Echiofruzine, a novel naringenin diglycoside from Echiochilon fruticosum growing in Tunisia

The aerial parts of the Tunisian plant Echiochilon fruticosum yielded a novel flavonol diglycoside: naringenin-5-O-beta-D-glycopyranoside-3-O-alpha-L-rhamnopyranoside, named Echiofruzine (1), together with the known compounds vomifoliol-9-O-beta-D-glucopyraroside (2), 1-oxo-alpha-ionyl-9-O-beta-D-glucopyranoside (3) and 1-O-[beta-D-xylopyranosyl(1 --> 6)-beta-D-glucopyranosyl] eugenol (4), described for the first time in the indicated plant. The structures of the four isolated compounds were established on the basis of chemical and spectroscopic evidence.     

Phytochemical investigation and biological studies of Bombax malabaricum flowers

In this study, extracts of the flowers of the folk medicinal plant Bombax malabaricum DC were biologically and chemically screened. Chemical constituents in the n-hexane fraction from the flowers of B. malabaricum DC were investigated using gas-liquid chromatography (GLC) analysis, affording 14 compounds, including cholesterol, stigmasterol, campesterol and α-amyrin, while the residual 10 compounds are hydrocarbons. GLC analysis of the fatty acid (FA) esters established the majority abundance of the saturated FA over their unsaturated analogues. The polar methanol fraction afforded seven flavones: vicenin 2 (1), linarin (2), saponarin (3), cosmetin (4), isovitexin (5), xanthomicrol (6) and apigenin (7). Structures 1-7 were established by intensive studies of various spectral data (H-NMR, mass spectroscopy and UV) and comparison with authentic samples. Compounds 1-7 are described here for the first time from this plant. Extracts of n-hexane and methanol exhibited significant antioxidant and antimicrobial activities.     

Flow injection spectrophotometric determination of boron in plant material with azomethine-H

A simple, fast method for the determination of boron in plant extracts is described. The method utilizes injection of 1.0 ml of an acid plant digest into a 0.1 M hydrochloric acid stream, with further addition of a buffer—masking solution and azomethine-H as the colour-forming reagent. Effects of pH, kinetics of colour reaction development, sample volume, reagent composition and interferences are described. The proposed method allows the analysis of plant extracts with boron contents in the range 0.1–6.0 ppm at a rate of 60 determinations per hour, with a reagent consumption of 2 mg of azomethine-H per sample. The precision is good (r.s.d. < 1%) and the results agree with those obtained by the curcumin method.     

Simultaneous Determination of Nickel and cobalt in Manganese Sulphate Electrolyte by DMGH2-Sensitized Differential Pulse Polarography

Abstract

A method is described for the simultaneous determination of nickel and cobalt in manganese sulphate electrolyte by the dimethylglyoxime (DMGH₂) sensitized differential pulse polarography. The high manganese sulphate background (1.2M) in the concentrated process plant electrolyte interferes only with the nickel determination and precludes its direct determination. A 50% v/v dilution and an excessive amount (2 × 10^?3M) of the chelating agent are required at pH7.7 for the reliable determination of both elements. Under these conditions, the linear concentration ranges are 0-110 μg/1 for nickel and 0-140 μg/1 for cobalt. The minimum detectable amounts above the levels present in the process plant electrolyte are 2 μg/1 and 1 μg/1 for both elements, respectively. The relative standard deviations for all measurements are between 1 and 3%.     

On-line monitoring with an ion-selective electrode in a high-volume flow-through cell

A high-capacity poly(vinyl chloride) flow-through cell which can be used at a flow rate of 3000 ml min^-1 in a corrosive environment is described for the continuous on-line monitoring of copper ions in plant electrolytes. The copper(II) ion-selective electrode and double-junction reference electrode in the cell are coupled to a voltmeter and microprocessor-controlled instrumentation to achieve on-line monitoring. The system is designed to withstand the severe industrial environments and was field-tested in a copper refinery where continuous monitoring of copper is required. Cell design and results of the investigation on the determination of copper in plant electrolytes are described.     

