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Articles by Mohamed A. Al-Omar
Total Records ( 5 ) for Mohamed A. Al-Omar
  Abdullah M. Al-Mohizea , Abd El-Galil E. Amr and Mohamed A. Al-Omar
  Problem statement: The role of 5-HT has been investigated in many behavioral activities. Thus, studies using raphe lesion showed that 5-HT is involved in sleep, general activity levels, habituation, aggression, pain sensitivity and morphine analgesia, avoidance behavior, self-stimulation and water consumption. Approach: The metabolic interaction between serotonin (5-hydroxytrptamine) and indole-3-aldehyde and xanthine via aldehyde oxidase (EC and xanthine oxidase (EC, respectively, were studied in liver tissue homogenate of Dunkin-Hartley guinea pigs by following the decrease in substrate concentration using spectrophotometer. Homogenates of liver were incubated with indole-3-aldehyde in the presence and absence of serotonin or (chlorpromazine and allopurinol a potent and selective inhibitors for aldehyde oxidase and xanthine oxidase, respectively). Oxidation of indole-3-aldehyde to indole-3-acetic acid was reduced up to 63.2% in the presence of serotonin (100 μM), while oxidation of xanthine to uric acid was reduced up to 51.6% under the same conditions. Results: In comparison, incubation of the substrates with their specific inhibitors (100 μM of chlorpromazine and 100 μM allopurinol) give almost complete inhibition. These results demonstrate that in the guinea pig liver a metabolic interaction between serotonin and indole-3-aldehyde or xanthine via molybdenum hydroxylases system may take place in liver, which is the main tissue for xenobiotics detoxification. Conclusion: The overall conclusion from this research is that serotonin could be a protector for neurons and other tissue from the insult of oxidation of aldehydes and xanthines by molybdenum hydroxylases.
  Suzan Khayyat , Abd El-Galil E. Amr , Osama I. Abd El- Salam , Mohamed A. Al-Omar and Mohamed M. Abdalla
  A series of bis-schiff base candidates 5a-l, 6a-c and 7a-c were synthesized by using N2, N2`-(pyridine-3,5-dicarbonyl)-di-L-lucylhydrazide (4) as starting material which was synthesized from 3,5-pyridinedicarboxylic acid (1) and screening for their analgesic and anti-inflammatory. Bis-ester 3 was prepared from 3,5-pyridinedi-carboxylic acid 1 and L-lucine methyl ester, which was hydrazonolysis with hydrazine hydrate afforded compounds 4. Treatment of acid hydrazide 4 with aromatic aldehydes afforded the corresponding bis-dipeptide Schiff bases 5a-l, respectively. Compounds 6a-c and 7a-c were synthesized by reacting of hydrazide 4 with cycloalkanone and acetyl pyridine derivatives. Some of the newly synthesized compounds exhibited better analgesic and anti-inflammatory activities than the reference controls. The structures of newly synthesized compounds were confirmed by IR, NMR, MS spectral data and elemental analysis. The detailed synthesis, spectroscopic data, pharmacological activities of the synthesized compounds was reported.
  Abd El-Galil E. Amr , Mohamed A. Al-Omar and Mohamed M. Abdalla
  Ten pyridine and pyrimidine and thiazolopyrimidine derivatives (1-10) were synthesized and screened as analgesic, anticonvulsant and antiparkinsonian agent beforeTen pyridine and pyrimidine and thiazolopyrimidine derivatives (1-10) were synthesized and screened as analgesic, anticonvulsant and antiparkinsonian agent before. Herein, all the target compounds showed anti-inflammatory activity. The active compounds showed selective inhibitory activity towards COX-2 enzyme as revealed by the in vitro enzymatic assay. All the tested compounds proved to have superior gastrointestinal (GI) safety profiles as compared to indomethacin, when tested for their ulcerogenic effects.

  Mohamed A. Al-Omar , Christine Beedham , F. Belal , John A. Smith and Ali A. El-Emam
  A scopoletin-based fluorimetric assay for the measurement of hydrogen peroxide formed by aldehyde oxidase was developed using sodium azide as an inhibitor of scavenging enzymes. The assay involves the coupled oxidation of scopoletin by hydrogen peroxide, catalysed by horseradish peroxidase and subsequent measurement of the change in scopoletin fluorescence. Hydrogen peroxide concentrations were measured against scopoletin fluorescence using two different scopoletin standards ranging from 0.1-2 and 4-40 μM. The overall linear correlation coefficient (r) for hydrogen peroxide concentrations ranging from 0.1-40 μM against fluorescence response is 0.998 (n = 3). The initial rates of hydrogen peroxide production by aldehyde oxidase were similar for both nitrogen heterocycles and aldehyde substrates. Initial rates of hydrogen peroxide formation during the oxidation of 100 μM substrates, indole-3-aldehyde or 2-pyrimidinone by aldehyde oxidase in the presence of 1 mM sodium azide were found to be 86-89% of substrate oxidation. All specific aldehyde oxidase inhibitors such as chlorpromazine (p<0.001), menadione (p<0.05) and β-estradiol (p<0.001), caused highly significant inhibition of hydrogen peroxide production during the oxidation of phthalazine, indole-3-aldehyde, 2-pyrimidinone and phenanthridine by guinea pig liver aldehyde oxidase. The kinetic constants, Km and Vmax, for hydrogen peroxide production during phthalazine and indole-3-aldehyde oxidation by guinea pig liver aldehyde oxidase have been determined for the first time using this method.
  Mohamed A. Al-Omar
  2-hydroxy-1,4-naphthoquinone (HNQ; Lawsone, CAS 83-72-7) is the main dye ingredient found in the natural plant of Henna (Lawsonia inermis). The percentages of superoxide anion (O2.) and hydrogen peroxide (H2O2,) formation during the oxidation of 100 μM phenanthridine by guinea pig aldehyde oxidase have been measured and found to be 6-10% and 85-90%, respectively. The effect of HNQ on the initial rates of phenanthridine oxidation, hydrogen peroxide formation and superoxide anion with aldehyde oxidase was investigated and compared with those of xanthine oxidase. It was found that HNQ is a specific inhibitor of aldehyde oxidase in vitro. In this study, HNQ inhibits the production of superoxide anion and substrate oxidation more potently than hydrogen peroxide. Thus, the site of interaction is thought to be flavin semiquinone, FADH.. The IC50 value of HNQ with phenanthridine oxidation by aldehyde oxidase is 9.3±1.1 μM, which in excess of 15 fold of maximal plasma concentrations (Cmax) of HNQ, indicating a high degree of safety margin. The interaction of HNQ with aldehyde oxidase has been also investigated using different electron acceptors including, oxygen, potassium ferricyanide and cytochrome c and found to be equipotent.
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