[Sitemap] [Contact] [Imprint] Deutsche Version Search site 

Phytochemical Analysis - Current Research Articles

Current research articles: Phytochemistry

The author- or copyrights of the listed research articles below are held by the respective authors or site operators, who are also responsible for the content of the presentations.

More current articles from Chemistry Journals same topic: see the navigation menu on the left.

To list your article here please contact us by eMail.

To search this web page for specific words type "Ctrl" + "F" on your keyboard (Command + "F" on a Mac). Then: type the word you are searching for in the window that pops up!

On this page considered journals:

Phytochemical Analysis - published by Wiley

Phytochemical Analysis devoted to the publication of original articles concerning the development, improvement, validation and/or extension of application of analytical methodology in the plant sciences. The spectrum of coverage is broad, encompassing methods and techniques relevant to the detection (including bio-screening), extraction, separation, purification, identification and quantification of compounds in plant biochemistry, plant cellular and molecular biology, plant biotechnology, the food sciences, agriculture and horticulture

Current articles of the journal:

Rapid Determination of Oligopeptides and Amino Acids in Soybean Protein Hydrolysates using High-Resolution Mass Spectrometry

Introduction Soybean protein hydrolysates (SPHs), especially oligopeptides, have shown a variety of functional properties, including immunomodulatory and anti-oxidant effects. Soybean protein hydrolysate products have been used as functional ingredients in food, sports nutrition or clinical nutrition. However, the mixture is mostly undefined due to its complex nature, containing peptides and minor amino acids as well as small proteins. Objectives To develop a specific and efficient method for the identification and structural characterisation of oligopeptides in SPHs, and to determine free amino acids in SPHs in the same analytical run, for evaluation of the chemical profile of SPH products. Methods Accurate mass spectrometry (MS) datasets of SPH samples were recorded on a high-performance liquid chromatography (HPLC) tandem high-resolution (HR) MS system. Potential oligopeptides were tentatively characterised based on their elemental compositions and ring double bond equivalent (RDBE) values, as well as HRMS/MS data. The analytical method to determine amino acids was evaluated in terms of linearity, precision, apparent recovery and limits of detection and quantitation. Results In total, 186 oligopeptides spanning the mass range of m/z 200–1500 and three major free amino acids could be determined in SPH samples in a single sample injection. Ninety-nine oligopeptides were tentatively characterised. The sensitive and specific instrumental performances also permitted the determination of 19 amino acids with a limit of quantitation of???0.1??g/mL. Conclusion The HPLC–HRMS technique has proven to be an advantageous tool for the rapid characterisation of oligopeptides and determination of amino acids in soybean protein hydrolysates. Copyright © 2014 John Wiley & Sons, Ltd.

Posted on 7 July 2014 | 6:28 am

Box–Behnken Design for Optimum Extraction of Biogenetic Chemicals from P. lanceolata with an Energy Audit (Thermal?×?Microwave?×?Acoustic): A Case Study of HPTLC Determination with Additional Specificity Using On-line/Off-line Coupling with DAD/NIR/ESI-MS

Introduction The genus Pluchea comprises about 80 species distributed worldwide, out of them, only Pluchea lanceolata (DC.) Oliv. & Hiern, is used extensively in the traditional system of India. No chromatographic method is available for its quality. Objectives To perform the energy audit for the extraction of biogenetic pentacyclic triterpene, its acetate and sterol from P. lanceolata utilising organic and four alternative solvents. Additionally to resolve the uncertainty of TLC determination, on-line/off-line coupling with a diode-array detector (DAD), and near-infrared (NIR) and electrospray ionisation (ESI) MS was introduced. Methods The extraction of taraxasterol (Tx), taraxasterol acetate (TxAc) and stigmasterol (St) from P. lanceolata was performed using three energy modes. The effects of different operating parameters were studied for optimum extraction yield using the design of experiments, that is, the central composite design and Box–Behnken design. In addition to the retention factor (Rf) and visible spectral matching, two additional optical spectroscopic techniques, that is, NIR and ESI-MS, were applied for extended specificity. Results The method was developed for Tx, TxAc and St determination using HPTLC at 645 nm. The optimum extraction yield of targeted compounds was found to be higher with organic solvents than eco-friendly surfactants. The pulse ultrasonic assisted extraction (PUAE) has resulted in optimum extraction of compounds comparable to hot extraction. Both NIR and ESI-MS provided extended specificity in determination. Conclusion The 5/1-PUAE was determined to be effective, reproducible, simple and energy efficient for the determination of Tx, TxAc and St in P. lanceolata. The offline coupling of NIR and ESI-MS with HPTLC led to considerable improvement in specificity. Copyright © 2014 John Wiley & Sons, Ltd.

Posted on 7 July 2014 | 6:28 am

Aroma Evaluation of Setonojigiku (Chrysanthemum japonense var. debile) by Hydrodistillation and Solvent-assisted Flavour Evaporation

Introduction The Chrysanthemum genus consisting of about 200 species is mainly distributed over the Northern Hemisphere. Despite the pleasant odour of C. japonense var. debile (setonojigiku), no detailed analysis of the aroma-active compounds has been reported using sensory evaluation. Objectives Using a hydrodistillation (HD) and a solvent-assisted flavour evaporation (SAFE) method to obtain the volatile oil from the leaf parts. Methods To clarify odorants contributing to the characteristic aroma-active compounds, the aroma-extract dilution analysis (AEDA) method was performed through gas chromatography olfactometry (GC/O) analysis. In addition, the odour activity value (OAV) was calculated in order to determine the relative contribution of each compound to the aroma-active compounds. Results A total of 42 components by HD oil were identified by GC–MS, whereas 34 components were identified in SAFE oil. Thirteen compounds were identified by GC/O analysis in HD and SAFE oils respectively. Conclusion Each extraction method has its own advantages and disadvantages, and they are generally complementary to each other. On the basis of AEDA, OAV and sensory evaluations, [2.2.1] bicyclic monoterpenes (borneol, bornyl acetate and camphor) and ?-caryophyllene are considered to be the main aroma-active compounds of both extraction methods. Copyright © 2014 John Wiley & Sons, Ltd.

