bluuebunny/crossref_metadata_2025_split huggingface dataset:
Extraction of purine alkaloids from cocoa tissues and determination by high‐performance liquid chromatography
Authors: Gurney Kären A. , Evans L. V. , Robinson David S. 
Published: March 2007

AbstractProtocols for the extraction and quantification by high‐performance liquid chromatography of purine alkaloids from cocoa beans, Theobroma cacao plants and tissues cultivated in vitro have been developed. These allow the rapid determination of 7‐methylxanthine, 3‐dimethylxanthines and caffeine from complex mixtures and represent improvements over published methods. Alkaloids were extracted in boiling water and the extracts clarified by precipitation and filtration. Chromatography was carried out using C18 reverse‐phase columns with isocratic elution. The eluate was monitored routinely at 280 nm and compounds quantified using external standards. Estimations of purine alkaloid recoveries were better than 98% for caffeine, theobromine and theophylline. Reproducibility of replicate injections averaged 99% with coefficients of variation between replicate extractions typically less than 5% except for small samples (i.e., less than 0.2 g dry weight). Results for cocoa nibs and shells; roots, stem, green and red leaves of the cocoa plant; callus and suspension‐cultured cells and growth media from one type of cocoa are reported.
Selective INEPT spectroscopy–‐A powerful tool for the spectral assignment and structure elucidation of natural products
Authors: Cordell Geoffrey A. 
Published: March 2007

AbstractThe one‐dimensional, J‐modified, proton‐carbon correlation technique, known as the selective INEPT technique, has proved to be a powerful tool for both unambiguous carbon and proton spectral assignment and also provides critical carbon framework information.
Carbonic anhydrase catalysed hydrolysis of fluorogenic esterase substrates
Authors: Cohen Jason D. , Husic H. David 
Published: March 2007

AbstractCarbonic anhydrases from spinach leaves, Chlamydomonas reinhardtii and bovine erythrocytes were examined for their ability to hydrolyse the fluorogenic esterase substrates 7‐acetoxy‐4‐methylcoumarin, 7‐acetoxycoumarin‐3‐carboxylic acid and fluorescein diacetate. The spinach enzyme was unable to hydrolyse any of the three substrates, however, the C. reinhardtii enzyme hydrolysed 7‐acetoxy‐4‐methylcoumarin and fluorescein diacetate, but at a much slower rate than the bovine erythrocyte enzyme which hydrolysed all three substrates. A method was developed to assay purified carbonic anhydrase from C. reinhardtii based on the enzyme‐catalysed hydrolysis of fluorescein diacetate.
Use of evaporative light scattering mass detection in high performance liquid chromatography of triterpenes in the bark resin of betula species
Authors: Taipale Hannu T. , Lapinjoki Seppo P. 
Published: March 2007

AbstractPlants often contain triterpenes that are difficult to analyse by high performance liquid chromatography (HPLC) due to lack of double bonds or other chromophores that can be readily detected spectrophotometrically. The present results show that light scattering mass detection (LS) is useful in such cases. We have been able to replace thin layer chromatography (TLC) with HPLC by using LS in evaluating triterpene contents in the bark resin of different birches (Betula pendula Roth., B. resinifera (Regel) Fern. & Raup., B. platyphylla Sucachev, B. ermanii Cham., B. papyrifera Marsh and B. pubescens Ehrh.). LS was five‐fold more sensitive than UV for papyriferic acid, which was used as a reference compound, and HPLC/LS revealed new compounds and qualitative relations that were undetectable by UV or TLC. This paper describes detection of a new major triterpenoid from B. pendula, the age dependency of the triterpenoid content in B. pendula and B. papyrifera and gives an interspecies comparison of the triterpenoid content of the different species.
Application of on‐line HRGC‐FTIR spectroscopy to the analysis of acetylenic flavour precursors
Authors: Winterhalter Peter , Full Gerhard , Herderich Markus , Schreier Peter 
Published: March 2007

