Biomedical subjects

S M Abdallah

Publications and source records attributed to S M Abdallah.

4 recordsLinked to original sources

PubMed2005

Synthesis and structure investigation of the antibiotic amoxicillin complexes of d-block elements.

The study of some transition metals (M) and amoxicillin trihydrate (ACT) ligand complexes (M-ACT) that formed in solution involved the spectrophotometric determination of stoichiometric ratios and their stability constants and these ratios were found to be M:ACT = 1:1, 1:2 and 2:1 in some instances. The calculated stability constants of these chelates, under selected optimum conditions, using molar ratio method have values ranging from K(f) = 10(7) to 10(14). These data were confirmed by calculations of their free energy of formation deltaG, which corresponded to their high stabilities. The separated solid complexes were studied using elemental analyses, IR, reflectance spectra, magnetic measurements, mass spectra and thermal analyses (TGA and DTA). The proposed general formulae of these complexes were found to be ML(H2O)w(H2O)x(OH)y(Cl)2, where M = Fe(II), Co(III), w = 0, x = 2, y = 1, z = 0; M = Co(II), w = 0, x = 1, y = 0, z = 1; M = Fe(III), w = 0, x = 1, y = 2, z = 0; M = Ni(II), Cu(II) and Zn(II), w = 2, x = 0, y = 1, z = 0, where w = water of crystallization, x = coordinated water, y = coordinated OH(-) and z = Cl- in the outer sphere of the complex. The IR spectra show a shift of nu(NH) (2968 cm(-1)) to 2984-2999 cm(-1) of imino group of the ligand ACT and the absence of nu(CO) (beta-lactame) band at 1774 cm(-1) and the appearance of the band at 1605-1523 cm(-1) in all complexes suggest that 6,7-enolization takes place before coordination of the ligand to the metal ions. The bands of M-N (at 625-520 cm(-1)) and of M-O (at 889-7550 cm(-1)) proved the bond of N (of amino and imino groups) and O of C-O group of the ligand to the metal ions. The reflectance spectra and room temperature magnetic measurements refer to octahedral complexes of Fe(II) and Fe(III); square planner form of Co(II), reduced Co(III), Ni(II) and Cu(II)-ACT complexes but tetrahedral form of Zn-ACT complex. The thermal degradation of these complexes is confirmed by their mass spectral fragmentation. These data confirmed the proposed structural and general formulae of these complexes.

Amoxicillin↗

PubMed2004

Synthesis, characterization and electronic spectra of cefadroxil complexes of d-block elements.

Cefadroxil (CD) is an essential pharmaceutical drug used in curing many diseases. Due to its popular use in many pharmaceutical forms, attention is paid in this research to the synthesis and stereochemistry of new iron, cobalt, nickel, copper, and zinc complexes of this drug both in solution and the solid states. The spectra of these complexes in solution and the study of their stoichiometry refer to the formation of 1:1 and 1:2 ratios of metal (M) to ligand (L). The calculated stability constants (Kf) of these complexes (1.5x10(7) to 5x10(13)) and the change in free energy of formation (deltaGf=2.5-12.5 kcal mol(-1) degree(-1)) are indicative of their high stability. The stereo chemical structure of the solid complexes was studied on the basis of their analytical, spectroscopic, magnetic, and thermal data. Infrared spectra proved the presence of M-N and M-O bonds. Magnetic susceptibility and solid reflectance spectral measurements were used to infer the structure. The prepared complexes were found to have the general formulae [ML(OH)x(H2O)y](H2O)z-M: Fe(II), x=0, y=2, z=1; M: Fe(III) and Co(III), x=1, y=2, z=1; M: Co(II) and Zn(II), x=0, y=1, z=0; M: Ni(II) and Cu(II), x=1, y=0, z=1; L: CD. Octahedral and tetrahedral structures were proposed for these complexes depending upon the magnetic and reflectance data and were confirmed by detailed mass and thermal analyses comparative studies.

Anti-Bacterial Agents↗

PubMed1993

The effect of increasing dietary zinc on the activity of superoxide dismutase and zinc concentration in erythrocytes of healthy female subjects.

Zinc has many diverse functions and is essential for growth and development. Although a number of dietary constituents inhibit its absorption, a reliable index of zinc intake and/or bioavailability remains to be identified. The aim of this study was to test the hypothesis that recent changes in zinc intake and/or bioavailability are reflected in a subfraction of erythrocytes. Six healthy female volunteers were asked to supplement their diet with 50 mg of elemental zinc per day for 12 days. Venous blood samples were obtained before and during supplementation at 4-day intervals. A subfraction of erythrocytes was isolated from each sample and zinc concentration was measured in this subfraction, in the unfractionated erythrocytes and in the plasma. These showed no significant temporal change. Erythrocyte superoxide dismutase (E-SOD), a marker of copper status, showed a significant 20% decrease (P < 0.02) in its activity in both the subfraction and the unfractionated erythrocytes following supplementation. Hence, a detrimental effect on copper metabolism (as measured by the marker enzyme E-SOD) can be detected within 12 days of supplementation with a moderate amount of zinc.

Administration, Oral↗

PubMed1980

Pulmonary function in men with intermittent long-term exposure to hyperbaric oxygen.

The effect of intermittent exposure to hyperbaric oxygen over a long period of time was evaluated in 65 subjects. Pulmonary ventilation and diffusion capacities were measured in 65 divers as well as in 67 control subjects. No significant difference was found (P < 0.05) in any of the measured respiratory parameters between the divers and the controls in spite of the diver's long-term occupational exposure to hyperbaric oxygen.

Adult↗