Posted on 30 June 2014 | 5:59 pm

Metabolomics: What You See is What You Extract

Posted on 17 June 2014 | 8:05 am

A Universal Quantitative 1H Nuclear Magnetic Resonance (qNMR) Method for Assessing the Purity of Dammarane-type Ginsenosides

IntroductionQuantitative 1H-NMR (qNMR) is a well-established method for quantitative analysis and purity tests. Applications have been reported in many areas, such as natural products, foods and beverages, metabolites, pharmaceuticals and agriculture. The characteristics of quantitative estimation without relying on special target reference substances make qNMR especially suitable for purity tests of chemical compounds and natural products. Ginsenosides are a special group of natural products drawing broad attention, and are considered to be the main bioactive principles behind the claims of ginsengs efficacy. The purity of ginsenosides is usually determined by conventional chromatographic methods, although these may not be ideal due to the response of detectors to discriminate between analytes and impurities and the long run times involved. ObjectiveTo establish a qNMR method for purity tests of six dammarane-type ginsenoside standards. MethodsSeveral experimental parameters were optimised for the quantification, including relaxation delay (D1), the transmitter frequency offset (O1P) and power level for pre-saturation (PL9). The method was validated and the purity of the six ginsenoside standards was tested. Also, the results of the qNMR method were further validated by comparison with those of high performance liquid chromatography. ConclusionThe qNMR method was rapid, specific and accurate, thus providing a practical and reliable protocol for the purity analysis of ginsenoside standards. Copyright © 2014 John Wiley & Sons, Ltd.

Posted on 9 June 2014 | 8:07 pm

A Rapid Extraction and Analysis Method for the Simultaneous Determination of 26 Bioflavonoids in Portulaca Oleracea L.

IntroductionPortulaca oleracea L. (P. oleracea, purslane) is an edible plant that is widely distributed around the world, and flavonoids are its main bioactive constituents. Therefore, the detection of flavonoids is very important for a better understanding of its pharmacological actions and to monitor the product quality control of P. oleracea. ObjectiveTo develop a rapid method to extract and determine 26 bioflavonoids in P. oleracea, based on microwave extraction (MWE) and triple quadrupole-linear ion trap mass spectrometry. MethodsThe optimal conditions of MWE for the extraction of flavonoids from P. oleracea involved the use of methanol as the extraction solvent, a microwave power of 300 W, an extraction time of 450 s, and a solvent-to-solid ratio of 30 mL/g. The samples were analysed using an ultra-performance liquid chromatograph coupled with a triple quadrupole-linear ion trap mass spectrometer (UPLC–MS/MS) system. ResultsThe calibration curves of all 26 analytes showed good linearity (r ? 0.999) and the intra- and interday precisions and repeatability were all within required limits. The mean recoveries measured at three concentrations were higher than 94.2%, with RSDs lower than 2.94% for the targets. ConclusionThe established MWE/UPLC–MS/MS method is a rapid and effective method for quality evaluation of P. oleracea from different production regions and different harvest periods. Copyright © 2014 John Wiley & Sons, Ltd.

Posted on 29 May 2014 | 4:55 pm

Phenolic Compounds Involved in Grafting Incompatibility of Vitis spp: Development and Validation of an Analytical Method for their Quantification

Introduction Graft incompatibility of Vitis spp is an unresolved worldwide problem with important economic consequences. Grafting comprises a complex set of morphological and physiological alterations, in which the phenolic compounds seem to be strongly involved. Therefore, a detailed analysis and recognition of structural phenolic compounds diversity in the two partners of a Vitis graft is of great importance to evaluate their role as markers of graft establishment. Objective To optimise a sample extraction method, and to develop and validate a high-performance liquid chromatography (HPLC) method for the simultaneous determination of phenolic acids and flavonols in the graft union so as to understand their behaviour in the metabolism of the scion–rootstock system, using compatible and incompatible combinations of a Syrah cultivar and two rootstocks (R110 and SO4). Methods Sixty extracts of Vitis grafting tissues were prepared and analysed by HPLC for the qualitative and quantitative determination of their phenolic profile. Results Among the phenolic compounds identified in the samples, one benzoic acid (gallic acid), three cinnamic acids (caffeic acid, ferulic acid and sinapic acid) and two flavonols (catechin and epicatechin) are potentially suitable as markers of graft incompatibility. Conclusion The method developed presents good performance and lends itself readily for application in routine analysis of the phenolic composition of Vitis grafting tissues to distinguish compatible and incompatible combinations in the graft callusing stage. Copyright © 2014 John Wiley & Sons, Ltd.

Posted on 29 May 2014 | 4:55 pm

Evaluation of Salacia Species as Anti-diabetic Natural Resources Based on Quantitative Analysis of Eight Sulphonium Constituents: A New Class of ?-Glucosidase Inhibitors

Introduction Stems and roots of Salacia genus plants have been used in Ayurveda as a specific remedy for early stage diabetes. Previous investigations identified four sulphonium sulphates, that is, salacinol (1), kotalanol (3), ponkoranol (5) and salaprinol (7), as the compounds responsible for the anti-diabetic activity. Their desulphonates (2, 4, 6 and 8) were also isolated as active constituents. Two separate quantitative analytical protocols, that is, for 1 and 3 and for 2 and 4, have been developed recently. Objective To: validate the two analytical protocols with respect to all eight sulphoniums; evaluate the quality of a variety of Salacia samples collected in different geographical regions, that is, Thailand, Sri Lanka and India; and determine their distribution in each part of the plant, that is, stems/roots, leaves and fruits. Methods Analyses of four sulphonium sulphates in 32 Salacia extracts were carried out on an Asahipak NH2P-50 column, and those of the corresponding desulphonates were conducted on an Inertsil ODS-3 column. Results Neokotalanol (4) was the major constituent in Salacia samples from Thailand, whereas 1 was the primary constituent in extracts of the stems/roots of plants from Sri Lanka and India. These sulphoniums were only present in trace amounts in leaves and fruits of the plants. Conclusion Two analytical protocols were successfully applied to analyse 32 Salacia samples, and revealed that sulphoniums (1–8) had characteristic distributions due to the plant part and/or due to geographical region. Copyright © 2014 John Wiley & Sons, Ltd.