Spectrophotometric determination of uranium in process streams of a uranium extraction plant

This paper deals with the development and standardization of procedures for the determination of uranium on a routine basis in various process streams of a uranium extraction plant, covering a wide range of concentrations from 350 g 1(-1) down to 5 mg 1(-1) using only a spectrophotometric technique. The self-absorption of uranyl ion in dilute phosphoric acid and the violet-blue colour of the UO(2)(2+)-Arsenazo III complex in 4 M HC1 were exploited for high and low concentrations of uranium, respectively. The methods described were applied to samples of varying nature such as aqueous, organics and solids, involve minimal sample preparation and do not require prior separation of uranium from impurities. The interfering impurities in different process streams were also studied. Large quantities of silica as undissolved material poses a serious interference in the case of UNS and UNF. Considerable quantities of iron in UNS, UNF, UNR and UNRC cause interference. Possible remedies in these cases are suggested. Problems with the direct spectrophotometric measurement of organic samples is discussed. The effect of the presence of large quantities of ammonium nitrate and sodium nitrate in WD samples on the determination of uranium is also discussed. The results are compared with those obtained by volumetry and X-ray fluorescence spectrometry for higher concentrations of uranium and by extraction-spectrophotometry (ethyl acetate-thiocyanate method) for lower concentrations. Relative standard deviation of 1% and 5% for high and low concentrations, respectively, were obtained, which are adequate as far as process stream samples are concerned. The compared results are in fair agreement. The problems associated with the determination of uranium in these process streams are discussed. Experimental results for 10 different process streams normally encountered in a uranium extraction plant are tabulated.     

Plant‐like cadinane sesquiterpenes from an actinobacterial mangrove endophyte

Cadinanes are typical plant sesquiterpenes with a broad range of biological functions. We report the isolation of three cadinanes ( 1–3 ) from a bacterial endophyte (Streptomyces sp.) of the mangrove plant Bruguiera gymnorrhiza. The structures of two new cadinenes, (+)‐11‐hydroxy‐epicubenol ( 1 ) and (+)‐12‐hydroxy‐epicubenol ( 2 ) were elucidated by nuclear magnetic resonance (NMR) and mass spectrometry. The bacterial product (+)‐11‐hydroxy‐epicubenol was elucidated to be an enantiomer of the plant product pubinernoid C. (+)‐12‐Hydroxy‐epicubenol was established as a diastereomer of the basidiomycete product trichapargin A. In addition, a crystal structure analysis corroborated the structure and configuration of 5,11‐epoxy‐10‐cadinanol ( 3 ), a cadinane cycloether initially described as a natural product from liverwort. The discovery of oxygenated cadinanes from a bacterial endophyte may set the basis for the production of cadinanes by bacterial fermentation.     

A facile spectrophotometric method for the determination of selenium.

A rapid and sensitive spectrophotometric method is described for the determination of trace amounts of selenium using Variamine Blue (VB) as a chromogenic reagent. The proposed method is based on the reaction of selenium with potassium iodide in an acidic medium to liberate iodine, which oxidizes Variamine Blue to form a violet-colored species having an absorption maximum at 546 nm. Beer's law is obeyed in the range 2-20 g of selenium in a final volume of 10 ml. The molar absorptivity and Sandell's sensitivity were found to be 2.6 x 10(4) l mol-1 cm-1 and 0.003 microgram cm-2, respectively. The optimum reaction conditions and other analytical parameters were evaluated. The effect of interfering ions on the determination is described. The proposed method has been successfully applied to the determination of selenium in real samples of water, soil, plant materials, human hair, and synthetic samples of cosmetics and pharmaceutical preparations.     

Sesquiterpene lactones-based classification of the family asteraceae using neural networks and k-nearest neighbors

In a recent publication we described the application of an unsupervised learning method using self-organizing maps to the separation of three tribes and seven subtribes of the plant family Asteraceae based on a set of sesquiterpene lactones (STLs) isolated from individual species. In the present work, two different structure representations--atom counts (2D) and radial distribution function (RDF) (3D)--and two supervised classification methods--counterpropagation neural networks and k-nearest neighbors (k-NN)--were used to predict the tribe in which a given STL occurs. The data set was extended from 144 to 921 STLs, and the Asteraceae tribes were augmented from three to seven. The k-NN classifier with k = 1 showed the best performance, while the RDF code outperformed the atom counts. The quality of the obtained model was assessed with two test sets, which exemplified two possible applications: (1) finding a plant source for a desired compound and (2) based on a plant species chemical profile (STLs): (a) study the relationship between the current taxonomic classification and plant's chemistry and (b) assign a species to a tribe by majority vote. In addition, the problem of defining the applicability domain of the models was assessed by means of two different approaches-principal component analysis combined with Hotelling T2 statistic and an a posteriori probability-based rule.     

