Unknown Compounds (unknown + compound)

Distribution by Scientific Domains


Selected Abstracts


Essential oil composition and antimicrobial activity of tuberous roots of Pimpinella tirupatiensis Bal.

FLAVOUR AND FRAGRANCE JOURNAL, Issue 6 2002
& Subr., India, an endemic taxon from eastern ghats
Abstract The tuberous roots of Pimpinella tirupatiensis (Apiaceae) were subjected to sequential extraction with different polar solvents and the extracts were tested against eight bacterial and three fungal pathogenic strains for antimicrobial activity. The minimum inhibitory concentration of active extracts against six bacterial and two fungal strains were determined. The hexane and ethyl acetate fractions exhibited a broad spectrum of antimicrobial activity and were analysed for different phytochemicals. The active extracts contained significant amounts of alkaloids, flavonols, flavones and volatile oils. The hexane extract yielded an essential oil when subjected to GC with FID. The compounds were identified based on their retention indices and yielded 24 known compounds and one unknown compound. The major compounds are ,-bisabolene (9.2%), ,-3-carene (8.9%), cis -carveol (6.7%), elemol (5.8%), ,-cadinol (4.4%), methyl geranate (4.3%) and ,-nonalactone (3.4%). Copyright 2002 John Wiley & Sons, Ltd. [source]


5,-Deoxyisopentenyladenosine and other cytokinins in culture filtrates of the bacterium Pantoea agglomerans

PHYSIOLOGIA PLANTARUM, Issue 3 2004
Zahra Saad Omer
A Pantoea agglomerans isolate from barley seeds, selected for inducing growth promotion in tomato test plants, was found to excrete several hormones of the cytokinin class into its culture medium. In addition to isopentenyladenine, isopentenyladenosine and the 2-methylthiol derivates of these, an unknown compound with affinity to anticytokinin antibodies was also isolated. Mass spectroscopy indicated the structure of this to be a deoxyisopentenyladenosine. The structure of 9-(5,-deoxy- , - d -ribofuranosyl)-6-(3-methyl-2-butenylamino)purine was verified after synthesis of standards and analysis with GC,MS. The synthesized 5,-deoxyisopentenyl-adenosine showed activity in the Amaranthus bioassay, specific for cytokinins. To our knowledge this is the first report of a naturally occurring cytokinin containing 5,-deoxyribose. [source]


Diversity of essential oil glands of clary sage (Salvia sclarea L., Lamiaceae)

PLANT BIOLOGY, Issue 4 2008
C. Schmiderer
Abstract The Lamiaceae is rich in aromatic plant species. Most of these species produce and store essential oils in specialised epidermal oil glands, which are responsible for their specific flavour. Two types of glands producing essential oil and possessing different morphological structure can be found in Salvia sclarea: peltate and capitate glands. The content of single oil glands from different positions on the plant (corolla, calyx and leaf) were sampled using an SPME fibre and analysed by gas chromatography in order to study variability of the essential oil composition. It was found that the composition of terpenoids is quite variable within an individual plant. Capitate oil glands mainly produce three essential oil compounds: the monoterpenes linalool and linalyl acetate, and the diterpene sclareol. Peltate oil glands, however, accumulate noticeable concentrations of sesquiterpenes and an unknown compound (m/z = 354). Furthermore, the oil composition varies within each gland type according to the plant organ. Linalool and linalyl acetate are characteristic substances of flowers, whereas the sesquiterpenes occur in higher proportions in leaves. Even within one gland type on a single leaf, the chemical variability is exceedingly high. [source]


Liquid chromatography coupled to quadruple time-of-flight tandem mass spectrometry for microcystin analysis in freshwaters: method performances and characterisation of a novel variant of microcystin-RR

RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 9 2009
Pasquale Ferranti
Cyanobacteria, also called blue-green algae, occur worldwide within water blooms in eutrophic lakes and drinking water reservoirs, producing several biotoxins (cyanotoxins). Among these, microcystins (MCs) are a group of cyclic heptapeptides showing potent hepatotoxicity and activity as tumour promoters. So far, at least 89 MCs from different cyanobacteria genera have been characterised. Herein, ion trap, matrix-assisted laser desorption/ionisation time-of-flight (MALDI-ToF) and quadruple time-of-flight (Q-ToF) mass spectrometry (MS)-based methods were tested and compared for analysing MCs in freshwaters. Method performances in terms of limit of detection, limit of quantification, mean recoveries, repeatability, and specificity were evaluated. In particular, a liquid chromatography/electrospray ionisation (LC/ESI)-Q-ToF-MS/MS method was firstly described to analyse MCs in freshwaters; this technique is highly selective and sensitive, and allowed us to characterise the molecular structure of an unknown compound. Indeed, the full structural characterisation of a novel microcystin variant from a bloom of Planktothrixrubescens in the Lake Averno, near Naples, was attained by the study of the fragmentation pattern. The new cyanotoxin was identified as the 9-acetyl-Adda variant of microcystin-RR. Copyright 2009 John Wiley & Sons, Ltd. [source]


