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Articles by M.A. Al-Omar
Total Records ( 3 ) for M.A. Al-Omar
  M.A. Al-Omar , S.T. Al-Rashood , H.I. El-Subbagh and S.G. Abdel Hamide
  Aldehyde oxidase and xanthine oxidase are molybdenum-containing enzymes distributed throughout animal kingdom. Aldehyde oxidase has a wide range of substrates including aldehydes and N-heterocycles while xanthine oxidase involves in oxidation of purine analogues to corresponding uric acid. In addition to cytochrome P450 isoenzymes, molybdenum hydroxylases are major defense mechanism for the removal of drugs/xenobiotics from the body. Fifty quinazoline derivatives have been synthesized and characterized by NMR infrared, mass spectrum and elementary analyses. These substituted quinazolines have been examined for their interaction with mol ybdenum hydroxylases and found to be weak inhibitor. They inhibit both enzymes in a competitive pattern with inhibitor constants (Ki) values ranging from 90-1200 μM. The relationship between Ki and relative lipophilicity of quinazolines, as inhibitors of molybdenum hydroxylase enzymes, has been compared. The specific-site of interaction and inhibitory potency of quinazolines on molybdenum hydroxylase have been discussed in this study.
  M.A. Al-Fayez , A.M. Aleisa and M.A. Al-Omar
  In the present study 27 different quinazoline derivatives have been synthesized and investigated as substrate or inhibitor for molybdenum hydroxylases. These compounds have been identified using NMR, mass spectrum, infrared and elementary analysis. In vitro, the oxidation of xanthine and phthalazine by xanthine oxidase and aldehyde oxidase from guinea pig liver, respectively, had been inhibited notably by 6-iodo-quinazolines. Although xanthine and phthalazine are excellent and specific substrates, allopurinol (100 μM) and menadione (100 μM) as specific inhibitors of xanthine oxidase and aldehyde oxidase, respectively, have been used to characterize the specificity of reaction. The inhibitory specificity as well as the active site requirements have been discussed and compared with their relative lipophilicities. 6-Iodo-substituted quinazolines inhibit both aldehyde oxidase and xanthine oxidase in a competitive pattern with Ki or IC50 ranging from 48 to 700 μM. This study indicates strongly that un-fused pyrimidine ring is required for inhibitory activity of quinazoline derivatives (see Q17 and Q21).
  M.A. Al-Omar
  In this report, collected data indicate the positive effect of olanzapine with high safety of margin. Combined therapy of olanzapine in the treatment of different subtype of bipolar disorder has a considerable benefit. It is appear that there is an agreement about olanzapine as a drug of choice in treatment of bipolar disorder. Consequently, further clinical studies are required with large number of population.
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