红外光谱法测定尿素生产中脱氢催化剂的 S(Ⅵ)含量

本文介绍一个用红外光谱法测定尿素生产装置内使用过的脱氢催化剂中S(Ⅵ)的含量(以SO_4~-形式存在)。取Al_2(SO_4)_3作标样,溴化钾压片法制备13mm样片,用补偿法测定1120cm~(-1)SO_4~(2-)吸收峰的光密度,绘制A_(1120)～S(Ⅵ)标准曲线。样片中SO_4~(2-)含量在1mg以内符合朗伯—比尔定律。当脱氢催化剂中S(Ⅵ)含量在20％以内,方法准确度为3％,平均偏差最大为0.20。文中并介绍了操作误差的来源及克服办法。     

A practical and improved synthesis of (3S,5S)-3-[(tert-butyloxycarbonyl)methyl]- 5-[(methanesulfonyloxy)methyl]-2- pyrrolidinone

A practical and improved synthesis of (3S,5S)-3-[(tert-butyloxycarbonyl)methyl]-5-[(methanesulfonyloxy)methyl]-2-pyrrolidinone (1) is described. The key transformations involve a highly efficient reaction sequence consisting of ethoxycarbonylation, alkylation, hydrolysis, and decarboxylation to produce compound 10. The process described herein is practical, robust, and cost-effective, and it has been successfully implemented in a pilot plant to produce a multikilogram quantity of mesylate 1.     

The Occurrence and Biological Activity of Tormentic Acid—A Review

This review focuses on the natural sources and pharmacological activity of tormentic acid (TA; 2α,3β,19α-trihydroxyurs-2-en-28-oic acid). The current knowledge of its occurrence in various plant species and families is summarized. Biological activity (e.g., anti-inflammatory, antidiabetic, antihyperlipidemic, hepatoprotective, cardioprotective, neuroprotective, anti-cancer, anti-osteoarthritic, antinociceptive, antioxidative, anti-melanogenic, cytotoxic, antimicrobial, and antiparasitic) confirmed in in vitro and in vivo studies is compiled and described. Biochemical mechanisms affected by TA are indicated. Moreover, issues related to the biotechnological methods of production, effective eluents, and TA derivatives are presented.     

Determination limits in high-performance liquid chromatography of plant phenolic compounds with an ultraviolet detector

The capabilities of high-performance liquid chromatography (h.p.l.c.) for the determination of phenolic compounds in 80% ethanol extracts from plant material are described. A reversed-phase column was used and elution was done with a linear gradient from 0.01 M phosphoric acid up to methanol. The efficiency of the method was studied via determination limits, defined as the minimum concentration of a compound (μg of compound per gram of extracted dry plant material) necessary to provide 90% probability that the relative error on the determination of the compound in an extract from a plant sample taken at random is < 10%. These limits take into account matrix interferences as a source of error, and were calculated with a minicomputer for the determination of 19 phenolic compounds in plant extracts. For good determinations, the concentrations of the components should be in the range 1–10 mg g^?1 of dry plant material. Separating the extracts into different chemical groups (on ion-exchange materials) prior to h.p.l.c. decreases the determination limits about five times. The dependence of determination limits on the u.v. characteristics of the compound, the sample clean-up, and the column characteristics are discussed quantitatively by means of a simple empirical equation.     

Acid digestion of geological and environmental samples using open-vessel focused microwave digestion

The application of open vessel focused microwave acid digestion is described for the preparation of geological and environmental samples for analysis using inductively coupled plasma-mass spectrometry (ICP-MS). The method is compared to conventional closed-vessel high pressure methods which are limited in the use of HF to break down silicates. Open-vessel acid digestion more conveniently enables the use of HF to remove Si from geological and plant samples as volatile SiF4, as well as evaporation-to-dryness and sequential acid addition during the procedure. Rock reference materials (G-2 granite, MRG-1 gabbros, SY-2 syenite, JA-1 andesite, and JB-2 and SRM-688 basalts) and plant reference materials (BCR and IAEA lichens, peach leaves, apple leaves, Durham wheat flour, and pine needles) were digested with results comparable to conventional hotplate digestion. The microwave digestion method gave poor results for granitic samples containing refractory minerals, however fusion was the preferred method of preparation for these samples. Sample preparation time was reduced from several days, using conventional hotplate digestion method, to one hour per sample using our microwave method.     

取代吡唑啉衍生物的合成与生物活性

采用α-三唑-β-烷氧基芳酮与肼关环,制备了1,3-二苯基-4-三唑基吡唑啉1a,1-苯基-3-对氯苯基-4-三唑基吡唑啉1b和3-取代苯基-4-三唑基吡唑啉(7),并研究了化合物7的成环优化条件.使用α,β-不饱和酮与肼关环合成了1,3,4,5-多取代吡唑啉衍生物1c-1h,并初步用质谱法确定了该反应产物的结构;同时,以3,5-二取代吡唑啉(6)和7作为中间体合成了1-,3-,4-或5-取代的化合物2a-2l.初步生物活性测定结果表明,所合成的化合物均有一定的杀菌、激素和除草效果.     

