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Reverse-phase HPLC Method (reverse-phase + hplc_method)
Selected AbstractsOptimization and validation of a chromatographic method for the simultaneous quantification of six bioactive compounds in Rhizoma et Radix Polygoni CuspidatiJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 1 2008Guangsheng Qian ABSTRACT A reverse-phase HPLC method was developed for simultaneous quantification of six bioactive compounds in Rhizoma et Radix Polygoni Cuspidati. These compounds , polydatin (1), resveratrol (2), rhein (3), emodin (4), chrysophanol (5) and physcion (6) , were analysed from 24 authentic samples of the herb using UV HPLC. Based on the UV absorption characteristics of the six compounds, absorption wavelengths of 306 nm were chosen to quantify compounds 1 and 2, and 290 nm for compounds 3,6. A reliable and reproducible quantitative HPLC method for analysing authentic samples of Rhizoma et Radix Polygoni Cuspidati from different cultivation regions was developed. The results showed that the concentration of compound 1 in samples from Sichuan was almost 2-fold higher than that of samples acquired in Guangxi. Furthermore, compounds 3 and 5 were not found in all the samples tested. Thus, instead of using polydatin (1) and emodin (4) as markers for quality assessment, as in conventional practice, these findings show that compounds 2 and 6 are more suited to act as marker compounds for a more specific assessment of the quality of this herb. [source] Quantitative determination of anti-fungal and insecticide amides in adult plants, plantlets and callus from Piper tuberculatum by reverse-phase high-performance liquid chromatographyPHYTOCHEMICAL ANALYSIS, Issue 5 2003Hosana M. Debonsi Navickiene Abstract A rapid, sensitive and reliable reverse-phase HPLC method was used for the quantitative determination of the anti-fungal and insecticide amides, dihydropiplartine (1), piplartine (2), ,,,, -dihydropiperine (3) and pellitorine (4) in plants in natura, in plantlets in vitro and ex vitro, and in callus of Piper tuberculatum. Well-resolved peaks were obtained with good detection response and linearity in the range of 15.0,3000 µg/mL. The plants in natura contained compounds 1,4, the plantlets ex vitro and in vitro accumulated compounds 1,2 and 1,4, respectively, while only amide 4 was found in callus. Copyright © 2003 John Wiley & Sons, Ltd. [source] Quantitative determination of cytotoxicFriedo-nor -oleanane derivatives from five morphological types of Maytenus ilicifolia (celastraceae) by reverse-phase high-performance liquid chromatographyPHYTOCHEMICAL ANALYSIS, Issue 2 2002Waldemar Buffa Filho Abstract Five different morphological types of Maytenus ilicifolia of the same age and harvested under the same conditions showed distinct accumulations of some friedo-nor -oleananes. A rapid, sensitive and reliable reverse-phase HPLC method (employing an external standard) was used for the determination of the cytotoxic triterpenoids, 20,-hydroxymaytenin, 22,-hydroxymaytenin, maytenin, celastrol and pristimerin in each of the five types. Well resolved peaks with good detection response and linearity in the range1.0,100,µg/mL were obtained. Copyright © 2002 John Wiley & Sons, Ltd. [source] An HPLC assay for the lipophilic camptothecin analog AR-67 carboxylate and lactone in human whole bloodBIOMEDICAL CHROMATOGRAPHY, Issue 10 2010Eleftheria Tsakalozou Abstract AR-67 (7-t-butyldimethylsilyl-10-hydroxycamptothecin, DB-67) is a camptothecin analog currently in early stage clinical trials. The lactone moiety of camptothecins hydrolyzes readily in blood to yield the pharmacologically inactive carboxylate form. However the lactone form of third-generation lipophilic congeners, such as AR-67, is more stable, possibly due to partitioning into red cell membranes. This prompted us to develop a reverse-phase HPLC method with fluorescence detection (excitation 380,nm/emission 560,nm), which could quantitate the concentration of AR-67 lactone and carboxylate in whole blood. Samples were prepared by red cell lysis, protein precipitation with methanol and centrifugation to remove denatured materials. Recovery was estimated to be >85%. Analytes were eluted isocratically with 0.15,m ammonium acetate buffer containing 10,mm TBAP (pH 6.5) and acetonitrile (65:35, v/v) on a Nova-Pak C18 column (4,µm; 3.9 × 150,mm). The assay was linear in the ranges 0.5,300 and 2.5,300,ng/mL for carboxylate and lactone, respectively. Accuracy and precision were acceptable. AR-67 forms were stable in whole blood and in methanolic supernatants. This assay has been successfully applied to measure AR-67 concentrations in whole blood of patients enrolled in a phase I study. Copyright © 2010 John Wiley & Sons, Ltd. [source] High-performance liquid chromatographic method for identification and quantification of two isomeric coumarinolignoids,cleomiscosin A and cleomiscosin B,in extracts of Cleome viscosaBIOMEDICAL