bluuebunny/crossref_metadata_2025_split huggingface dataset:
Computer‐assisted elucidation of structures of natural products
Authors: Massiot G. , Nuzillard J. M. 
Published: March 2007

AbstractAn historical survey of the first computer programs capable of handling spectroscopic data and of transforming them into possible molecular structures is exemplified by some applications. Technological improvements of nuclear magnetic resonance spectroscopy now allow the direct collection of connectivity relationships between atoms, and the integration of this new kind of spectroscopic data by “intelligent” computer programs is demonstrated by the resolution of practical problems for which human expertise would not be straightforward.
Intermolecular aromatic acid association of an anthocyanin (petanin) evidenced by two‐dimensional nuclear overhauser enhancement nuclear magnetic resonance experiments and distance geometry calculations
Authors: Nerdal Willy , Andersen Øyvind M. 
Published: March 2007

AbstractA new mechanism is described for intermolecular association of the aromatic acid of the anthocyanin petanin (petunidin 3‐O‐[6‐O‐(4‐O‐E‐p‐coumaroyl‐α‐L‐rhamnopyranosyl)‐β‐D‐glucopyranoside]‐5‐0‐β‐D‐glucopyrano‐side) in cold solution. Petanin was studied in acidified methanolic solution using the nuclear Overhauser enhancement (NOESY) nuclear magnetic resonance technique at −5° and –20°C. Inter‐ and intra‐molecular coumaroyl group NOESY cross‐peaks were observed, and the corresponding proton‐proton distance bounds were used in distance geometry calculations to determine the association of the coumaroyl groups. The orientation of two associated petanin coumaroyl groups was found to be head‐to‐tail along the long coumaroyl group axis. The corresponding orientation along the short coumaroyl group axis could not be determined conclusively; however, the most probable orientation is head‐to‐head. Lack of observed NOESY cross‐peaks between protons of the coumaroyl group and the aglycone indicated absence of the intramolecular coumaroyl group‐aglycone association which has been suggested for other acylated anthocyanins. A structure for a petanin dimer is suggested.
Characterization of honeysuckle (Lonicéra caprifolium L.) seed oil triacylglycerols by high performance liquid chromatography and light scattering detection
Authors: Bergqvist Magnus H. J. , Olsson N. Urban 
Published: March 2007

AbstractA method is described which utilizes solvent extraction and preparative thin layer chromatography to isolate triacylglycerols from the seeds of the Genuine Honeysuckle (Lonicéra caprifolium L.). Preparative liquid chromatography in conjunction with gas chromatography and high performance liquid chromatography with light‐scattering detection were further used to characterize the pattern of molecular species of the triacylglycerols.
High performance liquid chromatography of zanhic acid glycoside in alfalfa (Medicago sativa)
Authors: Nowacka J. , Oleszek W. 
Published: March 2007

AbstractThe aerial parts of alfalfa (Medicago sativa L.) contain a considerable amount of zanhic acid tridesmoside which, due to its low activity, cannot be determined using standard biological procedures. A high performance liquid chromatographic method has been developed for its determination. The procedure employs the alkaline hydrolysis of the tridesmoside followed by the derivatization of released prosapogenins with 4‐bromophenacyl bromide. It is demonstrated that alkaline hydrolysis of tridesmoside generates different prosapogenins depending on the solvent used. The conditions for alkaline hydrolysis has been optimised.
A comparative study of two spectrophotometric methods for measuring coniferyl alcohol oxidation catalysed by peroxidase
Authors: Calderón A. A. , Munoz R. , Morales M. , Barceló A. Ros 
Published: March 2007

