King Faisal Specialist Hospital & Research Centre

About: King Faisal Specialist Hospital & Research Centre is a healthcare organization based out in Riyadh, Saudi Arabia. It is known for research contribution in the topics: Detection limit & High-performance liquid chromatography. The organization has 58 authors who have published 157 publications receiving 3527 citations.

Enantioseparation of some clinically used drugs by HPLC using cellulose Tris (3,5-dichlorophenylcarbamate) chiral stationary phase.

Abstract: The chiral resolution of some clinically used drugs namely metoprolol, teratolol, tolamolol, nebivolol (β-adrenergic blockers), econazole, miconazole (anti-fungal agents), cromakalim (anti-hypertensive agent) and etodolac (anti-inflammatory agent) was achieved on cellulose tris (3,5-dichlorophenylcarbamate) chiral stationary phase. The mobile phase used was 2-propanol at 0.5 mL/min with detection at 220 nm. The separation factors (α) of these drugs ranged from 1.24 to 3.90 while the resolution factors were from 1.05 to 5.0. The chiral recognition mechanisms between the racemates and the chiral selector are discussed. Copyright ­© 2003 John Wiley & Sons, Ltd.

Scavenging of reactive oxygen species by the plant phenols genistein and oleuropein.

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.

Macrocyclic antibiotics as effective chiral selectors for enantiomeric resolution by liquid chromatography and capillary electrophoresis

Abstract: The separation of enantiomers by liquid chromatography and capillary electrophoresis is important in pharmaceutical, environmental, and agricultural analysis. Of the different types of chiral selector used for enantiomer resolution the macrocyclic antibiotics are considered particularly effective. Only eight antibiotics, vancomycin, teicoplanin, thiostrepton, rifamycin B, kanamycin, streptomycin, fradiomycin, and ristocetin A have yet been used as chiral selectors for separation of the enantiomers of a variely of compounds by liquid chromatography and capillary electrophoresis. This review describes the chemistry of these antibiotics, the effect of chromatographic conditions on enantioselectivity, the mechanism of resolution, the applications and limitations of the compounds, and detection in liquid chromatography and capillary electrophoresis with these antibiotics as the chiral selectors.