Posted on 9 May 2014 | 5:08 pm

Semi-automated Separation of the Epimeric Dehydropyrrolizidine Alkaloids Lycopsamine and Intermedine: Preparation of their N-oxides and NMR Comparison with Diastereoisomeric Rinderine and Echinatine

Introduction The diversity of structure and, particularly, stereochemical variation of the dehydropyrrolizidine alkaloids can present challenges for analysis and the isolation of pure compounds for the preparation of analytical standards and for toxicology studies. Objective To investigate methods for the separation of gram-scale quantities of the epimeric dehydropyrrolizidine alkaloids lycopsamine and intermedine and to compare their NMR spectroscopic data with those of their heliotridine-based analogues echinatine and rinderine. Methods Lycopsamine and intermedine were extracted, predominantly as their N-oxides and along with their acetylated derivatives, from commercial samples of comfrey (Symphytum officinale) root. Alkaloid enrichment involved liquid–liquid partitioning of the crude methanol extract between dilute aqueous acid and n-butanol, reduction of N-oxides and subsequent continuous liquid–liquid extraction of free base alkaloids into CHCl3. The alkaloid-rich fraction was further subjected to semi-automated flash chromatography using boronated soda glass beads or boronated quartz sand. Results Boronated soda glass beads (or quartz sand) chromatography adapted to a Biotage Isolera Flash Chromatography System enabled large-scale separation (at least up to 1–2 g quantities) of lycopsamine and intermedine. The structures were confirmed using one- and two-dimensional 1H- and 13C-NMR spectroscopy. Examination of the NMR data for lycopsamine, intermedine and their heliotridine-based analogues echinatine and rinderine allowed for some amendments of literature data and provided useful comparisons for determining relative configurations in monoester dehydropyrrolizidine alkaloids. A similar NMR comparison of lycopsamine and intermedine with their N-oxides showed the effects of N-oxidation on some key chemical shifts. A levorotatory shift in specific rotation from +3.29° to ?1.5° was observed for lycopsamine when dissolved in ethanol or methanol respectively. Conclusion A semi-automated flash chromatographic process using boronated soda glass beads was standardised and confirmed as a useful, larger scale preparative approach for separating the epimers lycopsamine and intermedine. The useful NMR correlations to stereochemical arrangements within this specific class of dehydropyrrolizidine alkaloid cannot be confidently extrapolated to other similar dehydropyrrolizidine alkaloids. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.

Posted on 9 May 2014 | 5:06 pm

Rapid Chemical Characterisation of Stilbenes in the Root Bark of Norway Spruce by Off-line HPLC/DAD–NMR

Introduction Stilbenes are plant secondary metabolites that have shown promising and varied biological activities. Stilbenes are presently actively studied for the exploitation of this primary raw material resource, involving the concept of biorefining. Methods for the rapid discovery of new and known stilbene structures from various plant sources are thus keenly sought. Objective To establish a simple and rapid technique of off-line HPLC with a diode-array detector (DAD) and NMR for the unambiguous structural elucidation of stilbene structures in the root bark of Norway spruce [Picea abies (L.) Karst.]. Material and methods The stilbene containing fraction was extracted from the plant bark with an ethanol:water mixture (95:5, v/v) preceded by defatting of hydrophobic compounds with n-hexane using the accelerated solvent extraction technique. A portion of the ethanol–water soluble extract was hydrolysed with ?-glucosidase to prepare stilbene aglycones. The extracts were further purified and enriched using a polymeric adsorbent. Stilbene-enriched extracts were directly characterised by off-line HPLC/DAD–NMR in conjunction with HPLC/DAD and HPLC/DAD with electrospray ionisation MSn. Results Trans-isorhapontin and trans-astringin were identified as the major, and trans-piceid as a minor, stilbene glucosides of the bark of roots of Picea abies. Not only stilbene glucosides but also the corresponding stilbene aglycones, such as trans-resveratrol, trans-piceatannol and trans-isorhapontigenin, were rapidly identified from the hydrolysed extract. The acquired heteronuclear single-quantum coherence and heteronuclear multiple bond correlation spectra were used to assign the complete carbon NMR chemical shifts of trans-isorhapontin and trans-astringin without the need of acquiring a 13C-NMR spectrum. Conclusion The off-line HPLC/DAD–NMR method is expedient for the unambiguous identication of structurally similar stilbenes in plant extracts. Copyright © 2014 John Wiley & Sons, Ltd.

Posted on 28 April 2014 | 2:48 pm

Liquid Chromatography–Mass Spectrometry and Chemometric Analysis of Ricinus communis Extracts for Cultivar Identification

Introduction Seeds of Ricinus communis contain the toxic protein ricin, a 64 kD heterodimeric type II ribosome-inactivating protein that has been used in several high-profile poisoning incidents. The ability to determine which cultivar the toxin was isolated from via an LC–MS method would be of significant use to law enforcement and forensic agencies. Objective To analyse via LC–MS and chemometrics (principal components analysis (PCA), orthogonal partial-least-squares discriminant analysis (OPLS-DA)) extracts of R. communis to identify compounds specific to a particular cultivar. Methods Seeds from eight specimens of six cultivars of R. communis (‘carmencita’, ‘dehradun’, ‘gibsonii’, ‘impala’, ‘sanguineus’ and ‘zanzibariensis’) were extracted using a standard methodology. These extracts were analysed by LC–MS then subjected to chemometric analysis (PCA and OPLS-DA). Identified compounds of importance were subjected to high-resolution Fourier transform (HRFT) MS and MS/MS to elucidate their structures. Results This analysis identified 17 ions as potential cultivar determinators. Through accurate mass measurement and MS/MS, molecular formulae for 13 ions were determined, including two known and 11 new peptides. Conclusion Unique ions in extracts of ‘carmencita’, ‘dehradun’, ‘gibsonii’, ‘impala’ and ‘zanzibariensis’ were identified that would allow an individual cultivar to be distinguished from other cultivars in this study. Although ‘sanguineus’ extracts contained no unique compounds, a unique LC–MS profile would allow for cultivar assignment. Copyright © 2014 John Wiley & Sons, Ltd.

Posted on 16 April 2014 | 7:32 am

A Comparative Tissue-specific Metabolite Analysis and Determination of Protodioscin Content in Asparagus Species used in Traditional Chinese Medicine and Ayurveda by use of Laser Microdissection, UHPLC–QTOF/MS and LC–MS/MS

Introduction Asparagus is esteemed in Traditional Chinese Medicine and Ayurveda, and it is commercially one of the most important drugs in the global herbal market. Comparative metabolite profiling of different species would help in determining the similarities and ascertain their validity for being used as substitutes for each other. Laser microdissection (LMD) facilitates identification of metabolites in specific tissues, and thus it can aid in exploration of metabolic pathways in target tissues. Objective To compare tissue-specific metabolites and protodioscin content of Asparagus cochinchinensis (Lour.) Merr. and Asparagus racemosus Willd. used in China and India. Methods Metabolite analysis of laser-dissected tissues was carried out using UHPLC–QTOF/MS and LC–MS/MS. The protodioscin contents were determined and the method was validated as per the International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use guidelines. Results Metabolite analysis reveals that the velamen tissue, among other tissues such as cortex, vascular bundles and pith, contained maximum components, specifically those belonging to the steroidal saponin class. Although the metabolite profiles were similar, the content of protodioscin was found to be higher in Chinese than Indian species. Conclusion The study provided a suitable methodology for metabolite profiling and protodioscin content determination of Asparagus by use of LMD, UHPLC–QTOF/MS and LC–MS/MS. The similarities in metabolite profiles indicate that Asparagus species from India and China can serve as substitute for each other in various therapeutic and pharmaceutical applications. Copyright © 2014 John Wiley & Sons, Ltd.