AbstractAroma extracts from various plants were screened for acetylenic flavour precursors using on‐line HRGC‐FTIR spectroscopy. Selected wavelength monitoring (2100–2250 cm−1) revealed for the first time the presence of 3‐hydroxy‐7,8‐didehydro‐β‐ionone in peelings of lulo syn. naranjilla (Solanum vestissimum D.) fruit. The same compound was also detected as a major aglycone after enzymatic hydrolysis of a glycosidic extract isolated from Vitis vinifera cv. Riesling leaves. The related acetylenic diol, 3‐hydroxy‐7,8‐didehydro‐β‐ionol, was similarly identified as the aglycone in a glycosidic extract obtained from purple passion fruit (Passiflora edulis Sims) juice. The discovery of these acetylenes is discussed with regard to the formation of β‐damascenone in plants.
Quantitative enzyme cytochemistry in plant biotechnology
Authors: Gahan P. B. 
Published: March 2007

AbstractImmunocytochemistry, one of the two basic approaches to the in situ study of enzymes, allows the enzyme molecules to be localized, but indicates nothing about their activity. Quantitative cytochemistry, on the other hand, indicates the sites of localization of enzyme activity and, in many cases, the rates of these activities. This latter approach, which is the subject of this review, permits the assessment of activity in individual cells or groups of cells in a given tissue. Details of tissue preparation, enzyme procedures, methods of quantification and some case histories illustrate the specificity and flexibility of the method.
Unambiguous nuclear magnetic resonance assignments for swainsonine, an indolizidine alkaloid with α‐mannosidase inhibitory activity
Authors: Kardono Leonardus B. S. , Kinghorn A. Douglas , Molyneux Russell J. 
Published: March 2007

AbstractThe proton and carbon‐13 nuclear magnetic resonance (NMR) spectra of swainsonine, (1S,2R,8R,8R,8aR)‐1,2,8‐trihydroxyoctahydroindolizine, isolated from the seeds of Astragalus oxyphysus A. Gray, have been reassigned through the use of two‐dimensional NMR techniques. Unambiguous NMR spectral data have also been determined for swainsonine 1,2,8‐triacetate.
Separation of iridoids by vacuum liquid chromatography
Authors: Handjieva Nedjalka , Saadi Houcine , Popov Simeon , Baranovska Iskra 
Published: March 2007

AbstractVacuum liquid chromatography (VLC) was used for the separation of iridoids isolated from Valeriana officinalis L. and Centranthus ruber D. C. (Valerianaceae), Plantago media L. (Plantaginaceaea), Viburnum lantana L. (Caprifoliaceae), Gentiana punctata L. and Erythraea centaurium Pers. (Gentianaceae). The advantages of the technique over preparative thin layer chromatography and open‐column chromatography are discussed. Decapetaloside was isolated from V. lantana for the first time as were sweroside and swertiamarin from G. punctata. Florisil was used for the first time as an adsorbent for VLC.
Investigation of extracts of plant cell cultures by proton nuclear magnetic resonance spectroscopy
Authors: Schripsema Jan , Verpoorte Robert 
Published: March 2007

AbstractA method for the rapid phytochemical characterization of plant cell cultures, using proton nuclear magnetic resonance spectroscopy (1H NMR), is described. Aqueous extracts were prepared from a large number of plant cell suspension cultures. Following lyophilization, the extracts were redissolved in D2O containing an internal standard to enable quantification and 1H NMR spectra were measured. In the spectra, signals from sugars and amino acids were observed. The patterns obtained were characteristic of cell lines, with related lines typically showing similar characteristics, e.g., Tabernaemontana suspension cultures are characterized by their ability to accumulate large amounts of arginine, while Catharanthus cultures mainly accumulate glutamine. The amounts of amino acids accumulated were found to be determined mainly by the medium on which the cell cultures were growing. Murashige and Skoog medium supported nitrogen storage in amino acids, while Gamborg B5 medium did not. Reference spectra of some of the most common constituents are presented, together with data enabling a direct quantification of these compounds in aqueous extracts.
Multidimensional gas chromatography/mass spectrometry: A powerful tool for the direct chiral evaluation of aroma compounds in plant tissues. II. Linalool in essential oils and fruits
Authors: Bernreuther Alexander , Schreierc Peter 
Published: March 2007

