stopped-flow method. The calibration graph is linear over the range 0–250 mg l^?1, and recoveries from muscle samples are quantitative.     

Isolation and structural determination of spilacleosides A and B having a novel 1,3-dioxolan-4-one ring

As the first natural product incorporating 1,3-dioxolan-4-one in spiro structure, spilacleosides A and B were isolated from Ruscus aculeatus, and the absolute structures determined.     

Isolation and structural determination of xerophytolic acid A, a 3-geranyl-4-hydroxybenzoate derivative from Xerophyta plicata

A novel compound of a rare class of secondary metabolites, 3-geranyl-4-hydroxybenzoic acid derivative, methyl xerophytolate A (2), was isolated from the crude extract of Xerophyta plicata (Velloziaceae) collected in Rio de Janeiro, Brazil. The structure of 2 was elucidated using spectroscopic methods.     

Isolation and structural determination of vulgarone a and b,two novel sesquiterpene ketones from chrysanthemum vulgare

Two new sesquiterpene ketones, vulgarone A and B, were isolated from the essential oil of Chrysanthemum vulgare. The structures were determined based on comparison of the spectral properties with those of chrysanthenone and verbenone, and on the chemical interconversion.     

Amperometric biosensor for the determination of creatine

An amperometric biosensor for the determination of creatine was developed. The carbon rod electrode surface was coated with sarcosine oxidase (SOX) and creatine amidinohydrolase by cross-linking under glutaraldehyde vapour. The SOX from Arthrobacter sp. 1–1 N was purified and previously used for creation of a creatine biosensor. The natural SOX electron acceptor, oxygen, was replaced by an redox mediating system, which allowed amperometric detection of an analytical signal at +400-mV potential. The response time of the biosensor was less than 1 min. The biosensor showed a linear dependence of the signal vs. creatine concentration at physiological creatine concentration levels. The optimal pH in 0.1 M tris(hydroxymethyl)aminomethane (Tris)–HCl buffer was found to be at pH 8.0. The half-life of the biosensor was 8 days in 0.1 M Tris–HCl buffer (pH 8.0) at 20 °C. Principal scheme of consecutively followed catalytic reactions used to design a biosensor for the determination of creatine     

Isolation and structural characterization of a pectin homo and ramnogalacturonan

With a purpose to achieve an individual components of the pectins there was purified and separated the acidic components of the apple pectin and its chemical structure was studied using (13)C-NMR-Spectroscopy. The apple pectin was consecutively subjected to processing with hydrochloric acid and ethanol mixture, ultracentrifuging at 7000 and 40 000 rpm, ultrafiltration, fractionation on cellulose (DEAE-52) ion exchanger, eluting by the phosphate buffer. The contents of the acidic and neutral polysaccharides in an initial pectin and in the selected fractions controlled by narrow-band filter - spectroscopically in relation to E(q)=E(298)/E(315). In the (13)C-NMR-spectrums of the pectins before purifications on the ion exchanges besides the signals characteristic for homogalacturon, resonances are observed at 105.8, 79.01, 76.3, 73.9, 70.0 and 18.32 m.d., appropriate to the ramnogalacturonan residues. Resonance lines of acidic fraction in the field of 69.8, 70.6, 72.3, 80.6, 100.6 and 176.6 m.d. are referred to homogalacturonan residues and signals at 55.9, 73.3, 80.8, 101.6 and 172.6 m.d. to their methoxyl group. Minor resonance at 18.32 originated from C-6 rhamnose residues, substituted or unsubsituted with galactosyl-chains. Hence it has been shown that the apple pectin consist mainly of linear homogalacturonan and branched ramnogalacturonan macromolecules.     

Simultaneous determination of creatine and creatinine using amperometric biosensors

In order to determine creatine and creatinine amperometric biosensors were proposed. A bienzymatic biosensor based on creatinase (CI) and sarcosine oxidase (SO) was used for the assay of creatine and a trienzymatic biosensor based on CI, SO and creatininase (CA) for the assay of creatinine. The linear concentration ranges are of pmol l⁻¹ to nmol l⁻¹ magnitude order, with very low limits of detection. The biosensors proved high reliability for determination of creatine and creatinine as raw material, and in the pharmaceutical formulation.     

Spectrophotometric determination of a thiobarbituric acid-reactive substance in human hair.

