Showing papers by "King Faisal Specialist Hospital & Research Centre published in 2005"
TL;DR: This review article focuses on some of the recent developments in the rapidly growing field of lipase-catalyzed kinetic resolution of racemates as a versatile method for the separation of enantiomers.
242 citations
TL;DR: A complex study of antioxidant activity of genistein and oleuropein, using electron spin resonance (ESR), chemiluminescence, fluorescence and spectrophotometric techniques, confirmed good scavenging activity towards O(2).(-), HO.
Abstract: The plant-derived phenolic compounds genistein and oleuropein are known to exhibit several biological properties, many of which may result from their antioxidant and free radical scavenger activity. In this paper we report the results of a complex study of antioxidant activity of genistein and oleuropein, using electron spin resonance (ESR), chemiluminescence, fluorescence and spectrophotometric techniques. Different reaction systems were applied to study the inhibitory effect of the phenolic compounds studied: (a) the potassium superoxide[sol ]18-crown-6 dissolved in DMSO system, which generates superoxide radical (O2·−) and hydrogen peroxide (H2O2); (b) the Co(II)–EDTA–H2O2 system (the Fenton-like reaction), which generates hydroxyl radical (HO·); (c) 2,2′-azobis(2-amidino-propane)dichloride (AAPH) as the peroxyl radical (ROO·) generator, and the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical test. Results showed that genistein and oleuropein decreased the chemiluminescence sum from the O2·− generating system, an inhibitory effect that was dependent on their concentration. These compounds also reacted with ROO radicals and they showed activity about two-fold greater than the standard Trolox. The antioxidant effects were studied at different concentrations and reflected in protection against the fluorescence decay of β-phycoerythrin (β-PE), due to ROO· attack on this protein. Using the Fenton-like reaction and the spin trap agent 5,5-dimethyl-1-pyrroline-N-oxide (DMPO), the phenolic compounds examined were found to inhibit DMPO–·OH radical formation in the range 10–90% at concentrations of 0.1 mmol[sol ]L to 2 mmol[sol ]L. Furthermore, these compounds also inhibited HO·-dependent deoxyribose degradation; about 20% and 60% inhibitions were observed in the presence of 0.5 mmol[sol ]L genistein and oleuropein, respectively. It was also demonstrated that genistein had a weaker DPPH radical scavenging activity than oleuropein. Our results confirm good scavenging activity towards O2·−, HO· and ROO· and the antioxidant effect of genistein and oleuropein. Copyright © 2005 John Wiley & Sons, Ltd.
96 citations
TL;DR: In this article, a simple, reliable and reproducible HPLC and extraction method was developed for the analysis of tadalafil in pharmaceutical preparation, which is suitable for high throughput analysis of the drug.
86 citations
TL;DR: A user-friendly, one-pot procedure was developed to access racemic as well as enantiomerically enriched cyclopropanes and an enantiomers separation was achieved using gas chromatography on the chiral stationary phase Chirasil-beta-dex.
33 citations
TL;DR: A simple HPLC analysis for the ide.gification and qua. gification of vardenafil in a pharmaceutical tablet formulation was performed on a conventional C18 and Chromolith Performance RP•18e monolith in this article.
Abstract: A simple HPLC analysis for the ide.gification and qua.gification of vardenafil in a pharmaceutical tablet formulation was performed on a conventional C18 and Chromolith Performance RP‐18e monolithi...
16 citations
TL;DR: In this paper, the analysis of four trace elements (Cu, Zn, Cd, and Ni) in cows, goats, ewes, and human mature milk collected in Tokat, Turkey was carried out by flame atomic absorption spectrometry (FAAS) and microwave digestion technique method, which was used to extract the trace elements from the milk samples.
Abstract: Recently, several studies have been reported on the trace element composition of milk, especially human milk. However, there is limited study comparing different types of milk collected from different animals and humans. This study describes the analysis of four trace elements (Cu, Zn, Cd, and Ni) in cows', goats', ewes', and human mature milk collected in Tokat, Turkey. Analysis was carried out by flame atomic absorption spectrometry (FAAS) and microwave digestion technique method, which was used to extract the trace elements from the milk samples. Our results are in agreement with the values reported in the literature, with the exception of nickel concentration in ewes' milk, which has the highest value reported.
16 citations
TL;DR: In this article, a high-throughput, high performance liquid chromatographic method was developed and validated for the determination of clopidogrel in pharmaceutical dosage forms at room temperature using a reversed phase monolithic silica column Chromolith Performance 18e (100mm×4.6mm I.D.).
Abstract: A high‐throughput, high performance liquid chromatographic method was developed and validated for the determination of clopidogrel in pharmaceutical dosage forms. The analysis was performed at room temperature using a reversed phase monolithic silica column Chromolith Performance 18e (100 mm×4.6 mm I.D.). The mobile phase consisted of acetonitrile:phosphate buffer (50∶50 v/v, pH 3.0) at a flow rate of 4.0 mL/min. The photodiode array detector was set at 235 nm. The developed method showed a good linear relationship in the concentration range from 1.0 to 40.0 µg/mL with a correlation coefficient of 0.999. The limit of detection and limit of quantification were 0.97 µg/mL and 3.52 µg/mL, respectively.