AbstractOn‐line coupled multidimensional gas chromatography (DB‐5/Lipodex C)/mass spectrometry was used for direct chiral analysis of linalool in 15 essential oils and 16 fruit species. Whereas in a number of commercial essential oils racemic linalool was found, in the corresponding oils prepared in the laboratory enantioselective distribution of linalool was determined. Among the fruits studied, (R)‐(−)‐linalool dominated in guava, greengage, lulo (Solanum vestissimum), peach and plum. In arctic bramble, mango, yellow passion fruit, raspberry and strawberry the (S)‐(+)‐enantiomer prevailed. The occurrence of approximately racemic linalool was established in apricot [(enantiomeric excess (ee) 6.0% (R)], mirabelle plum [ee 9.4%(R)], red passion fruit [ee 9.0% (R)] and pineapple [ee 6.6% (R)].
Structure elucidation of cyanidin‐3‐sambubioside and assignments of the 1H and 13C NMR resonances through two‐dimensional shift‐correlated NMR techniques
Authors: Andersen Øyvind M. , Aksnes Dagfinn W. , Nerdal Willy , Johansen Ole‐P. 
Published: March 2007

AbstractThe anthocyanin cyanidin‐3‐sambubioside was isolated from the acidified methanolic extract of the fruits of Sambucus nigra by successive application of an ion exchange resin, droplet countercurrent chromatography and gel filtration. By means of chemical degradation and spectroscopy (especially one‐ and two‐dimensional NMR techniques) the structure has been determined to be cyanidin‐3‐O‐β‐D‐xylopyranosyl‐(1±2)‐β‐D‐glucopyranoside with both the sugar rings assuming a 4C1 chair conformation.The combination of several NMR techniques such as double‐quantum filtered proton‐proton shift correlation (DQF‐COSY), homonuclear Overhauser enhancement (NOE) difference spectroscopy, heteronuclear coupling‐modulated spin echo, proton‐carbon shift correlation optimized for direct (HSC) and long‐range coupling (COLOC) provided assignments of the 1H and 13C signals. The coupling constants of the sugar protons were obtained by iterative spin simulation. This is the first report of a heteronuclear shift correlation experiment applied on anthocyanins.
Determination of cyclic 3′,5′‐adenosine monophosphate in plant tissues by high performance liquid chromatography
Authors: Yavorskaya V. K. , Dragovoz I. V. , Savinsky S. V. , Markova V. E. , Sh. Kofman I. 
Published: March 2007

AbstractA quantitative method has been developed for determining cyclic 3′,5′‐adenosine monophosphate (cAMP) in plant tissues based on the use of high performance liquid chromatography following partial purification of cyclonucleotides from plant extracts by different chromatographic procedures. The identical nature of a plant cAMP‐like substance and synthetic cAMP has been demonstrated. The lower limit of cAMP detection was 2.6 ng, the overall efficiency of determination was 34.0% and the standard deviation was ±5.2%. The concentration of cAMP in rye seedlings was determined to be 0.700±0.069 n mol per g fresh weight of tissue.
Quantitative determination by high performance liquid chromatography and microspectro‐fluorimetry of phenolic acids in maize grain
Authors: Sen A. , Miller S. S. , Arnason J. T. , Fulcher R. G. 
Published: March 2007