Posted on 16 April 2014 | 7:32 am

Identification and Quantitation of Phenolic Compounds from the Seed and Pomace of Perilla frutescens Using HPLC/PDA and HPLC–ESI/QTOF/MS/MS

Introduction Perilla frutescens (L.) Britt., an essential traditional Asian crop and Chinese medicine, potentially exerts anti-oxidation effects through its phenolic compounds. These compounds have already been reported in perilla seed, however, little is reported in Perilla pomace, the primary waste during oil production of Perilla seed. Objective To investigate major phenolic compounds in perilla seeds and pomaces in order to check whether the pomace could be an alternative resource to the seed for nutritional and medical purposes. Methods Compounds in extracts of perilla seeds and pomaces were separated by high-performance liquid chromatography and detected by photodiode array, and by electrospray ionisation with quadrupole time-of-flight tandem mass spectrometry. Herb-markers selected by principal components analysis were then quantified in both seeds and pomaces. Moreover, a fingerprinting approach and multiple discriminant analysis were applied to screen the phenolic markers in 22 samples. Results Ten phenols were tentatively identified, among which four (rosmarinic acid, luteolin, apigenin and rosmarinic acid-3-O-glucoside) were selected as herb-markers. Perilla seeds and pomaces showed similar phenol profiles, however, the pomaces contained almost two times the amount of the four herb-markers than the seeds. Conclusion The results indicated perilla pomace is a promising alternative source of phenolic compounds that could be recovered and potentially used as natural anti-oxidants. Copyright © 2014 John Wiley & Sons, Ltd.

Posted on 16 April 2014 | 7:32 am

NoSQL Data Model for Semi-automatic Integration of Ethnomedicinal Plant Data from Multiple Sources

Introduction Sharing traditional knowledge with the scientific community could refine scientific approaches to phytochemical investigation and conservation of ethnomedicinal plants. As such, integration of traditional knowledge with scientific data using a single platform for sharing is greatly needed. However, ethnomedicinal data are available in heterogeneous formats, which depend on cultural aspects, survey methodology and focus of the study. Phytochemical and bioassay data are also available from many open sources in various standards and customised formats. Objective To design a flexible data model that could integrate both primary and curated ethnomedicinal plant data from multiple sources. Materials and methods The current model is based on MongoDB, one of the Not only Structured Query Language (NoSQL) databases. Although it does not contain schema, modifications were made so that the model could incorporate both standard and customised ethnomedicinal plant data format from different sources. Results The model presented can integrate both primary and secondary data related to ethnomedicinal plants. Accommodation of disparate data was accomplished by a feature of this database that supported a different set of fields for each document. It also allowed storage of similar data having different properties. Conclusion The model presented is scalable to a highly complex level with continuing maturation of the database, and is applicable for storing, retrieving and sharing ethnomedicinal plant data. It can also serve as a flexible alternative to a relational and normalised database. Copyright © 2014 John Wiley & Sons, Ltd.

Posted on 16 April 2014 | 7:32 am

Ultra-performance LC Separation and Quadrupole Time-of-flight MS Identification of Major Alkaloids in Plumula Nelumbinis

Introduction As an essential medicine and tea source in many countries, Plumula Nelumbinis potentially exerts its major biological activities through its alkaloids. However, the activities of Plumula Nelumbinis are not fully understood due to the lack of studies on its chemical components. Objective To establish an ultra-performance liquid chromatography combined with diode-array detector (UPLC/DAD) method, coupled to an electrospray ionisation with quadrupole time-of-flight mass spectrometry (ESI/QTOF/MS) method, for the separation and identification of Plumula Nelumbinis alkaloids. Methods The eluant from an UPLC separation of an ethanol extract of Plumula Nelumbinis was directly infused into an ESI/QTOF/MS system. Both positive and negative ion modes of ESI with low and high collision energy (CE) were used to obtain sufficient MS information. Results Twenty-one alkaloids were tentatively identified based on their chromatographic characteristics, UV spectra, exact mass, MS fragments and literature reports. They consist of six bis-1-benzyltetrahydroisoquinoline, eleven benzyltetrahydroisoquinoline (including two glycoalkaloids and two quaternary ammoniums), two aporphine, one proaporphine and one indole alkaloids. Eleven were identified in Plumula Nelumbinis for the first time and seven were first reported in Nelumbo nucifera Gaertn. Five compounds, namely norcoclaurine-4?-O-glucoside, norcoclaurine-6-O-glucoside, isolotusine, 6-demethyl-4-demethylN-methylcoclaurine and N-norisoliensinine, were characterised and proposed as new compounds. Conclusion The established UPLC/DAD???ESI/QTOF/MS method is efficient for systematic identification of the alkaloids in Plumula Nelumbinis extract. Copyright © 2014 John Wiley & Sons, Ltd.

Posted on 15 April 2014 | 1:26 am

Evaluation of Anti-oxidant and Acetylcholinesterase Activity and Identification of Polyphenolics of the Invasive Weed Dittrichia viscosa

Introduction The bioactive metabolites derived from weeds have attracted the interest of the food and pharmaceutical industries due to their health benefits. Objective To evaluate the anti-oxidant and acetylcholinesterase activity of Dittrichia viscosa extracts and characterise the polyphenolic metabolites using the LC coupled with diode-array detection (DAD) and positive mode electrospray ionisation (ESI) MS method with a view to evaluating the exploitation potential of this invasive weed. Materials and methods Roots and aerial parts of D. viscosa were extracted with solvents of increasing polarity and their major polyphenolic metabolites were identified by LC???DAD/ESI(+)/MS. The total phenolic content of the extracts was determined using the Folin–Ciocalteu method, while their anti-oxidant activity was evaluated on the basis of their ability to scavenge the stable free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH) and hydrogen peroxide. Thin-layer chromatography was used to screen for acetylcholinesterase inhibitors. Results Stem extracts gave the highest phenolic content, whereas the roots showed the lowest content. Twenty-five polyphenolic constituents of the extracts were tentatively characterised according to their MS and UV spectroscopic data. Among the extracts studied, roots–ethyl acetate and flowers–diethyl ether revealed the highest activity according to the DPPH and chemiluminescence assays respectively. Conclusion The metabolic profile of D. viscosa was studied and the structures of the major polyphenolic metabolites were tentatively assigned based on their MS and UV–vis spectra. The extracts exhibited high levels of anti-oxidant and acetylcholinesterase inhibitory activity and the inhibitors are probably localised mainly in flowers and roots. Copyright © 2014 John Wiley & Sons, Ltd.