AbstractTwo spectrophotometric methods for measuring coniferyl alcohol (CA) oxidation catalysed by peroxidases are compared on the basis of their sensitivity, detection limit and validity for kinetic purposes. Measurement of the absorbance changes in the UV region (260 nm) is much better than evaluation in the visible range (620 nm), since the UV changes monitor the disappearance of CA in reaction media, while the VIS changes measure the appearance of lignin‐like products, which may not be kinetically correlated with CA oxidation. In addition, UV measurements are more sensitive and their detection limit is lower.
The determination of catecholamines in Crataegus oxyacantha L. Flowers and leaves by high pressure liquid chromatography‐electrochemical detection
Authors: Saija A. , Germano M. P. , Marzullo D. , Imperatore C. , Campo S. , De Pasquale R. 
Published: March 2007

AbstractA combined extraction system for the selective and quantitative determination of the monoamines noradrenaline, adrenaline, dopamine and L‐DOPA from the flowers and leaves of Crataegus oxyacantha L. has been developed. The method is based on a preliminary isolation of monoamines by successive petroleum ether and chloroform clean‐up, absorption on alumina and passage through Sep‐Pak C18 cartridges, followed by measurement of the catecholamines by high pressure liquid chromatography, with electrochemical detection, on a reversed phase column. The described method appears sufficiently simple, sensitive, precise and accurate for routine use and holds great promise for pharmacognostic studies.
Normal phase liquid chromatographic analysis of toxic norditerpenoid alkaloids
Authors: Manners Gary D. , Pfister James A. 
Published: March 2007

AbstractA normal phase, isocratic, analytical high performance liquid chromatographic (HPLC) method has been developed for the analysis of toxic methylsuccinimidoanthranoyllycoctonine (MSAL) norditerpenoid alkaloids occurring in poisonous larkspurs (Delphinium sp.). The method has good sensitivity, specificity for MSAL norditerpenoid alkaloid and rapid analysis times. The technique employs 5 μm neutral alumina as the stationary phase and utilizes a mixture of hexane: 95% isopropyl alcohol as the mobile phase. Accurate and reproducible analyses can be performed on 1 g samples of plant material. The method has been applied to the analysis of the chemical phenology of the MSAL norditerpenoid alkaloids methyllycaconitine and 14‐deacetylnudicauline in three species of tall larkspurs (Delphinium barbeyi, D. occidentale, D. glaucescens). Analytical results confirm the primary occurrence of these toxic alkaloids in early vegetative tissues of these plants, their concentration in reproductive plant tissues and their reduction in level with plant maturation. The chemical phenology results further confirm the observed difference in the toxicity of the three tall larkspurs (D. barbeyi > D. glaucescens > D. occidentale) to livestock. Intraspecies differences of toxic alkaloid occurrence associated with site were also demonstrated.
Annonaceous acetogenins: An updated review
Authors: Fang Xin‐Ping , Rieser Matthew J. , Gu Zhe‐Ming , Zhao Geng‐Xian , McLaughlin Jerry L. 
Published: March 2007

AbstractThe Annonaceous acetogenins are an exciting new class of bioactive natural products whose antitumour, pesticidal and other bioactivities are due to inhibition of electron transport in mitochondria. This paper tabulates the 61 compounds in this class which have been published in the period of 1990–1992 and reviews recent progress with the chemistry and biology of these potent compounds. (Appendices will be published in the next issue.)
Microassay to measure phytoalexin response in protoplasts of bean leaves
Authors: Soriano Eva , García Ernesto 
Published: March 2007

AbstractPhytoalexins are secondary metabolites that in legumes are typically isoflavonoid derivatives. Techniques for their measurement very often use determination of the UV absorbance of ethanol extracts to avoid time‐consuming extractions and the use of expensive solvents. However, other phenolic compounds also give UV absorbances interfering with quantitative determinations. A microassay is proposed to extract and measure bean phytoalexins from intact, viable, bean leaf protoplasts. Protoplasts as a tool for measuring phytoalexin elicitor stimulation is discussed.
Reverse‐phase high pressure liquid chromatographic analysis of hydroxycoumarins in plant extracts. Quantitative determination of hydroxycoumarins in Fraxinus ornus
Authors: Nykolov Nykolay , Iossifova Tanya , Vassileva Elka , Kostova Ivanka , Stoev Georgi 
Published: March 2007