15 citations
TL;DR: In this article, the authors identify underlying cathepsin C mutations in 39 subjects with Papillon-Lefevre syndrome and explore any phenotypic associations using standard molecular techniques, and dermatological and oral characteristics were assessed with a semiquantitative clinical score.
Abstract: Papillon-Lefevre syndrome is an autosomal recessive disorder characterized by palmoplantar hyperkeratosis and aggressive periodontitis. The aim of the study was to identify underlying cathepsin C mutations in 39 subjects with Papillon-Lefevre syndrome and to explore any phenotypic associations. Genotyping and mutation analyses were performed using standard molecular techniques, and dermatological and oral characteristics were assessed with a semiquantitative clinical score. Three genotypes were present at microsatellite marker D11S1780 and two underlying mutations were identified. The most common genotype (183/183) was associated with an 815G → C mutation in exon 6 resulting in an arginine to proline change at amino acid 272 (R272P). Patients with the 173/173 genotype revealed an exon 7 G300D mutation resulting in a glycine to aspartic acid change at amino acid 300. The mutation in a family with 189/189 genotype remained unknown. A significant difference in hyperkeratosis of the feet was found between the patients with mutations G300D and R272P (p <0.05), but not regarding hands or periodontal condition. Young girls displayed significantly less palmoplantar hyperkeratosis ( p <0.05) than young boys. In conclusion, considerable phenotypic heterogeneity was observed within the two cardinal mutations and in the 189/189 genotype.
13 citations
TL;DR: Three structurally related aminopyrazoloquinoline derivatives were evaluated for their antiviral activity against Herpes Simplex virus type 1 by two different bioassays, namely; crystal violet staining and tetrazolium dye measurement.
Abstract: Three structurally related aminopyrazoloquinoline derivatives were evaluated for their antiviral activity against Herpes Simplex virus type 1. These compounds were examined for their in vitro antiviral activity by two different bioassays, namely; crystal violet staining and tetrazolium dye (MTS) measurement. The antiviral role of these compounds was confirmed by enumerating the infectious particles with plaque assay. The acute toxicity values of the biologically active compounds were determined prior to their screening as antiviral agents.
13 citations
Journal Article•
TL;DR: PBLL is a distinct B-cell NHL which involves extralymphatic sites, with particular predisposition for the upper aerodigestive tract and patients should not be treated on short intensive protocols used for other B- cell NHL but should receive treatment based on ALL protocols like those for treating T-cell LL.
10 citations
TL;DR: In this article, the electrochemical reduction behavior of mefloquine HCl (MEF), the antimalarial drug, was studied in aqueous alcoholic media at a hanging mercury drop electrode.
Abstract: The electrochemical reduction behavior of mefloquine HCl (MEF), the antimalarial drug, was studied in aqueous alcoholic media at a hanging mercury drop electrode. Cyclic voltammetric studies showed one well-defined reduction peak and one ill-defined reduction wave between pH 1.5 and 12.03. The reduction was found as irreversible or quasireversible depending on pH and exhibited diffusion controlled process. The mechanism of reduction process was discussed. A systematic study of the experimental parameters that affect the differential pulse and square wave response was carried out and the optimized experimental conditions were obtained. The calibration plots were derived for the determination of MEF in pharmaceutical dosage forms and biological samples. DPV and SWV techniques for the determination of MEF in Britton–Robinson buffer at pH 11.10, which allows quantitation over the 6×10−6 to 8×10−5 M range in the supporting electrolyte, were proposed. The linear response was obtained in samples in the ranges of 6×10−6 to 6×10−5 M for both techniques. These methods are fully validated. The standard addition method was used in the biological media. No electroactive interferences from the excipients and endogenous substances were found in tablets and biological fluids.
TL;DR: A validated high performance liquid chromatographic method was developed for the determination of chromium picolinate in pharmaceutical dosage forms and showed a good linear relationship in the concentration range from 0.125 to 12.5 microg/mL with a correlation coefficient of 0.999.
Abstract: A validated high performance liquid chromatographic method was developed for the determination of chromium picolinate in pharmaceutical dosage forms. The analysis was performed at room temperature using a reversed-phase Supelcosil LC-18 (250 x 4.6 mm, 5 microm) column. The mobile phase consisted of acetonitrile:water (40:60 v/v) at a fl ow rate of 0.8 mL/min. The UV-detector was set at 264 nm. The developed method showed a good linear relationship in the concentration range from 0.125 to 12.5 microg/mL with a correlation coefficient from 0.999. The limit of detection and limit of quanti fi cation were 0.091 and 0.181 microg/mL, respectively.
TL;DR: In this paper, two new indices of IR fingerprint spectra are introduced, namely, common peak ratio and variation peak ratio, which are calculated by means of the sequent analysis method, in which each sample's IR FPS of the components extracted from Glycyrhizae root is as a standard, and the sequences are made in accordance with the values of their common peak ratios.