Posted on 14 April 2014 | 5:01 pm

Optimisation of the Microplate Resazurin Assay for Screening and Bioassay-guided Fractionation of Phytochemical Extracts against Mycobacterium tuberculosis

Introduction Because of increased resistance to current drugs, there is an urgent need to discover new anti-mycobacterial compounds for the development of novel anti-tuberculosis drugs. The microplate resazurin assay (MRA) is commonly used to evaluate natural products and synthetic compounds for anti-mycobacterial activity. However, the assay can be problematic and unreliable when screening methanolic phytochemical extracts. Objective To optimise the MRA for the screening and bioassay-guided fractionation of phytochemical extracts using Mycobacterium tuberculosis H37Ra. Methods The effects of varying assay duration, resazurin solution composition, solvent (dimethyl sulphoxide – DMSO) concentration and type of microtitre plate used on the results and reliability of the MRA were investigated. The optimal bioassay protocol was applied to methanolic extracts of medicinal plants that have been reported to possess anti-mycobacterial activity. Results The variables investigated were found to have significant effects on the results obtained with the MRA. A standardised procedure that can reliably quantify anti-mycobacterial activity of phytochemical extracts in as little as 48 h was identified. The optimised MRA uses 2% aqueous DMSO, with an indicator solution of 62.5 µg/mL resazurin in 5% aqueous Tween 80 over 96 h incubation. Conclusion The study has identified an optimal procedure for the MRA when used with M. tuberculosis H37Ra that gives rapid, reliable and consistent results. The assay procedure has been used successfully for the screening and bioassay-guided fractionation of anti-mycobacterial compounds from methanol extracts of Canadian medicinal plants. Copyright © 2014 John Wiley & Sons, Ltd.

Posted on 14 April 2014 | 5:01 pm

Piper betle Leaves: Profiling Phenolic Compounds by HPLC/DAD–ESI/MSn and Anti-cholinesterase Activity

Introduction Piper betle L. is a widely distributed plant in the tropical and subtropical regions, its leaves being largely consumed as a masticator and mouth freshener. Objective The purposes of this work were to characterise the phenolic profile of this species and to improve knowledge of its anti-cholinesterase properties. Methods The phenolic composition of P. betle leaf aqueous and ethanol extracts was characterised by HPLC coupled with a diode-array detector and combined with electrospray ionisation tandem MS, and in vitro cholinesterase inhibitory capacity of both extracts was assessed by spectrophotometric microassays. The effect on neuronal cells (SH-SY5Y) viability was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide reduction and lactate dehydrogenase leakage. Results Twelve phenolic compounds, comprising a phenylpropanoid, five cinnamoyl and six flavonoids derivatives were identified in P. betle leaves. Hydroxychavicol was the major compound in both extracts; however, the aqueous extract presented a greater diversity of compounds. Both extracts showed strong activity against both acetyl- and butyrylcholinesterase, which can be due, at least partially, to the phenolic composition. Furthermore, the aqueous extract proved to be cytotoxic to human neuroblastoma cells at concentrations higher than 500?µg/mL. Conclusion The results suggest that the consumption of P. betle leaves as an infusion can have a positive impact in the prevention and treatment of neurodegenerative diseases. Apigenin and luteolin derivatives are reported for the first time in this species. Copyright © 2014 John Wiley & Sons, Ltd.

Posted on 14 April 2014 | 5:01 pm

Microplate Quantification of Total Phenolic Content from Plant Extracts Obtained by Conventional and Ultrasound Methods

Introduction There is increasing interest in phenolic compounds around the world because of their potential positive impact on human health. Phenolic compounds are largely found in fruits and vegetables. Extraction of phenolic compounds is a very important step in their recovery. The newly developed technique of ultrasound-assisted extraction (UAE) appears to be an advantageous alternative compared with conventional techniques, because it is simple and environmental friendly. The potential of UAE needs to be evaluated in each plant in order to demonstrate its efficiency. Objective The objective of the present study was to compare a conventional method and UAE on the extraction efficiency of phenolic compounds from Jatropha dioica, Fluorensia cernua, Turnera diffusa and Eucalyptus camaldulensis plants and evaluate the in vitro anti-oxidant potential. Methods Validation of the new method was carried out using mixed-model methodology and regression analysis. Feasibility of this new method was shown and applied using several plants extracts obtained by different extraction methods from semi-arid Mexican plants, which were characterised by high levels of polyphenols. Additionally, the anti-oxidant potential of these extracts was determined by 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity. Results Results showed that the new microplate method can be used to determine total phenolic content in plant extracts. Additionally, an alternative extraction method by ultrasound was less efficient compared with the conventional method. Conclusion The tested plants are good candidates to obtain nutraceuticals and functional food ingredients. Copyright © 2014 John Wiley & Sons, Ltd.

Posted on 1 April 2014 | 4:20 pm

Near-infrared Reflectance Spectroscopy as a Rapid and Non-destructive Analysis Tool for Curcuminoids in Turmeric

Introduction Turmeric has been widely used in curry powders as the main spice. Conventional chemical analysis such as high-performance liquid chromatography (HPLC) may take several hours to extract curcuminoids and prepare samples in many turmeric processing industries. Objective This study was conducted to evaluate curcuminoids in turmeric powder using near-infrared reflectance spectroscopy (NIRS). Methods All spectral acquisition ranged from 1100 to 2500 nm and a chemometrics analysis using partial least-squares (PLS) regression was performed to quantify the contents of individual curcuminoids. The HPLC was carried out (n = 129) to develop a PLS model based on the reference values. Results High correlation coefficient (R2 > 0.93) and low standard error of cross-validation (SECV < 0.20 g/100 g) and standard error of prediction (SEP < 0.13 g/100 g) values were obtained for precision and accuracy. In addition, the ratio of prediction to deviation (RPD > 2.65) values was also calculated. Conclusion Our results indicate that NIRS could be utilised as a control procedure or as an alternative rapid and effective quantification method. Copyright © 2014 John Wiley & Sons, Ltd.