CHROMATOGRAPHY, Issue 11 2007Sunil K. Chattopadhyay Abstract A simple, accurate and reproducible reverse-phase HPLC method has been developed for identification and quantification of two isomeric coumarinolignoids, cleomiscosin A and B in different extracts of the seeds of Cleome viscosa using photodiode array detection at 326 nm. Cleomiscosin A and B were separated on a Waters symmetry C18 column (250 × 4.6 mm with 5.0 µm particle size) with an isocratic elution system composed of acetonitrile,methanol (1:2, v/v) and acetic acid,water (0.5:99.5, v/v) in the ratio of 40:60 (v/v). The calibration curves were linear (r2 > 0.997) in the concentration ranges of 20,100 µg/mL for both compounds. The limits of detection and quantification were 15 and 20 µg/mL for both cleomiscosin A and B. The intra- and inter-day precisions were 3.68 and 2.22% for cleomiscosin A and 4.22 and 5.06% for cleomiscosin B. The recoveries measured at two different concentration levels varied from 98.03 to 110.06%. The method was used to identify and quantify cleomiscosins A and B in different extracts of Cleome viscosa seeds. Copyright © 2007 John Wiley & Sons, Ltd. [source] Synthesis and analysis of aminochromes by HPLC-photodiode array.BIOMEDICAL CHROMATOGRAPHY, Issue 1 2003Adrenochrome evaluation in rat blood Abstract The catecholamine oxidation process induces cardiotoxicity and neurotoxicity. Catecholamines can oxidize to aminochromes through autoxidation or by enzymatic or non-enzymatic catalysis. Although some toxic effects seem to be related to the formation of aminochromes there is still scarce information concerning the identification and evaluation of these compounds in in vivo models. In this study five catecholamines were oxidized to their respective aminochromes: adrenaline/adrenochrome; noradrenaline/noradrenochrome; dopa/dopachrome; dopamine/dopaminochrome; and isoproterenol/isoprenochrome. The evaluation of the catecholamines oxidation profile was performed by HPLC with photodiode array detection and using either enzymatic (tyrosinase) or non-enzymatic [Ag2O, CuSO4, NaIO4 and K3Fe(CN)6] catalytic systems. The NaIO4 was found to be the most efficient oxidant of catecholamines. An isocratic reverse-phase HPLC method was developed to analyse each pair of catecholamine,aminochrome. The analytical system was then applied to the detection of adrenochrome in rat blood at 490,nm. Thus, adrenochrome was administered i.p. to rats and its concentration in whole blood was monitored after 5, 15 and 25,min. Blood treatment for adrenochrome evaluation consists of an acidification for protein precipitation followed by a rapid neutralization. The results showed a rapid decrease of adrenochrome concentration in blood after its administration. The adrenochrome present in blood was characterized by UV and tandem mass spectrometry. Copyright © 2002 John Wiley & Sons, Ltd. [source] Complete bioavailability and lack of food-effect on pharmacokinetics of gliclazide 30 mg modified release in healthy volunteersBIOPHARMACEUTICS AND DRUG DISPOSITION, Issue 4 2002P. Delrat Abstract A new modified release (MR) formulation containing 30 mg of gliclazide was developed to obtain a better predictable release of the active principle and to allow once-daily dosing regimen. An absolute bioavailability study was carried out to characterise the performance of the new formulation and the food-effect was also investigated in a separate study. Both studies were single dose, randomised, open label, two way cross over studies with a wash out period between doses. For the bioavailability study, each volunteer received 30 mg of gliclazide given either as a 1 h intravenous infusion or as a 30 mg MR tablet. For the food-effect study, the treatment was given either fasted or 10 min after the start of a standardised Melander breakfast. Blood samples were collected up to 72 h after administrations and plasma samples assayed for gliclazide concentrations using a reverse-phase HPLC method with UV detection. Mean absolute bioavailability of gliclazide was 97% and ranged between 79 and 110% showing complete absorption. A similar moderate to low variability was observed after IV and oral administration showing the MR formulation did not add to the overall variability which is solely due to the disposition parameters, in particular metabolism of gliclazide. No significant difference was observed in tmax, t1/2z, Cmax and AUC of gliclazide after administration of the 30 mg MR tablet under fasted and fed conditions. In conclusion, after single oral administration of a 30 mg MR tablet, gliclazide was completely absorbed both under fasted and fed conditions. A consistent and optimal release of gliclazide from this formulation leads to a low to moderate overall variability of its pharmacokinetic parameters. Diamicron 30 mg MR can be given without regards to meals i.e. before, during or after breakfast. Copyright © 2002 John Wiley & Sons, Ltd. [source] | |||||||||||||