Determination of jasmonic acid in bark extracts from <Emphasis Type="Italic">Hevea brasiliensis</Emphasis> by capillary electrophoresis with laser-induced fluorescence detection

A simple and sensitive method is described for determination of jasmonic acid (JA) in plant tissues. The method is based on derivatization of JA with 5-bromomethylfluorescein (5-BMF) and separation and quantification of the resulting 5-BMF–JA derivative by capillary electrophoresis coupled to laser-induced fluorescence detection (CE–LIF). The derivatization conditions were studied in detail. Our results indicated that 5-BMF-labeled JA could be well separated from other plant hormones present in the sample by use of 20 mmol L^–1 borate buffer (pH 8.5). The response to JA was a linear function of concentration in the range 1 to 100 mol L^–1, with a correlation of 0.9986. Our preliminary work showed that the proposed method had fairly good selectivity and sensitivity. Only small amounts of plant sample are needed to complete the analysis. This described method enables the analysis of JA in crude extracts without extra purification and enrichment procedures.     

Determination of rhenium in plant materials

Methods for rhenium extraction from plant materials were studied using model systems and the ¹⁸⁶Re isotope. Conditions are described for the quantitative extraction of rhenium with acid and alkali solutions from plant ash and with ethanol and salt solutions from fresh green matter. Procedures for the analysis of real plant materials based on a combination of rhenium extraction with high-sensitive methods of its determination (catalytic, neutron activation, and solid-phase spectroscopy) were developed. Laboratory and field versions of the method are proposed. Analytical results for plant samples taken in different regions are presented.Translated from Zhurnal Analiticheskoi Khimii, Vol. 60, No. 1, 2005, pp. 97–103.Original Russian Text Copyright © 2005 by Borisova, Demin, Gatinskaya, Ermakov, Ryabukhin, Bozhkov.     

In silico analyses of a new group of fungal and plant RecQ4-homologous proteins

Bacterial and eukaryotic RecQ helicases comprise a family of homologous proteins necessary for maintaining genomic integrity during the cell cycle and DNA repair. There is one known bacterial RecQ helicase, and five eukaryotic RecQ helicases that have been described: RecQ1p, RecQ4p, RecQ5p, Bloom, and Werner. While the biochemical functions of Bloom and Werner helicases are well understood, the same is not true for RecQ4p helicase. RecQ4p mutations lead to pathologies like Rothmund-Thompson syndrome (RTS), RAPADILINO, and Baller-Gerold syndrome (BGS). Until now, RecQ4p helicases had only been described in metazoans, and their presence in organisms like fungi and plants were not known. Thus far only one RecQ-homologous protein (Sgs1p), similar to Bloom helicase, has been described in fungal genomes. In the present study we employed an in silico approach, and successfully identified and characterized a second RecQ helicase from the genomes of different fungal and two plant species that shows similarity to metazoan RecQ4 proteins. An in-depth phylogenetic analysis of these new fungal and plant RecQ4-like sequences (termed Hrq1p) indicated that they are orthologous to the metazoan RecQ4p. We employed hydrophobic cluster analysis (HCA) and three-dimensional modeling of selected Hrq1p sequences to compare conserved regions among Hrq1p, human RecQ4p and bacterial RecQp. The results indicated that Hrq1p sequences, as previously observed for metazoan RecQ4 proteins, probably act in genomic maintenance and/or chromatin remodeling in fungal and plant cells.     

(Z)-5-Tetradecen-14-olide,a New Macrocyclic Lactone,and Two Unsaturated Straight Chain Acetates from Ambrette Seed Absolute

(Z)-5-Tetradecen-14-olide ( 1 ), (Z)-5-dodecenyl acetate ( 2 ), and (Z)-5-tetradecenyl acetate ( 3 ) have been isolated from the absolute oil of Hibiscus abelmoschus L . The lactone 1 is a new macrocyclic musk compound, and the occurrence of the two acetates 2 and 3 in a plant is reported for the first time. Syntheses of the three compounds are described.     

Three New Isoflavonoids from the Aerial Parts of Ammopiptanthus mongolicus

Three new isoflavonoids, namely (±)‐ammopiptanine A ( 1 ), ammopiptanine B ( 2 ), ammopiptanoside A ( 3 ), together with 13 known compounds, were isolated from the aerial parts of Ammopiptanthus mongolicus. Their structures were elucidated on the basis of detailed spectroscopic analyses and by comparison with those of related model compounds. The isoflavonoids described, except formononetin, wistin, daidzein, and calycosin, were isolated from this plant for the first time.