Home About us Contact
|
Home About us Contact | ||
|
|
||
High-performance Liquid Chromatography/mass Spectrometry (high-performance + liquid_mass_spectrometry)
Selected AbstractsFlavonol glycosides and antioxidant capacity of various blackberry and blueberry genotypes determined by high-performance liquid chromatography/mass spectrometryJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 13 2005Mi Jin Cho Abstract Flavonol glycoside composition and content in blueberry and blackberry extracts were determined using a high-performance liquid chromatographic (HPLC) separation method coupled with photodiode array (PDA) and mass spectrometric (MS) detection. The hydrophilic antioxidant capacities of crude and fractionated flavonol extracts were also determined by the oxygen radical-absorbing capacity (ORACFL) and photochemiluminescence (PCL) assays. Eight flavonols of quercetin and quercetin,sugar conjugates were identified in Kiowa blackberry, namely rutinoside, galactoside, methoxyhexoside, glucoside, pentoside, [6,-(3-hydroxy-3-methylglutaroyl)]-,-galactoside, glucosylpentoside and oxalylpentoside. Thirteen flavonols were detected in Ozarkblue blueberry. Of these, myricetin 3-hexoside and 12 quercetin,sugar conjugates, namely rutinoside, galactoside, methoxyhexoside, glucoside, pentoside, glucosylpentoside, caffeoylglucoside, oxalylpentoside, rhamnoside, dimethoxyrhamnoside, acetylgalactoside and acetylglucoside, were identified. In Bluecrop blueberry, two additional quercetin,sugar conjugates were identified, namely glucuronide and caffeoylgalactoside. Quercetin glycosides accounted for 75% of total flavonols in the blueberry genotypes. Total flavonol contents ranged from 99 to 150 mg kg,1 for blackberries and from 192 to 320 mg kg,1 for blueberries. Quenching of peroxyl and superoxide anion radicals by the flavonol fractions ranged from 1.5 to 2.3 mmol Trolox equivalents (TE) kg,1 and from 0.5 to 0.7 mmol TE kg,1 respectively for blackberries and from 2.9 to 5.2 mmol TE kg,1 and from 0.8 to 1.4 mmol TE kg,1 respectively for blueberries. The HPLC method allowed for complete separation and identification of flavonols commonly found in blackberries, and blueberries. Our results showed that blueberry and blackberry genotypes varied significantly in flavonol content and antioxidant capacity. Even though total flavonol content did not correlate well with antioxidant capacity, their ability to scavenge peroxyl and superoxide anion radicals was apparent. Copyright © 2005 Society of Chemical Industry [source] Characterization of urinary metabolites of testosterone, methyltestosterone, mibolerone and boldenone in greyhound dogsJOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 3 2000T. M. Williams Androgenic steroids are used in female greyhound dogs to prevent the onset of estrus; moreover, these steroids also have potent anabolic activity. As anabolic steroids increase muscle mass and aggression in animals, the excessive use of these agents in racing greyhounds gives an unfair performance advantage to treated dogs. The biotransformation of most anabolic steroids has not been determined in greyhound dogs. The objective of the present study was to identify the urinary metabolites of testosterone, methyltestosterone, mibolerone, and boldenone in greyhound dogs. These steroids were administered orally (1 mg/kg) to either male or female greyhound dogs and urine samples were collected pre-administration and at 2, 4, 8, 12, 24, 72, and 96 h post-administration. Urine extracts were analyzed by high-performance liquid chromatography/mass spectrometry (HPLC/MS) to identify major metabolites and to determine their urinary excretion profiles. Major urinary metabolites, primarily glucuronide, conjugated and free, were detected for the selected steroids. Sulfate conjugation did not appear to be a major pathway for steroid metabolism and excretion in the greyhound dog. Phase I biotransformation was also evaluated using greyhound dog liver microsomes from untreated dogs. The identification of several in vivo steroid metabolites generated in this study will be useful in detecting these steroids in urine samples submitted for drug screening. [source] High-performance liquid chromatography/mass spectrometric and proton nuclear magnetic resonance spectroscopic studies of the transacylation and hydrolysis of the acyl glucuronides of a series of phenylacetic acids in buffer and human plasmaRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 20 2010Elin S. Karlsson The use of high-performance liquid chromatography/mass spectrometry (HPLC/MS) and proton nuclear magnetic resonance (1H NMR) spectroscopy for the kinetic analysis of acyl glucuronide (AG) isomerisation and hydrolysis of the 1-,- O -acyl glucuronides (1-,- O -AG) of phenylacetic acid, (R)- and (S)-,-methylphenylacetic acid and ,,,-dimethylphenylacetic acid is described and compared. Each AG was incubated in both aqueous buffer, at pH 7.4, and control human plasma at 37°C. Aliquots of these incubations, taken throughout the reaction time-course, were analysed by HPLC/MS and 1H NMR spectroscopy. In buffer, transacylation reactions predominated, with relatively little hydrolysis to the free aglycone observed. In human plasma incubations the calculated rates of reaction were much faster than for buffer and, in contrast to the observations in buffer, hydrolysis to the free aglycone was a significant contributor to the overall reaction. A diagnostic analytical methodology based on differential mass spectrometric fragmentation of 1-, -O- AGs compared to the 2-, 3- and 4-positional isomers, which enables selective determination of the former, was confirmed and applied. These findings show that HPLC/MS offers a viable alternative to the more commonly used NMR spectroscopic approach for the determination of the transacylation and hydrolysis reactions of these AGs, with the major advantage of having the capability to do so in a complex biological matrix such as plasma. Copyright © 2010 John Wiley & Sons, Ltd. [source] Characterisation of oxazepam degradation products by high-performance liquid chromatography/electrospray ionisation mass spectrometry and electrospray ionisation quadrupole time-of-flight tandem mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 5 2010Thomas J. P. Smyth Oxazepam has been subjected to controlled degradation at 100°C for 3,h in 0.5,M HCl and 0.5,M NaOH. Following neutralisation of the degradation mixture and removal of salts by solid-phase extraction (SPE), isocratic high-performance liquid chromatography/mass spectrometry (HPLC/MS) using water/methanol (25:75,v/v) as the mobile phase was carried out using a flow diverter to collect fractions prior to their characterisation by electrospray ionisation multi-stage mass spectrometry (ESI-MSn) and proposal of the corresponding fragmentation patterns. The elemental compositions of the degradation products and their MS fragments were evaluated using electrospray ionisation quadrupole time-of-flight tandem mass spectrometry (ESI-QTOF-MS/MS) which was then used to support the proposed fragmentation patterns. Copyright © 2010 John Wiley & Sons, Ltd. [source] A mass spectrometry based functional assay for the quantitative assessment of ABC transporter activityRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 21 2009Mária Katona ATP-Binding Cassette (ABC) transporters are highly expressed in pharmacological barriers limiting the access of drugs to their targets. Since characterization of a compound as a transporter substrate or inhibitor bears significant consequences in drug development, there is a great need for reliable tools that enable the rapid analysis of the transport susceptibility of drugs. Here we describe a simple but very efficient high-performance liquid chromatography/mass spectrometry (HPLC/MS) assay for measuring the ABC transporter-dependent vesicular transport of compounds. In addition, we provide evidence that the requirement for sample preparation can be minimized using desorption electrospray ionization (DESI)-MS, paving the way for a direct, high-throughput investigation of drug-transporter interactions. Copyright © 2009 John Wiley & Sons, Ltd. [source] | ||||||||||