AbstractA reverse‐phase high pressure liquid chromatographic determination of 11 hydroxycoumarins in plant extracts is described, which is applicable to the quantitative analysis of these compounds for industrial purposes. Fraxinus ornus bark from various regions in Bulgaria showed differences both in the total coumarin content and in the relative proportions of each component. The occurrence of 7‐methylesculin and 6,7,8‐trihydroxycoumarin in the family Oleaceae is reported for the first time.
Biosynthetic relationship of aromoline and berbamine in cultured roots of Stephania cepharantha
Authors: Sugimoto Yukihiro , Kawaminami Shunro , Yamada Yasuyuki 
Published: March 2007

AbstractCultured roots of Stephania cepharantha, rich in the bisbenzylisoquinolines aromoline (1) and berbamine (2), were fed [3‐13 C]tyrosine. The labelled alkaloids were isolated. 13C NMR spectra showed that 13C was specifically incorporated into sites on 1 and 2. The ratios of 13C enrichment for the benzyl and isoquinoline portions of 1 and 2 were the same within the experimental limits, evidence that both alkaloids are derived from a common intermediate.
Qualitative and quantitative determination of taxol and related compounds in Taxus cuspidata Sieb et Zucc
Authors: Fang Weishuo , Wu Yue , Zhou Jinyun , Chen Weiming , Fang Qicheng 
Published: March 2007

AbstractIn this paper the determination of taxol and the related compounds 10‐deacetyltaxol, cephalomannine and 10‐deacetylcephalomannine in various parts of Taxus cuspidata Sieb et Zucc. is reported. All four compounds were well separated on a 5 μm Spheri‐5 RP‐18 column with a mobile phase composed of water:acetonitrile:tetra‐hydrofuran (55:35:10). The concentrations of these compounds are quite different for different parts of the plant and are highest in stem bark. Furthermore, the content is related to the age of the plant, the older plants containing larger quantities of taxane diterpenoids. We have also found that the contents of taxol and related compounds in the shrub are usually higher than those in the tree.
Determination of cinnamic acid and 4‐coumaric acid in alfalfa (Medicago sativa L.) cell suspension cultures by gas chromatography
Authors: Orr John D. , Sumner Lloyd W. , Edwards Robert , Dixon Richard A. 
Published: March 2007

AbstractA capillary gas chromatographic (GC) method for the assay of cinnamic acid and 4‐coumaric acid in alfalfa (Medicago sativa L.) cell extracts is described. These compounds were assayed as their trimethylsilyl derivatives; hydrocinnamic acid was used as the internal standard for quantifications. This method was qualitatively validated by GC/mass spectral analysis and quantitatively validated by measuring the extraction recovery from alfalfa cells, the recovery from derivatization, the stability of silylated derivatives, the limits of detection, the linearity of the detector response to increasing amounts of analytes, and the intra‐ and inter‐assay precisions. Cinnamic acid and 4‐coumaric acid were present in alfalfa cell extracts and were resolved from all other components by this method. As little as 4 pmol of each acid could be quantified, and the detector response was linear over a range covering five orders of magnitude. The cellular concentrations of free cinnamic acid and 4‐coumaric acid ranged from ca. 5–100 μmol/kg fresh weight tissue.
Measurement of latent polyphenol oxidase activity in the presence of the divalent cations Ca+2, Mg+2 and Mn+2
Authors: Jiménez Mercedes , García‐Carmona Francisco 
Published: March 2007