AbstractA method for improved recoveries of phenolic acids in maize grain extracts and their quantification by high performance liquid chromatography (HPLC) is described. A quantitative imaging technique to determine mean ferulic acid autofluorescence of ground grain samples was found to be correlated (r=0.86, n=14, P=0.05) with HPLC analysis of ferulic acid in a wide range of different maize genotypes. The advantage of the imaging method is that it reduces procedures required and analysis time considerably.
Structure of petanin, an acylated anthocyanin isolated from solanum tuberosum, using homo‐and hetero‐nuclear two‐dimensional nuclear magnetic resonance techniques
Authors: Andersen Øyvind M. , Opheim Sigrid , Aksnes Dagfinn W. , Frøystein Nils Åge 
Published: March 2007

AbstractThe anthocyanin, petanin, was isolated from the acidified methanolic extracts of blue tubers of the potato (Solanum tuberosum) by successive application of ion exchange chromatography, droplet counter‐current chromatography and gel filtration. The full structure, petunidin 3‐O‐[6‐O‐(4‐O‐E‐p‐coumaroyl‐α‐L‐rhamnopyranosyl)‐β‐D‐glucopyranoside]‐5‐O‐β‐D‐glucopyranoside, with both the glucopyranose rings assuming a4C1 chair conformation and the rhamnopyranose ring assuming a 1C4 chair conformation, was elucidated by means of chemical degradation, chromatography and spectroscopy, especially homo‐ and hetero‐nuclear two‐dimensional nuclear magnetic resonance techniques.
The determination of double bond positions in polyunsaturated fatty acids–‐Gas chromatography/mass spectrometry of the diethylamide derivative
Authors: Nilsson Ralf , Liljenberg Conny 
Published: March 2007

AbstractDiethylamides were prepared from polyunsaturated long‐chain fatty acids and were examined by gas chromatography/mass spectrometry. The spectra contained informative ions which allowed immediate recognition of the position of the original double bonds. The derivatives were easily prepared in one step and were baseline‐separated on the gas chromatographic column at moderate temperatures. This method was suitable for samples of long‐chain fatty acid mixtures.
Multidimensional gas chromatography/mass spectrometry (MDGC/MS): A powerful tool for the direct chiral evaluation of aroma compounds in plant tissues. III. (1S)‐(–‐)‐2‐endo‐Acetoxy‐3‐exo‐hydroxybornane (vulgarole) in mugwort (Artemisia vulgaris L.) herb
Authors: Wörner Martin , Schreier Peter 
Published: March 2007

AbstractOn‐line coupled multidimensional gas chromatography (DB‐5/Lipodex D)/mass spectrometry (MDGC/MS) revealed the occurrence of (1S)‐(–‐)‐2‐endo‐acetoxy‐3‐exo‐hydroxybornane (vulgarole) with 100% enantiomeric excess in mugwort (Artemisia vulgaris L.) herb. The result was verified by means of synthesized optically pure (1R) and (1S) enantiomers of vulgarole.
A high performance liquid chromatographic procedure for the analysis of tobacco alkaloids‐‐Application to the evaluation of tobacco alkaloids in plants and cell suspension cultures
Authors: Manceau Francoise , Fliniaux Marc‐Andre , Jacquin‐Dubreuil Annie 
Published: March 2007

AbstractA high performance liquid chromatographic (HPLC) procedure for the analysis of tobacco alkaloids in plant material is described. It allows the detection of up to 10 ng of nicotine, nornicotine, anabasine and nicotinic acid. It is more efficient with regard to the sensitivity, simplicity and suitability for phytochemical analysis than the gas chromatographic (GC) procedure previously used by the authors. Alkaloid extraction and purification prior to HPLC analysis can be carried out more quickly and easily. The method has been applied to the study of the bioconversion of nicotine into nornicotine by Nicotiana plumbaginifolia cell suspensions. The yield of biotransformation which was estimated at 53.2% by GC analysis is now found to be nearly 100% by HPLC analysis. Moreover, it has been shown that the method is reliable for the evaluation of high or low quantities of endogenous alkaloids produced by plant organs or tissue cultures.
The enhanced role of a lanthanide shift reagent in the structure elucidation and 1H NMR and 13C NMR characterization of some marine natural products
Authors: Wright Anthony D. , König Gabriele M. , Sticher Otto 
Published: March 2007