Posted on 1 April 2014 | 4:03 pm

Monodimensional (GC–FID and GC–MS) and Comprehensive Two-dimensional Gas Chromatography for the Assessment of Volatiles and Fatty Acids from Ruta chalepensis Aerial Parts

Introduction Ruta chalepensis L. (Rutaceae) is widespread in the Mediterranean area. This plant has a solid tradition in ethnomedicine because of its various biological activities. Based on previous reports, the main volatile constituents of R. chalepensis are 2-undecanone and 2-nonanone, but most are still unknown, particularly fatty acid composition. Objective To exhaustively characterise the chemical composition of the aerial parts from R. chalepensis plants collected from the wild in Sicily, within a project aiming at the evaluation and characterisation of medicinal plants from the Mediterranean flora. The study was directed toward the determination of volatiles and fatty acids in samples of R. chalepensis obtained from different aerial plant parts and from plants harvested at different times. Methods GC with flame ionisation detection, GC–MS and two-dimensional gas chromatography (GC?×?GC) advanced techniques, with support of dedicated mass spectral databases provided with retention index (RI) information, were applied to determine both volatiles and fatty acids. Samples were extracted by hydrodistillation and underwent methylic transesterification in order to be transformed into the correspondent fatty acid methyl esters (FAMEs). Results The monodimensional analysis by GC–MS with RI confirmed that 2-nonanone and 2-undecanone are the predominant components in all the plant parts, followed by esters and monoterpenes. A different distribution was observed of the main compounds in the various plant parts depending on the life cycle of the plant (vegetative or reproductive stage). The multidimensional GC?×?GC analysis allowed for a complete screening of the fatty acids. About 65% of the total were polyunsaturated fatty acids (PUFA), followed by 30% of saturated fatty acids (SFA). Conclusion A detailed GC volatile fingerprint of R. chalepensis flowers, leaves, fruits and stems was established, highlighting the compositional differences depending on plant organs and life cycle. The results indicated R. chalepensis as a good source of fatty acids from the w3 and w6 series. In both essential oil and lipidic extract, many compounds were determined for the first time. Copyright © 2014 John Wiley & Sons, Ltd.

Posted on 1 April 2014 | 4:03 pm

Extraction for Metabolomics: Access to The Metabolome

IntroductionThe value of information obtained from a metabolomic study depends on how much of the metabolome is present in analysed samples. Thus, only a comprehensive and reproducible extraction method will provide reliable data because the metabolites that will be measured are those that were extracted and all conclusions will be built around this information. ObjectiveTo discuss the efficiency and reliability of available sample pre-treatment methods and their application in different fields of metabolomics. MethodsThe review has three sections: the first deals with pre-extraction techniques, the second discusses the choice of extraction solvents and their main features and the third includes a brief description of the most used extraction techniques: microwave-assisted extraction, solid-phase extraction, supercritical fluid extraction, Soxhlet and a new method developed in our laboratory – the comprehensive extraction method. ResultsExamination of over 200 studies showed that sample collection, homogenisation, grinding and storage could affect the yield and reproducibility of results. They also revealed that apart from the solvent used for extraction, the extraction techniques have a decisive role on the metabolites available for analysis. ConclusionIt is essential to evaluate efficacy and reproducibility of sample pre-treatment as a first step to ensure the reliability of a metabolomic study. Among the reviewed methods, the comprehensive extraction method appears to provide a promising approach for extracting diverse types of metabolites. Copyright © 2014 John Wiley & Sons, Ltd.

Posted on 13 February 2014 | 7:22 am

Sample Preparation Issues in NMR-based Plant Metabolomics: Optimisation for Vitis Wood Samples

IntroductionNuclear magnetic resonance (NMR) is one of the most commonly used analytical techniques in plant metabolomics. Although this technique is very reproducible and simple to implement, sample preparation procedures have a great impact on the quality of the metabolomics data. ObjectiveInvestigation of different sample preparation methods and establishment of an optimised protocol for untargeted NMR-based metabolomics of Vitis vinifera L. wood samples. MethodsWood samples from two different cultivars of V. vinifera with well-defined phenotypes (Gamaret and 2091) were selected as reference materials. Different extraction solvents (successively, dichloromethane, methanol and water, as well as ethyl acetate and 7:3 methanol-water (v/v)) and deuterated solvents (methanol-d4, 7:3 chloroform-d-methanol-d4 (v/v), dimethylsulphoxide-d6 and 9:1 dimethylsulphoxide-d6-water-d2 (v/v)) were evaluated for NMR acquisition, and the spectral quality was compared. The optimal extract concentration, chemical shift stability and peak area repeatability were also investigated. ResultsEthyl acetate was found to be the most satisfactory solvent for the extraction of all representative chemical classes of secondary metabolites in V. vinifera wood. The optimal concentration of dried extract was 10 mg/mL and 7:3 chloroform-d-methanol-d4 (v/v) was the most suitable solvent system for NMR analysis. Multivariate data analysis was used to estimate the biological variation and clustering between different cultivars. ConclusionClose attention should be paid to all required procedures before NMR analysis, especially to the selection of an extraction solvent and a deuterated solvent system to perform an extensive metabolomic survey of the specific matrix. Copyright © 2014 John Wiley & Sons, Ltd.

Posted on 4 February 2014 | 1:29 pm

An Easy, Convenient Cell and Tissue Extraction Protocol for Nuclear Magnetic Resonance Metabolomics

IntroductionAs a complement to the classic metabolomics biofluid studies, the visualisation of the metabolites contained in cells or tissues could be a very powerful tool to understand how the local metabolism and biochemical pathways could be affected by external or internal stimuli or pathologies. Therefore, extraction and/or lysis is necessary to obtain samples adapted for use with the current analytical tools (liquid NMR and MS). These extraction or lysis work-ups are often the most labour-intensive and rate-limiting steps in metabolomics, as they require accuracy and repeatability as well as robustness. Many of the procedures described in the literature appear to be very time-consuming and not easily amenable to automation. ObjectiveTo find a fast, simplified procedure that allows release of the metabolites from cells and tissues in a way that is compatible with NMR analysis. MethodsWe assessed the use of sonication to disrupt cell membranes or tissue structures. Both a vibrating probe and an automated bath sonicator were explored. ResultsThe application of sonication as the disruption procedure led to reproducible NMR spectral data compatible with metabolomics studies. This method requires only a small biological tissue or cell sample, and a rapid, reduced work-up was applied before analysis. The spectral patterns obtained are comparable with previous, well-described extraction protocols. ConclusionThe rapidity and the simplicity of this approach could represent a suitable alternative to the other protocols. Additionally, this approach could be favourable for high- throughput applications in intracellular and intratissular metabolite measurements. Copyright © 2014 John Wiley & Sons, Ltd.