AbstractIn the present paper the specific effect of divalent cations on the measurement of the catecholase activity of latent polyphenol oxidase, extracted from Gamay grape suspension cultures, is analysed. The optimum conditions for the activation process produced by the divalent cations have been examined with respect to cation concentration and the pH of the reaction medium. This activation has also been studied with regard to the kinetic parameters of the enzyme in its catalytic expression on 4‐methylcatechol. In order to maximize the catalytic capacity of latent polyphenol oxidase it is necessary to measure the enzymic activity in the presence of divalent cations such as Ca+2, Mn+2 or Mg+2.
The application of thermal desorption‐gas chromatography‐mass spectrometry to the analyses of flower volatiles from five varieties of oilseed rape (Brassica napus spp. oleiferd)
Authors: Robertson G. W. , Griffiths D. W. , Smith W. MacFarlane , Butcher R. D. 
Published: March 2007

AbstractThermal desorption coupled to capillary gas chromatography‐mass spectrometry has been used to identify volatile chemicals released from the flowers of five varieties of oilseed rape. An entrainment apparatus for volatile headspace analysis is described. The major classes of compound found were organic sulphides, C4 substituted compounds, aldehydes and terpenes. The possible role of these compounds in the human allergic‐type response associated with oilseed rape is discussed.
Selective extraction of phenolic components from Ginkgo biloba extracts using supercritical carbon dioxide and off‐line capillary gas chromatography/mass spectrometry
Authors: Verotta Luisella , Peterlongo Federico 
Published: March 2007

AbstractA method has been developed for the extraction and analysis of phenolic components from crude extracts of Ginkgo biloba by supercritical fluid extraction with carbon dioxide combined with off‐line capillary gas chromatography/mass spectrometry. Class‐selective extraction has been performed with a single supercritical fluid by varying the extraction conditions. This method is applicable to the scale‐up, isolation and identification of toxic phenolic components in commercial extracts of G. biloba.
Simultaneous analysis of monoterpenes and diterpenoids of conifer oleoresin
Authors: Lewinsohn Efraim , Savage Thomas J. , Gijzen Mark , Croteau Rodney 
Published: March 2007

AbstractA simple and rapid procedure for the simultaneous determination of monoterpenes and diterpenoid resin acids of conifer stem oleoresin is described; it involves tissue extraction with methyl tert‐butyl ether and methylation of the resin acids with CH2N2. The resin acid methyl esters and the monoterpenes are then analysed in a single gas chromatographic step. Enantiomer composition of the major monoterpene constituents is determined, after preliminary purification by thin layer chromatography, by capillary gas chromatography on a cyclodextrin column. The method is applicable to conifer species of high resin content (Iodgepole pine) and low resin content (grand fir).
Estimation of phyllanthin and hypophyllanthin by high performance liquid chromatography in Phyllanthus amarus
Authors: Sharma Anupam , Singh Ravneet T. , Handa Sukhdev S. 
Published: March 2007

AbstractA reversed phase high performance liquid chromatographic procedure for standardizing a popular hepatoprotective Indian herb “Bhumyamlaki” (Phyllanthus amarus) on the basis of two of its bioactive lignans, phyllanthin and hypophyllanthin, has been developed. The method has been found to be sensitive, precise and to record more than 98% recovery of the two lignans. The leaves of P. amarus were found to contain the highest amounts of phyllanthin (0.7% w/w) and hypophyllanthin (0.3% w/w) as compared to the other parts of the plant.
Off‐line supercritical fluid extraction—high resolution gas chromatography applied to the study of moraceae species
Authors: Vilegas Janete H. Y. , Lanças Fernando M. , Vilegas Wagner , Pozetti Gilberto L. 
Published: March 2007