AbstractThree marine‐derived natural products, 1, 2 and 3, were used to demonstrate the enhanced role of a 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)] in the structure elucidation of compounds containing a single hydroxyl function. The value of reagents of this type, both as an aid to structure solution as well as in the complete assignment of 1H NMR and 13C NMR resonances, is clearly demonstrated as a consequence of the development of proton‐detected proton‐carbon correlated 2D‐NMR methodologies.
A new chromatographic method for the isolation of (−)‐Δ9‐(trans)‐tetrahydrocannabinolic acid A
Authors: Lehmann T. , Brenneisen R. 
Published: March 2007

Abstract(−)‐Δ9‐(trans)‐Tetrahydrocannabinolic acid A (THCA‐A), which is the main cannabinoid in ripe plants and the biogenetk precursor of the psychoactive (−)‐Δ9‐(trans)‐tetrahydrocannabinol, has been isolated from Cannabis sativa L. After extraction with petroleum ether and subsequent fractionation using alkali and diethyl ether, purification was performed by medium pressure liquid chromatography to yield an amorphous >99% pure powder. THCA‐A was characterized by its chromatographic and spectroscopic data.
Rapid screening assay of cyanide content of cassava
Authors: Bradbury J. Howard , Egan Sylvia V. 
Published: March 2007

AbstractA rapid, inexpensive screening assay was developed in order to measure the cyanide content of cassava (Manihot esculenta Crantz) tubers. A small disc of parenchyma tissue cut with a cork borer or alternatively grated tissue was placed in a stoppered glass tube and the hydrogen cyanide liberated produced a blue colour on a filter paper previously spotted with a drop of tetra‐base [4,4'‐methylenebis‐(N,N‐dimethylaniline)] and cupric acetate. The intensity of the blue colour which developed within one hour was rated visually on a graded scale from 0 to 5. The correlation coefficient between samples accurately analysed for total cyanide and also tested using the rapid assay was 0.77.
Assay of the thiobarbituric acid‐reactive products of lipid peroxidation in plants using derivative absorption spectroscopy
Authors: Merzlyak Mark N. , Zhigalova Tatyana V. , Shevyryova Varvara V. 
Published: March 2007

AbstractThe spectrophotometric determination of 2‐thiobarbituric acid‐reactive products of lipid peroxidation in plants is limited because of the presence of substances forming coloured complexes with the reagent as well as water‐soluble pigments. In order to overcome this interference 2nd derivative analysis of the absorption spectra was applied. The results of the study indicate that the method can be performed using cotton and maple leaves that contain high amounts of anthocyanins and bifunctional aldehydes, respectively. The accumulation of lipid peroxidation products was observed in cotton plants treated with the herbicide diquat. In wheat roots the band of malondialdehyde‐thiobarbituric acid absorption was not resolved either in intact or in diquat‐treated plants, because of the production of a chromophore with an absorption maximum at 551 nm. The sensitivity of the 2nd derivative determination of malondialdehyde is about 0.2 μ. A linear response was observed up to 8–10 μ of the aldehyde.
Quantitative analysis of serpentine and ajmalicine in plant tissues of Catharanthus roseus and hyoscyamine and scopolamine in root tissues of Datura stramonium by thin layer chromatography‐densitometry
Authors: Monforte‐González M. , Ayora‐Talavera T. , Maldonado‐Mendoza I. E. , Loyola‐Vargas V. M. 
Published: March 2007