A simple and sensitive spectrophotometric method for the determination of a thiobarbituric acid-reactive substance (TBARS) in human hair has been developed. The proposed method is based on the formation of a red-colored product by the reaction of products of lipid peroxidation with thiobarbituric acid in an acidic medium. The absorbance of the resulting red product was measured at 534 nm. The linear dynamic range was between 1.0 and 20 micromol/L. The recoveries were 98.3-105.0%, and the relative standard deviations (RSD) were 0.32-1.24, respectively. TBARS in digested hair sample was stable for 3 days at room temperature. It was found that, using this method, the hair TBARS concentration in smokers (0.116 +/- 0.030 micromol/g, n = 30) was significantly higher than that in non-smokers (0.096 +/- 0.015 micromol/g, n = 30) (p < 0.05).     

Isolation and structural clarification of chlamydocin

The constitution of Chlamydocin – a metabolite of Diheterospora chlamydosporia with pronounced cytostatic activity – is proposed on the basis of chemical reactions and physical data. The synthesis of a derivative of a new amino acid is described. The biological activities of this compound and of derivatives of Chlamydocin are discussed.     

Isolation and structural clarification of cryptosporin

The structure and absolute configuration of Cryptosporin ( 11 ), a metabolite of the fungus Cryptosporium pinicola LINDER has been elucidated.     

Isolation,structural determination and cytotoxic activity of two new ceramides from the root of Isatis indigotica

Two new ceramides were isolated from the 95% EtOH extract of traditional Chinese medicinal plant Isatis indigotica. Their structures were elucidated as 1-O-β-D-glucopyranosyl-(2S, 3R)-N-(2'-hydroxypentacosanoyl)-octadeca-11E-sphingenine (1) and 1-O-β-D-glucopyranosyl-(2S,3R)-N-(2'-hydroxyhe xacosanoyl)-octadeca-11E-sphingenine (2) on the basis of spectroscopic data. Their cytotoxic effects were evaluated by using MTT method.     

Isolation and structural characterisation of okara polysaccharides

Okara is a byproduct generated during tofu or soymilk production processes. Crude polysaccharide (yield 56.8%) was isolated by removing fat, protein and low molecular weight carbohydrates from initial okara. Crude okara polysaccharide was further divided into four soluble fractions and an insoluble residue fraction by extracting with 0.05 M EDTA + NH(4) oxalate, 0.05 M NaOH, 1 M NaOH and 4 M NaOH, with yields of 7.7%, 3.6%, 20.7%, 16.0% and 27.9%, respectively. Arabinose, galactose, galacturonic acid, xylose and glucose (only for the insoluble fraction) were the major constituent sugars. The primary sugar residues of okara polysaccharides were 1,4-linked β-galactopyranose, 1,5- and 1,3-linked α-arabinofuranose, 1,5-linked α-xylofuranose, 1,2-linked, 1,2,4-linked and terminal α-rhamnopyranose (or fucopyranose), and 1,4-linked β-glucopyranose (only for the insoluble fraction), indicating okara polysaccharides might contain galactan, arabinan, arabinogalactan, xylogalacturonan, rhamnogalacturonan, xylan, xyloglucan and cellulose.     

Isolation and structural elucidation of a new sildenafil analogue from a functional coffee

A sildenafil analogue was detected in a functional coffee sample labelled to have male sexual performance enhancement effects. This analogue was isolated and purified by flash chromatography and preparative high-performance liquid chromatography. Its structure was elucidated using high-resolution mass spectrometry; electrospray ionization-tandem mass spectrometry; and nuclear magnetic resonance spectroscopy, ultraviolet spectroscopy, and infrared spectroscopy. Compared with sildenafil, instead of an N-methylpiperazinyl moiety, ring opening of the piperazine ring with the loss of a carbon atom resulted in a substituted benzenesulfonamide. The chemical name of this analogue is N-[2-(dimethylamino)ethyl]-4-ethoxy-3-(1-methyl-7-oxo-3-propyl-6,7-dihydro-1H-pyrazolo[4,3-d]pyrimidin-5-yl)benzenesulfonamide. It is named descarbonsildenafil because it has one less carbon atom when compared with sildenafil.     

Bioluminescence flow sensor for determination of creatine kinase activity in blood

A bioluminescent flow sensor was developed for the assay of creatine kinase (CK) using firefly luciferase immobilized on a nylon coil. The CK-catalysed reaction of creatine phosphate with ADP took place in a cuvette before the injection into the bioluminescent detector coil. The response was linear from 0.1 to 100 U l^? at 25°C. An advantage of the flow sensor is a detection limit of less than 0.1 U l^?1, which, together with a high precision, allows determination of the CK activity in blood sera in about 5 min. The intra- and inter-assay reproducibilities (RSD) were less than 10% and the recovery range was 86–110%. The results agreed well with those obtained with a spectrophotometric method and with the normal reference values.