AbstractSupercritical fluid extraction with CO2, performed in a home‐made system, of rhizomes of Dorstenia bryoniifolia Mart, ex Miq. (Moraceae) and of bark roots of Brosimum gaudichaudii Trécul (Moraceae) afforded crude extracts that were analysed by high resolution gas chromatography (HRGC). The D. bryoniifolia extract contained, besides the previously reported pimpinelin and isobergapten, the furocoumarins psoralen, bergapten, isopimpinelin and the triterpenes α‐ and β‐amyrin and the acetate of the latter. The B. gaudichaudii extract contained a number of terpenoids as well as the previously reported psoralen and bergapten. Supercritical fluid extraction gave extracts qualitatively similar to those obtained by Soxhlet extraction with hexane and, together with off‐line HRGC, was shown to be a fast and accurate technique to be used in rapid phytochemical examination.
A high performance liquid chromatographic method for the separation of hexose monophosphates and UDP glucose from plant extracts and its use to determine specific activities in radiotracer experiments
Authors: Viola R. , Davies H. V. , Sommerville L. B. 
Published: March 2007

AbstractAnion exchange high performance liquid chromatography (HPLC) was used to separate UDP glucose (UDPGlc) and hexose monophosphates (HMPs) in crude ethanol extracts of potato tubers. Detection and quantification of UDPGlc and [U‐14C]UDPGlc was achieved with UV (A254) and radioactivity monitors connected in series. The 14C content in glucose 6‐phosphate (Glc‐6‐P), fructose 6‐phosphate (Fru‐6‐P) and glucose 1‐phosphate (Glc‐1‐P) was obtained following their enzymatic conversion to gluconate 6‐P and subsequent separation by HPLC. Individual HMPs were quantified by enzyme‐coupled reaction systems using a microplate reader equipped with a 340 nm filter. This approach allowed the specific activities of UDPGlc, Glc‐6‐P, Fru‐6‐P and Glc‐1‐P to be quantified in radiolabelled potato extracts within 2 h.
Determination of the sesquiterpene dialdehyde polygodial by high‐pressure liquid chromatography
Authors: van Beek Teris A. , van Dam Nicole , De Groot Aede , Geelen Threes A. M. , van der Plas Linus H. W. 
Published: March 2007

AbstractA high‐pressure liquid chromatographic procedure for the determination of the antifeedant polygodial in Polygonum hydropiper leaves was developed. For leaves, the method consists of a selective extraction with hexane: EtOAc (8:2), pre‐purification of the evaporated extract over a solid phase C2 column, separation with a C18 RP‐HPLC column and detection/quantitation by means of UV at 233 nm. As internal standard α‐ionone is used. Advantages of the method are its selectivity and speed. Various aspects such as extraction efficiency, recovery, peak purity and reproducibility have been evaluated. The minimal detectable quantity is 1 ng.
Gas chromatography ‐ isotope ratio mass spectrometry measurements of some carboxylic esters from different apple varieties
Authors: Karl Volker , Dietrich Armin , Mosandl Armin 
Published: March 2007

AbstractThe δ13CPDB‐values of some carboxylic esters from apple flavours have been determined by capillary gas chromatography, on‐line coupled with isotope ratio mass‐spectrometry (GC‐IRMS) and compared with the isotopic ratios of some commercially available samples. For the first time, the chirospecific measurement of the isotopic ratios of 2‐methylbutanoates is described. Enantioselective capillary gas chromatography (enantio‐GC), GC‐IRMS as well as enantio‐GC‐IRMS are demonstrated as sophisticated methods in monitoring the authenticity of natural flavour compounds.
High performance liquid chromatographic analysis of aliphatic lichen acids
Authors: Huneck Siegfried , Feige Guido Benno , Lumbsch H. Thorsten 
Published: March 2007

AbstractAliphatic lichen acids can be transformed into their phenacyl esters which show strong absorption in the UV (ca. λ = 240 nm) and which can be used to detect these compounds following high performance liquid chromatography. Other suitable derivatives are the p‐nitrophenyl and benzyl esters, as well as the benzoates of the alcohols prepared from the acids by reduction of the corresponding methyl esters with lithium aluminium hydride.
Chiral compounds of essential oils XIV: Simultaneous stereoanalysis of buchu leaf oil compounds
Authors: Köpke Thomas , Dietrich Armin , Mosandl Armin 
Published: March 2007