AbstractSensitive and rapid thin layer chromatographic‐densitometric methods have been developed for the quantification of the indole alkaloids, ajmalicine and serpentine, and of the tropane alkaloids, hyosycamine and scopolamine. The concentration ranges in which accurate and reproducible results can be obtained are 1‐8 μg for the tropane alkaloids, 1‐10 μg for ajmalicine and 200–1400 ng for serpentine. The limit of detection for serpentine is 20 ng and 500 ng for the other alkaloids. The methods have been successfully employed for the determination of alkaloids in tumours and calli of Catharanthus roseus, in root tissues of Datura stramonium and also in the respective liquid culture media.
Extraction and biossay‐directed fractionation of the cytotoxic metabolites from Chelidonium majus
Authors: De Giulio A. , De Rosa S. , Di Vincenzo G. , Strazzullo G. 
Published: March 2007

AbstractAn exhaustive extraction model and a general adsorption chromatographic method involving a rapid stepgradient are described for the initial fractionation of weakly‐ and non‐polar fractions from Chelidonium majus L. Fractionation and purification of cytotoxic metabolites were directed by bioassay using the Artemia salina test.
A rapid quantitative method for the analysis of sesquiterpene phytoalexins by high performance liquid chromatography
Authors: Moreau Robert A. , Preisig Carol L. , Osman Stanley F. 
Published: March 2007

AbstractA new high performance liquid chromatographic technique has been developed for the rapid analysis of sesquiterpene phytoalexins such as capsidiol, rishitin, lubimin and phytuberol. This method employs a cyanopropyl‐bonded phase column with an isocractic mixture of hexane and isopropanol. When used with a flame ionization detector the lower limits of detection are about 0.1 μg and the response of the detector is linear in the range 0.1–30 μg. With the UV detector at 205 nm, the lower limits of detection are about 0.1 μg for capsidiol and rishitin and 0.5 μg for lubimin, phytuberol and debneyol. The response of the UV detector is linear in the range 0.5–30 μg. Although both detectors proved to be useful, the signal response with the flame ionization detector was proportional to the mass of each of the phytoalexins, while the signal with the UV detector was proportional to the number of carbon‐carbon double bonds in each of the compounds.
Standardization of the indian crude drug kalmegh by high pressure liquid chromatographic determination of andrographolide
Authors: Sharma Anupam , Lal Krishan , Handa Sukhdev S. 
Published: March 2007

AbstractThe popular hepatoprotective Indian herbal drug Kalmegh (Andrographis paniculata) can be standardized by high pressure liquid chromatographic determination of its major active constituent, andrographolide. The leaves of the herb were found to contain the highest amount (2.39%w/w) of andrographolide and the seeds to contain the lowest. The technique was found to be much more sensitive and simple than the known spectrophotometric method.
The analysis of phytoecdysteroids in single (preflowering stage) specimens of fat hen, Chenopodium album
Authors: Dinan Laurence 
Published: March 2007

AbstractA simple microextraction procedure together with an ecdysteroid‐specific radioimmunoassay (RIA) have been used to quantify the levels of phytoecdysteroid in small (<50 mg dry wt.) samples of plant tissues during the development of Chenopodium album. The existence of a distinct concentration gradient of phytoecdysteroids within the aerial portions has been confirmed by the detailed analysis of ecdysteroid titres throughout single plants. Ecdysteroid concentration increased steadily up the main stem of the plant. This pattern was reflected in the main leaves and in the petioles associated with the main leaves. The ecdysteroid concentration in the growing tip was higher than those at the top of the stem or in the uppermost leaves. High concentrations were also present in the roots. The distinct concentration gradient characteristic of the main stem, associated leaves and growing tip recurred in each of the side‐shoots on a mature plant. The identity of the RIA‐positive material is essentially identical in most parts of the plant, being mainly 20‐hydroxyecdysone (20OHE) and polypodine B (PolB; 5β,20‐dihydroxyecdysone) with much smaller amounts of more polar and less polar unidentified compounds. In the oldest leaves, the contribution of 20OHE and PolB is reduced and new polar and apolar compounds are found, indicating that catabolism of phytoecdysteroids occurs as leaves begin to senesce.