Posted on 23 January 2014 | 11:33 am

An Overview of Plant Volatile Metabolomics, Sample Treatment and Reporting Considerations with Emphasis on Mechanical Damage and Biological Control of Weeds

IntroductionThe technology for the collection and analysis of plant-emitted volatiles for understanding chemical cues of plant–plant, plant–insect or plant–microbe interactions has increased over the years. Consequently, the in situ collection, analysis and identification of volatiles are considered integral to elucidation of complex plant communications. Due to the complexity and range of emissions the conditions for consistent emission of volatiles are difficult to standardise. ObjectiveTo discuss: evaluation of emitted volatile metabolites as a means of screening potential target- and non-target weeds/plants for insect biological control agents; plant volatile metabolomics to analyse resultant data; importance of considering volatiles from damaged plants; and use of a database for reporting experimental conditions and results. MethodRecent literature relating to plant volatiles and plant volatile metabolomics are summarised to provide a basic understanding of how metabolomics can be applied to the study of plant volatiles. ResultsAn overview of plant secondary metabolites, plant volatile metabolomics, analysis of plant volatile metabolomics data and the subsequent input into a database, the roles of plant volatiles, volatile emission as a function of treatment, and the application of plant volatile metabolomics to biological control of invasive weeds. ConclusionIt is recommended that in addition to a non-damaged treatment, plants be damaged prior to collecting volatiles to provide the greatest diversity of odours. For the model system provided, optimal volatile emission occurred when the leaf was punctured with a needle. Results stored in a database should include basic environmental conditions or treatments. Copyright © 2013 John Wiley & Sons, Ltd.

Posted on 18 December 2013 | 11:30 am

Extraction-free In situ Derivatisation of Timosaponin AIII Using Direct Analysis in Real Time TOF/MS

IntroductionDirect analysis in real time (DART) TOF/MS has been used for mass information of various non-polar phytochemicals in raw material with no sample preparation. However, low ionisation efficiency for polar compounds including glycosides limits its extensive use in the field of phytochemical analysis. ObjectiveIn order to develop a direct analysis method for polar glycosides using in situ derivatisation, which improves ionisation efficiency of hydrophilic glycosides. MethodAnemarrhena Rhizoma was used as a model plant targeting on Timosaponin AIII utilising a Dip-It module. Permethylation was applied to the powdered raw material with tetramethylammonium hydroxide in front of a DART ion source. Also, DART TOF/MS combined with permethylation was applied to timosaponin AIII standard solution to obtain the limit of detection (LOD). ResultsIn situ methylation of timosaponin AIII and Anemarrhena Rhizoma raw material were successfully used to ionise the glycoside. The LOD was found to be in the range of 2.4–4.8 ng for permethylated timosaponin AIII and this level is four times higher than the range of the underivatisation analysis. Direct analysis of permethylated timosaponin from Anemarrhena Rhizoma was also successfully performed. ConclusionA simple and quick derivatisation method with tetramethylammonium hydroxide was developed for the direct identification of a hydrophilic saponin from the plant tissue. Better ionisation efficiency conferred by in situ permethylation enabled ionisation of whole molecules of timosaponin AIII from the plant tissue. This simple analytical method will provide a solution to reduce tedious sample preparation steps, not only for non-polar but also hydrophilic natural products directly from the tissue. Copyright © 2013 John Wiley & Sons, Ltd.

Posted on 5 December 2013 | 9:26 am

Sample Preparation for Liquid Chromatographic Analysis of Phytochemicals in Biological Fluids

IntroductionNatural products have been used traditionally for the treatment and prevention of diseases for thousands of years and are nowadays consumed as dietary supplements and herbal medicine. To ensure the safe and effective use of these herbal products, information about bioavailability of active compounds in plasma or target tissues should be provided via validated analytical methods combined with appropriate sampling methods. ObjectiveTo provide comprehensive and abridged information about sample preparation methods for the quantification of phytochemicals in biological samples using liquid chromatography analysis. MethodsSample pre-treatment procedures used in analytical methods for in vivo pharmacokinetic studies of natural compounds or herbal medicines were reviewed. These were categorised according to the biological matrices (plasma, bile, urine, faeces and tissues) and sample clean-up processes (protein precipitation, liquid–liquid extraction and solid-phase extraction). ResultsAlthough various kinds of sample pre-treatment methods have been developed, liquid–liquid extraction is still widely used and solid-phase extraction is becoming increasingly popular because of its efficiency for extensive clean up of complex matrix samples. However, protein precipitation is still favoured due to its simplicity. ConclusionSample treatment for phytochemical analysis in biological fluids is an indispensable and critical step to obtain high quality results. This step could dominate the overall analytical process because both the duration of the process as well as the reliability of the data depend in large part on its efficiency. Thus, special attention should be given to the choice of a proper sample treatment method that targets analytes and their biomatrix. Copyright © 2013 John Wiley & Sons, Ltd.