Comparison of three methods for the extraction of arsenic compounds from the NRCC standard reference material DORM-2 and the brown alga Hijiki fuziforme

APPLIED ORGANOMETALLIC CHEMISTRY, Issue 6 2001
Doris Kuehnelt
Abstract The NRCC standard reference material DORM-2 and the marine brown alga Hijiki fuziforme were extracted with water, methanol/water (9,+,1), and 1.5 M orthophosphoric acid. The extracts from DORM-2 were analyzed by HPLC,ICP-MS for arsenobetaine, arsenocholine, trimethylarsine oxide, and the tetramethylarsonium cation and the extracts from H. fuziforme for arsenous acid, arsenic acid, dimethylarsinic acid, methylarsonic acid, and four arsenoriboses. Almost no differences between the three extractants were observed when DORM-2 was investigated. Only arsenobetaine was slightly better extracted with 1.5 M orthophosphoric acid or methanol/water (9,+,1) than with water. The sum of all extractable compounds (arsenobetaine, the tetramethylarsonium cation, and a formerly unknown compound recently identified as the trimethyl(2-carboxyethyl)arsonium ion) accounted for 94% of the total arsenic when 1.5 M orthophosphoric acid was used, for 92% when methanol/water (9,+,1) was used, and for 87% when water was used. Significant differences in the extraction yields obtained for the alga were observed for arsenic acid and one of the arsenoriboses (,glycerol-ribose'). Orthophosphoric acid removed twice as much of this ribose from the algal material than water and three times more than methanol/water (9,+,1). Arsenic acid was 1.2 times better extracted with orthophosphoric acid than with water and ten times better than with methanol/water (9,+,1). Almost no differences in the extraction yields were found for dimethylarsinic acid and the other three riboses. Orthophosphoric acid extracted 76%, water 65%, and methanol/water 33% of the total arsenic from H. fuziforme. Copyright 2001 John Wiley & Sons, Ltd. [source]


Enzymatic stability of 2,-ethylcarbonate-linked paclitaxel in serum and conversion to paclitaxel by rabbit liver carboxylesterase for use in prodrug/enzyme therapy

BIOPHARMACEUTICS AND DRUG DISPOSITION, Issue 5 2008
Tadatoshi Tanino
Abstract In prodrug/enzyme therapy for cancer, information on the sensitivity of hydrolytic enzymes to prodrug is required to reduce adverse effects of the parental drug and to find the activating enzyme. The aim of this study was to characterize the enzymatic stability of 2,-ethylcarbonate-linked paclitaxel (TAX-2,-Et) in the sera of several different species including humans. TAX-2,-Et disposition in serum was kinetically analysed using models with hydrolytic and/or degradation processes. To further evaluate the capability of liver carboxylesterases (CESs) in TAX-2,-Et hydrolysis, a CES isolated from rabbit liver (Ra-CES) was utilized as a model enzyme. Rat serum provided rapid enzymatic hydrolysis of TAX-2,-Et with a half-life of 4 min. The degradation of paclitaxel (TAX) (degradation rate constant, 0.16,h,1) was accompanied by the formation of an unknown compound. The conversion to TAX was almost completely inhibited by phenylmethyl sulfonylfluoride (PMSF) and bis(p-nitrophenyl) phosphate (BNPP). In human and rabbit sera, the degradation rate constant of TAX-2,-Et was 5.1,,10,2 and 0.15,h,1, respectively, when excepting hydrolysis. The degradation products had the same molecular weight as TAX-2,-Et. The amount of TAX produced accounted for only 8,11% of the decrease in TAX-2,-Et after a 9 h exposure to rabbit or human serum. PMSF, but not BNPP, inhibited more than 90% of the TAX production in a 1.5,h incubation with human or rabbit serum. Ra-CES enzyme converted TAX-2,-Et to TAX with Vmax and Km of 74.713.8 nmol/min/mg protein and 8.82.8 M, respectively. These results indicate that TAX-2,-Et is sensitive to serum CESs, but not cholinesterases. However, serum CESs show species-dependent hydrolysis of TAX-2,-Et. Although human serum allows the slow release of TAX, TAX-2,-Et is expected to reduce the side-effects of TAX. The Ra-CES enzyme is capable of hydrolysing TAX-2,-Et, which may be beneficial for the development of a TAX-2,-Et/enzyme therapy strategy for ovarian cancer. Copyright 2008 John Wiley & Sons, Ltd. [source]