AbstractMultidimensional enantioselective gas chromatography, employing heart‐cutting from a non‐chiral precolumn onto a selectivity adjusted, modified cyclodextrin coated chiral main column, permits the simultaneous stereo differentiation of the chiral major compounds of buchu leaf oil. Commercially available essential oil as well as laboratory prepared samples were directly analysed. The enantiomeric distribution of limonene, menthone, isomenthone and pulegone was investigated, and the characteristic flavour impact compounds, 3‐oxo‐p‐menthane‐8‐thiol and its thiol acetate, were stereoanalysed. Their chirality evaluation is discussed as an indicator of authenticity of ‘cassis’ type fruit aromas and fragrances.
Diterpenes from the brown alga Dilophus mediterraneus
Authors: Goez Christiane E. , Wright Anthony D. , König Gabriele M. , Sticher Otto 
Published: March 2007

AbstractFrom the dichloromethane extract of the brown alga Dilophus mediterraneus nine diterpenes, belonging to different skeletal classes, were isolated and characterised spectroscopically (MS, NMR, UV and IR). The structure of a new natural diterpene (1R*, 2E, 4R*, 7E, 11R*, 12S*)‐12, 18‐dihydroxydolabella‐2,7‐diene) was resolved with the aid of the lanthanide shift reagent Europium(III)‐tris(1,1,1,2,2,3,3)‐heptafluoro‐7,7‐dimethyl‐d6‐octa‐4,6‐dion‐d3, C30H3D27EuF21O6, (Eu(fod)3).
Separation and quantitation of stevioside and rebaudioside a in plant extracts by normal‐phase high performance liquid chromatography and thin‐layer chromatography: A comparison
Authors: Nikolova‐Damyanova Boryana , Bankova Vasya , Popov Simeon 
Published: March 2007

AbstractTwo similar methods, normal phase high performance liquid chromatography and silica gel thin‐layer chromatography with densitometry, were applied for the separation and quantitative determination of the diterpene glycosides stevioside and rebaudioside A in the leaves of the plant Stevia rebaudiana Bertoni. Results were compared and found to be very close in all basic features: resolution, accuracy and reproducibility. Thin‐layer chromatrography was found to be more suitable in case of phytochemical screening of large number of samples.
Desorption chemical ionization mass spectrometry of C‐glycosylflavones
Authors: Bakhtiar A. , Gleye J. , Moulis C. , Fourasté I. 
Published: March 2007

AbstractSeventeen natural C‐glycosylflavones have been analysed using positive desorption chemical ionization mass spectrometry with ammonia as reagent gas. This technique provides the molecular weight, information for the identification of the aglycone, the sugar sequence, and the characterization of the C‐sugar (hexose, pentose). The distinction between mono‐C‐glycosylflavones, di‐C‐glycosylflavones, C‐glycosylflavone 2″‐O‐glycosides, and di‐C‐glycosylflavone 2‴‐O‐glycosides is also obtained.
A comparison of gas chromatography and high performance liquid chromatography for artemisinin analyses
Authors: Ferreira Jorge F. S. , Charles Denys J. , Wood Karl , Janick Jules , Simon James E. 
Published: March 2007

AbstractAn improved method for high performance liquid chromatography with electrochemical detection (HPLC‐EC) is presented for artemisinin analysis. It involves increased concentration of organic phase, elimination of the degassing step in sample preparation, and reduced time for heating and degassing in mobile phase preparation and recycling. The HPLC‐EC method was compared to a gas chromatographic (GC) method, which measured artemisinin indirectly through two of its degradation products, labelled A and B. Both methods provided a good separation of artemisinin from artemisitene, arteannuin B, and the semisynthetic dihydroartemisinin. Peak B provided a higher correlation to the levels of artemisinin detected by HPLC‐EC. Peaks A, B and Z (a small peak preceding A and B) were identified through electron impact and chemical ionization spectra from GC‐mass spectral analysis.