Posted on 2 December 2013 | 3:33 pm

Efficiency of Different Solvents on the Extraction of Bioactive Compounds from the Amazonian Fruit Caryocar villosum and the Effect on its Antioxidant and Colour Properties

IntroductionCaryocar villosum has been reported as a source of bioactive compounds that can be used as a potential product against oxidative damage in foods or biological systems. ObjectiveTo obtain extracts from fruit pulps of C. villosum with high levels of bioactive compounds that have both antioxidant and colour properties. MethodThe contents of bioactive compounds (total phenolic compounds, flavonoids, tannins, carotenoids and tocopherols), the colour parameters, the scavenging capacity against peroxyl radicals (ROO•) and the quenching activity against singlet oxygen (1O2) were determined. All data were used for extract classification by applying principal components analysis and hierarchical cluster analysis. ResultsThe water and ethanol:water (1:1, v/v) extracts presented the highest levels of total phenolic compounds (9.2 and 6.3 mg gallic acid equivalent/g extract, respectively), total flavonoids (3.8 and 2.5 mg catechin equivalent/g extract, respectively) and total tannins (7.6 and 2.4 mg tannic acid equivalent/g extract, respectively). The ethanol:water (1:1, v/v) extract also showed the highest scavenging capacity against ROO• (0.3 mmol trolox equivalent/g extract) and the highest protection against 1O2 (12.5%). On the other hand, the ethanol extracts, which were the most vivid and yellow colour (C*ab?=?13.7 and b*?=?13.3), presented the highest level of total carotenoids (0.1 mg/g), but low scavenging capacity against ROO• (0.01 mmol trolox equivalent/g extract). ConclusionBased on these results and depending on the applicability, the ethanol:water, water and ethanol are the most promising solvents to obtain C. villosum extracts with high contents of bioactive compounds, ROO• scavenging capacity and protection against 1O2. Copyright © 2013 John Wiley & Sons, Ltd.

Posted on 26 November 2013 | 6:41 am

Species-specific Standardisation of Licorice by Metabolomic Profiling of Flavanones and Chalcones

IntroductionMajor phenolics from licorice roots (Glycyrrhiza sp.) are glycosides of the flavanone liquiritigenin (F) and its 2?-hydroxychalcone isomer, isoliquiritigenin (C). As the F and C contents fluctuate between batches of licorice, both quality control and standardisation of its preparations become complex tasks. ObjectiveTo characterise the F and C metabolome in extracts from Glycyrrhiza glabra L. and Glycyrrhiza uralensis Fisch. ex DC. by addressing their composition in major F–C pairs and defining the total F:C proportion. Material and methodsThree types of extracts from DNA-authenticated samples were analysed by a validated UHPLC/UV method to quantify major F and C glycosides. Each extract was characterised by the identity of major F–C pairs and the proportion of Fs among all quantified Fs:Cs. ResultsThe F and C compositions and proportions were found to be constant for all extracts from a Glycyrrhiza species. All G. uralensis extracts contained up to 2.5 more Fs than G. glabra extracts. Major F–C pairs were B-ring glycosidated in G. uralensis, and A-/B-ring apiosyl-glucosidated in the G. glabra extracts. The F:C proportion was found to be linked to the glycosidation site: the more B-ring F-C glycosides were present, the higher was the final F:C proportion in the extract. These results enable the chemical differentiation of extracts from G. uralensis and G. glabra, which are characterised by total F:C proportions of 8.37:1.63 and 7.18:2.82, respectively. ConclusionExtracts from G. glabra and G. uralensis can be differentiated by their respective F and C compositions and proportions, which are both useful for further standardisation of licorice botanicals. Copyright © 2013 John Wiley & Sons, Ltd.

Posted on 13 November 2013 | 10:29 am

Laser Microdissection: a Sample Preparation Technique for Plant Micrometabolic Profiling

IntroductionUnlike unicellular organisms, plants have evolved as complex organisms that are defined by their ability to distribute special vital functions to spatially separated organs and tissues. Current phytochemical approaches mostly ignore this fact by analysing samples that consist of different cell types and thus average the information obtained. A comprehensive metabolite analysis with high spatial resolution is essential to fully characterise the state of a certain tissue; hence, the analysis of metabolites occurring in specialised plant cells is of considerable interest in chemical ecology, plant natural product chemistry and other bioscience disciplines. Laser microdissection (LMD), including laser capture microdissection and laser microdissection and pressure catapulting, is a convenient sampling technique to harvest homogeneous cell types for the microanalysis of plant metabolites. ObjectiveThe objective of this work is to provide an introduction to LMD methodology and a concise review of recent applications of LMD in the high-resolution analysis of metabolites in different plant materials. MethodsA step-by-step approach to LMD sampling techniques is described. How LMD can be used to sample cells or microscopic tissue pieces from different plant organs, such as leaves, stems, and seeds, is shown in detail. Finally, the future of LMD in plant metabolites analysis is discussed. ResultsThis review summarises studies over the past decade not only showing technical details but also indicating the wide application of this method for high-resolution plant metabolite analysis. ConclusionLaser microdissection is a powerful sampling technique for plant micrometabolic profiling and metabolomics research. Copyright © 2013 John Wiley & Sons, Ltd.

Posted on 23 September 2013 | 7:12 pm

Ultrasound-assisted Extraction with LC–TOF/MS Identification and LC–UV Determination of Imazamox and its Metabolites in Leaves of Wheat Plants

Introductionimazamox is a herbicide used in many legominous and cereal crops. There are few methods in the literature for determination of imazamox and its metabolites in plants because of the lack of commercial standards or owing to expensive and/or complex synthesis. ObjectiveTo develop a method based on liquid chromatography and ultraviolet absorption detection for simultaneous determination of imazamox and its metabolites in plants. MethodsSample preparation was based on ultrasound-assisted extraction (70?W power and duty cycle of 0.7?s/s for 10?min) with subsequent filtration of the extracts and clean-up and concentration prior to chromatographic separation and detection at 240?nm. The chromatographic analysis was completed in 30?min using a Luna® HILIC column. Identification and confirmatory analysis of the presence of imazamox and its metabolites in extracts from treated plants was performed by LC–TOF/MS in high resolution mode for precursor ions. The metabolites were quantified using a surrogate approach based on an imazamox standard. The method was validated by analysing wheat samples treated with 200?g per hectare of active ingredient imazamox. ResultsThe linear dynamic range of the calibration curve was within 0.27–600?µg/mL, with a correlation coefficient of 0.998 and precision – studied at 0.1 and 2?µg/mL – of 2.9% and 5.0% for repeatability, and 4.7% and 6.9% for reproducibility, respectively. ConclusionThe analytical characteristics of the method make it recommendable for evaluating the metabolism of imazamox in plants. Copyright © 2013 John Wiley & Sons, Ltd.

Posted on 10 August 2013 | 7:27 am

Other notes:

 Information about this site:

The author- or copyrights of the listed Internet pages are held by the respective authors or site operators, who are also responsible for the content of the presentations.
To see your page listed here: Send us an eMail! Condition: Subject-related content on chemistry, biochemistry and comparable academic disciplines!
Chronological list of recent articles on Chemistry, Phytochemistry, Phytochemical Analysis.

Internetchemistry ChemLin © 1996 - 2013 A. J.