Pharmaceutical metabolites in the environment: Analytical challenges and ecological risks,

ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 12 2009
Mary D. Celiz
Abstract The occurrence of human and veterinary pharmaceuticals in the environment has been a subject of concern for the past decade because many of these emerging contaminants have been shown to persist in soil and water. Although recent studies indicate that pharmaceutical contaminants can pose long-term ecological risks, many of the investigations regarding risk assessment have only considered the ecotoxicity of the parent drug, with very little attention given to the potential contributions that metabolites may have. The scarcity of available environmental data on the human metabolites excreted into the environment or the microbial metabolites formed during environmental biodegradation of pharmaceutical residues can be attributed to the difficulty in analyzing trace amounts of previously unknown compounds in complex sample matrices. However, with the advent of highly sensitive and powerful analytical instrumentations that have become available commercially, it is likely that an increased number of pharmaceutical metabolites will be identified and included in environmental risk assessment. The present study will present a critical review of available literature on pharmaceutical metabolites, primarily focusing on their analysis and toxicological significance. It is also intended to provide an overview on the recent advances in analytical tools and strategies to facilitate metabolite identification in environmental samples. This review aims to provide insight on what future directions might be taken to help scientists in this challenging task of enhancing the available data on the fate, behavior, and ecotoxicity of pharmaceutical metabolites in the environment. [source]


Distinguishing N -oxide and hydroxyl compounds: impact of heated capillary/heated ion transfer tube in inducing atmospheric pressure ionization source decompositions

JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 6 2004
Dilrukshi M. Peiris
Abstract In the pharmaceutical industry, a higher attrition rate during the drug discovery process means a lower drug failure rate in the later stages. This translates into shorter drug development time and reduced cost for bringing a drug to market. Over the past few years, analytical strategies based on liquid chromatography/mass spectrometry (LC/MS) have gone through revolutionary changes and presently accommodate most of the needs of the pharmaceutical industry. Among these LC/MS techniques, collision induced dissociation (CID) or tandem mass spectrometry (MS/MS and MSn) techniques have been widely used to identify unknown compounds and characterize metabolites. MS/MS methods are generally ineffective for distinguishing isomeric compounds such as metabolites involving oxygenation of carbon or nitrogen atoms. Most recently, atmospheric pressure ionization (API) source decomposition methods have been shown to aid in the mass spectral distinction of isomeric oxygenated (N -oxide vs hydroxyl) products/metabolites. In previous studies, experiments were conducted using mass spectrometers equipped with a heated capillary interface between the mass analyzer and the ionization source. In the present study, we investigated the impact of the length of a heated capillary or heated ion transfer tube (a newer version of the heated capillary designed for accommodating orthogonal API source design) in inducing for-API source deoxygenation that allows the distinction of N -oxide from hydroxyl compounds. 8-Hydroxyquinoline (HO-Q), quinoline- N -oxide (Q-NO) and 8-hydroxyquinoline- N -oxide (HO-Q-NO) were used as model compounds on three different mass spectrometers (LCQ Deca, LCQ Advantage and TSQ Quantum). Irrespective of heated capillary or ion transfer tube length, N -oxides from this class of compounds underwent predominantly deoxygenation decomposition under atmospheric pressure chemical ionization conditions and the abundance of the diagnostic [M + H , O]+ ions increased with increasing vaporizer temperature. Furthermore, the results suggest that in API source decompostion methods described in this paper can be conducted using mass spectrometers with non-heated capillary or ion transfer tube API interfaces. Because N-oxides can undergo in-source decomposition and interfere with quantitation experiments, particular attention should be paid when developing API based bioanalytical methods. Copyright 2004 John Wiley & Sons, Ltd. [source]


Beer But Not Wine, Hard Liquors, or Pure Ethanol Stimulates Amylase Secretion of Rat Pancreatic Acinar Cells In Vitro