Abstract: This article describes a new method for analysis of IR fingerprint spectra (FPS), which characterizes traditional Chinese medicine (TCM). Two new indices of IR FPS are introduced, namely, common peak ratio and variation peak ratio. Their values are calculated by means of the sequent analysis method, in which each sample's IR FPS of the components extracted from Glycyrrhizae root is as a standard, and the sequences are made in accordance with the values of their common peak ratios. This method can distinguish the Glycyrrhizae samples correctly, which belong to different species and are produced in different regions. The dual‐index sequent method enables us to identify the Chinese herbs conveniently.
TL;DR: In this paper, the chiral resolution of 19 chiral 1,4-disubstituted piperazine derivatives with hypnotic-sedative activity has been examined on cellulose tris(4-methylbenzoate) with hexane-isopropanol mobile phases.
TL;DR: In this article, the enantiomers of cromakalim (3S,4S and 3R,4R) were resolved on polysaccharide chiral stationary phases (CSPs) under reversed phase mode.
Abstract: Cromakalim is an antihypertensive drug (potassium channel activator) that acts as potent vasodilator functioning by hyperpolarization of vascular smooth muscle membranes and opening of potassium channels. Attempts have been made to resolve the enantiomers of cromakalim (3S,4S and 3R,4R) on polysaccharide chiral stationary phases (CSPs) under reversed‐phase mode. The columns used were Chiralpak AD‐R, Chiralcel OD‐R, and Chiralcel OJ‐R. The mobile phases used were water–acetonitrile (70:30, v/v) for the Chiralpak AD‐R and the Chiralcel OD‐R columns, and water–acetonitrile (80:20, v/v) for the Chiralcel OJ‐R column. The flow rate of the mobile phases was 0.5 mL/min. The detection was carried out at 220 nm. The α‐values of the resolved enantiomers were 1.26, 1.23, and 1.13 on Chiralpak AD‐R, Chiralcel OD‐R, and Chiralcel OJ‐R columns, respectively, while the values of R s were 1.20, 0.40, and 0.30 on Chiralpak AD‐R, Chiralcel OD‐R, and Chiralcel OJ‐R columns, respectively. Concentration of cromakalim...
TL;DR: The enantioseparation of a set of new cyclopropanes derived from Meldrum's acid, dimethyl malonate, (silanoxyvinyl)-diazoacetates and 3,3,3-trifluoro-2-diazopropionate has been achieved on cellulose tris(3,5-dimethylphenylcarbamate) Chiralcel OD coated on 10μm silica-gel as chiral stationary phase in high-performance liquid chromatography (HPLC) as discussed by the authors.
TL;DR: In this paper, a review of the recent developments in this rapidly growing field demonstrating the versatility of the method in the resolution of racemates is presented, and the main emphasis is on the use of lipases in organic solvents.
Abstract: Lipase-catalyzed kinetic resolution of racemates is considered to be one of the most fascinating topics in asymmetric catalysis. This review focuses on some of the recent developments in this rapidly growing field demonstrating the versatility of the method in the resolution of racemates. The literature search is dated back to the last five years and covers some comprehensive examples. The main emphasis is on the use of lipases in organic solvents.
TL;DR: The possibilities of using theophylline (Minophyllines Suppositories—500 mg Alexandria Co.) in asthmatic children in rural and desert areas away from health care personnel are demonstrated.
Abstract: Asthma is a public health problem for developed countries. It attacks all age groups but often starts in childhood. Theophylline ethanoate of piperazine in a suppository form is one of the treatments of asthmatic children. The pharmacokinetics of theophylline were evaluated in 24 healthy male subjects after administration of theophylline ethanoate of piperazine suppositories (PR) (Minophylline 500 mg. Alexandria Co.) and single injection intravenous (IV) of theophylline ethanoate of piperazine (Minophylline ampoules 500 mg Alexandria Co.). The theophylline serum levels were determined by an ELISA method. Peak theophylline plasma concentration, Cmax, (mean +/- S.D) was 21.5 +/- 2.10 microg/mL & 14 +/- 0.90 microg/mL; AUC(0-t), values were 80.9 and 67. 4 microg x ml x hr for the reference IV preparation and suppositories, respectively. The median peak time, Tmax, was 0.5 hr for theophylline rectal administration. The above mentioned results demonstrate the possibilities of using theophylline (Minophylline Suppositories--500 mg Alexandria Co.) in asthmatic children in rural and desert areas away from health care personnel.
TL;DR: A review of recent developments in the rapidly growing field of lipase-catalyzed kinetic resolution of racemates as a versatile method for the separation of enantiomers can be found in this article.
Abstract: Lipases have been well established as valuable catalysts in organic synthesis. This review article focuses on some of the recent developments in the rapidly growing field of lipase-catalyzed kinetic resolution of racemates as a versatile method for the separation of enantiomers. The literature search dates back to the last five years and covers some comprehensive examples. The main emphasis is on the use of lipases in organic solvents.