ALCOHOLISM, Issue 9 2009
Andreas Gerloff
Background:, In contrast to pure ethanol, the effect of alcoholic beverages on the exocrine pancreas is greatly unknown. Besides ethanol, alcoholic beverages contain numerous nonalcoholic constituents which might have pathophysiological effects on the pancreas. The aim of the present study was to investigate whether some commonly used alcoholic beverages and pure ethanol influence the main function of rat pancreatic acinar cells, i.e., enzyme output in vitro. Methods:, Rat pancreatic AR4-2J cells were differentiated by dexamethasone treatment for 72 hours and freshly isolated pancreatic acini were prepared from Sprague,Dawley rats using collagenase digestion. After incubation of cells in the absence or presence of 1 to 10% (v/v) beer (containing 4.7% v/v ethanol), 10% (v/v) wine (containing 10.5 to 12.5% v/v ethanol), 10% (v/v) hard liquor (such as whisky, rum, and gin), or of the corresponding ethanol concentrations (4.03 to 80.6 mM) for 60 minutes, protein secretion was measured using amylase activity assay. Results:, Incubation of AR4-2J cells with beer caused a dose-dependent stimulation of basal amylase secretion that was significant at doses of beer above 0.5% (v/v). Stimulation with 10% (v/v) beer induced 92.7 25.2% of maximal amylase release in response to the most effective cholecystokinin (CCK) concentration (100 nM). In contrast, ethanol (up to 80.6 mM) did neither stimulate nor inhibit basal amylase release. Lactate dehydrogenase measurement after treatment of AR4-2J cells with beer for 24 hours indicated that the increase of amylase release was not due to cell membrane damage. Wine and hard liquor had no effect on basal amylase secretion neither diluted to the ethanol concentration of beer nor undiluted. In freshly isolated rat pancreatic acinar cells beer dose-dependently stimulated amylase secretion in a similar manner as in AR4-2J cells. Conclusions:, Our data demonstrate that beer dose-dependently increases amylase output. Since neither ethanol nor the other alcoholic beverages tested caused stimulation of amylase release, our findings indicate that nonalcoholic constituents specific for beer are responsible for this increase. These as yet unknown compounds have to be identified and considered in further studies of ethanol-induced pathological and functional changes of the pancreas. [source]


Phenols in spikelets and leaves of field-grown oats (Avena sativa) with different inherent resistance to crown rust (Puccinia coronata f. sp. avenae)

JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 11 2009
Lena H Dimberg
Abstract BACKGROUND: Avenanthramides, health-beneficial phenols in oats, are produced in response to incompatible races of the crown rust fungus, Puccinia coronata, in seedlings of greenhouse-grown oats. This study aimed to elucidate whether avenanthramides and/or other phenolic compounds, together with the activities of phenylalanine ammonia lyase (PAL), phenoloxidase (PO) and the avenanthramide biosynthetic enzyme hydroxycinnamoyl-CoA:hydroxyanthranilate- N -hydroxycinnamoyl transferase (HHT), are associated with crown rust infection in mature field-grown oats. Nine oat (Avena sativa L.) genotypes with wide variation in crown rust resistance were exposed to naturally occurring fungal spores during the growth period. RESULTS: In the spikelets avenanthramides as well as HHT activities were more abundant in the crown rust resistant genotypes, whereas p -coumaric and caffeic acids were more abundant in the susceptible ones. In the leaves avenanthramides were not associated with resistance. Instead two unknown compounds correlated negatively with the rust score. Phenols released by alkaline hydrolysis and PAL and PO activities were not related to rust infection, either in spikelets or in the leaves. CONCLUSION: Because grains of crown rust-resistant oat genotypes seemed to have higher endogenous levels of health-promoting avenanthramides, use of resistant oats may contribute to a food raw material with health-beneficial effects. Copyright 2009 Society of Chemical Industry [source]


WS10 Development of CALUX bioassay-based systems as instruments to detect hormones and contaminants

JOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 2006
A. BROUWER
Objective Tremendous progress has been made in the ability to measure particular contaminants or veterinary drugs at very low concentrations. However, rare or previously unknown compounds, metabolites and mixtures are still presenting considerable analytical challenges, while this category in particular might be relevant in terms of food safety. In addition, the need for higher throughput screening strategies at lower costs also demands for methods in addition to chemical analysis. There is considerable development in methodology based on the interaction with bio-macromolecules or living cells or on a biological response in the exposed animal. The aim of this workshop is to provide an up-o-date and practical overview of the various analytical and biological strategies that are available to screen or detect (prior) exposure to drugs, contaminants and pollutants. [source]


WS11 Comprehensive investigation of the transcriptome

JOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 2006
T. PINEAU
Objective Tremendous progress has been made in the ability to measure particular contaminants or veterinary drugs at very low concentrations. However, rare or previously unknown compounds, metabolites and mixtures are still presenting considerable analytical challenges, while this category in particular might be relevant in terms of food safety. In addition, the need for higher throughput screening strategies at lower costs also demands for methods in addition to chemical analysis. There is considerable development in methodology based on the interaction with bio-macromolecules or living cells or on a biological response in the exposed animal. The aim of this workshop is to provide an up-o-date and practical overview of the various analytical and biological strategies that are available to screen or detect (prior) exposure to drugs, contaminants and pollutants. [source]


Comprehensive plasma-screening for known and unknown substances in doping controls

RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 8 2010
Andreas Thomas
Occasionally, doping analysis has been recognized as a competitive challenge between cheating sportsmen and the analytical capabilities of testing laboratories. Both have made immense progress during the last decades, but obviously the athletes have the questionable benefit of frequently being able to switch to new, unknown and untested compounds to enhance their performance. Thus, as analytical counteraction and for effective drug testing, a complementary approach to classical targeted methods is required in order to implement a comprehensive screening procedure for known and unknown xenobiotics. The present study provides a new analytical strategy to circumvent the targeted character of classical doping controls without losing the required sensitivity and specificity. Using 50,L of plasma only, the method potentially identifies illicit drugs in low ng/mL concentrations. Plasma provides the biological fluid with the circulating, unmodified xenobiotics; thus the identification of unknown compounds is facilitated. After a simple protein precipitation, liquid chromatographic separation and subsequent detection by means of high resolution/high accuracy orbitrap mass spectrometry, the procedure enables the determination of numerous compounds from different classes prohibited by the World Anti-Doping Agency (WADA). A new hyphenated mass spectrometry technology was employed without precursor ion selection for higher collision energy dissociation (HCD) fragmentation experiments. Thus the mass spectra contained all the desired information to identify unknown substances retrospectively. The method was validated for 32 selected model compounds for qualitative purposes considering the parameters specificity, selectivity, limit of detection (<0.1,10,ng/mL), precision (9,28%), robustness, linearity, ion suppression and recovery (80,112%). In addition to the identification of unknown compounds, the plasma samples were simultaneously screened for known prohibited targets. Copyright 2010 John Wiley & Sons, Ltd. [source]


Characterization of dihydrostreptomycin-related substances by liquid chromatography coupled to ion trap mass spectrometry

RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 12 2009
Murali Pendela
Dihydrostreptomycin sulphate (DHS) is a water-soluble, broad-spectrum aminoglycoside antibiotic. For quantitative analysis, the European Pharmacopoeia (Ph. Eur.) prescribes an ion-pairing liquid chromatography/ultraviolet (LC/UV) method using a C18 stationary phase. Several unknown compounds were detected in commercial samples. Hence, for characterization of these unknown peaks in a commercial DHS sample, the Ph. Eur. method was coupled to mass spectrometry (MS). However, since the Ph. Eur. method uses a non-volatile mobile phase, each peak eluted was collected and desalted before introduction into the mass spectrometer. The desalting procedure was applied to remove the non volatile salt, buffer and ion-pairing reagent in the collected fraction. In total, 20 impurities were studied and 14 of them were newly characterized. Five impurities which are already reported in the literature were also traced in this LC/UV method. Copyright 2009 John Wiley & Sons, Ltd. [source]


Loss of TIP1;1 aquaporin in Arabidopsis leads to cell and plant death

THE PLANT JOURNAL, Issue 6 2004
Shisong Ma
Summary Arabidopsis TIP1;1 (,TIP) is a member of the tonoplast family of aquaporins (AQP). Using RNA interference (RNAi) we reduced TIP1;1 to different extent in various lines. When most severely affected, miniature plants died, a phenotype partially complemented by the TIP1;1 homolog McMIP-F. Less severely affected lines produced small plants, early senescence, and showed lesion formation. The relative water content in TIP1;1 RNAi plants was not significantly affected. Global expression profiling suggested a disturbance in carbon metabolism in RNAi lines with upregulated transcripts for functions in carbon acquisition and respiration, vesicle transport, signaling and transcription, and radical oxygen stress. Metabolite profiles showed low glucose, fructose, inositol, and threonic, succinic, fumaric, and malic acids, but sucrose levels were similar to WT. Increased amounts were found for raffinose and several unknown compounds. TIP1;1 RNAi plants also contained high starch and apoplastic carbohydrate increased. A GFP-TIP1;1 fusion protein indicated tonoplast location in spongy mesophyll cells, and high signal intensity in palisade mesophyll associated with vesicles near plastids. Signals in vascular tissues were strongest not only in vesicle-like structures but also outlined large vacuoles. Compromised routing of carbohydrate and lack of sucrose provision for cell-autonomous functions seems to characterize this RNAi phenotype. We suggest a function for TIP1;1 in vesicle-based metabolite routing through or between pre-vacuolar compartments and the central vacuole. Phenotype and expression characteristics support a view of TIP1;1 functioning as a marker for vesicles that are targeted to the central vacuole. [source]