title: Effect of Cd, Zn and Hg complexes of barbituric acid and thiouracil on rat brain monoamine oxidase-B (in vitro).
abstract: Metal pyrimidine complexes (MPCs) including cadmium-barbiturate (Cd-BA), zinc-barbiturate (Zn-BA), cadmium-thiouracil (Cd-TU) and mercury-thiouracil (Hg-TU) were prepared and their analysis was carried out. These MPCs were evaluated as monoamine oxidase-B (MAO-B) inhibitors. Rat brain MAO-B was inhibited (in vitro) by Cd-BA, Zn-BA, Cd-TU and Hg-TU complexes. The inhibition of MAO-B by these complexes was time and concentration dependent. The values of IC50 of Zn-BA, Cd-BA, Hg-TU and Cd-TU were 10.2, 15.8, 16.2 and 20.4 nM, respectively. The effect of different substrate concentrations in the absence and in the presence of MPCs was determined. Lineweaver-Burk plots were plotted and the values of apparent Michaelis constant (Km), maximum velocity (Vmax), the dissociation constant of enzyme inhibitor complex (Ki) and the percent of inhibition (i%) were calculated. The data showed that the inhibition of MAO-B by all studied MPCs was the non-competitive type. The sequence of inhibition zone was: Zn-BA>Cd-BA and Hg-TU>Cd-TU affected by the chemistry of both the metal and the ligand. Otherwise, the results of the present study showed that the inhibition of MAO-B by all MPCs was fully reversible. The data showed that the presence of Cd-BA, Zn-BA, Cd-TU and Hg-TU complexes changed the optimum temperature and pH of MAO-B.
authors.affiliation: Biochemistry Department, Faculty of Science, Alexandria University, Alexandria, Egypt.
authors.forename: Nadia Z
authors.initials: NZ
authors.lastname: Shaban
authors.affiliation: Chemistry Department, Faculty of Science, Alexandria University, Alexandria, Egypt.
authors.forename: Mamdouh S
authors.initials: MS
authors.lastname: Masoud
authors.affiliation: Biochemistry Department, Faculty of Science, Alexandria University, Alexandria, Egypt.
authors.forename: Doaa
authors.initials: D
authors.lastname: Awad
authors.affiliation: Biochemistry Department, Faculty of Science, Alexandria University, Alexandria, Egypt.
authors.forename: Mai A
authors.initials: MA
authors.lastname: Mawlawi
authors.affiliation: Biochemistry Department, Faculty of Science, Alexandria University, Alexandria, Egypt.
authors.forename: Omayma M
authors.initials: OM
authors.lastname: Sadek
mesh_terms: D000818:Animals; D001463:Barbiturates / Q000494:pharmacology*; D001921:Brain / Q000187:drug effects* / Q000201:enzymology* / Q000378:metabolism; D002104:Cadmium / Q000494:pharmacology; D004347:Drug Interactions; D006863:Hydrogen-Ion Concentration; D008297:Male; D008628:Mercury / Q000494:pharmacology; D019216:Metals, Heavy / Q000494:pharmacology*; D008995:Monoamine Oxidase / Q000378:metabolism*; D008996:Monoamine Oxidase Inhibitors / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013696:Temperature; D013889:Thiouracil / Q000494:pharmacology*; D015032:Zinc / Q000494:pharmacology
chemical_list: D001463:Barbiturates; D019216:Metals, Heavy; D008996:Monoamine Oxidase Inhibitors; D002104:Cadmium; D013889:Thiouracil; D008995:Monoamine Oxidase; D008628:Mercury; D015032:Zinc; C032232:barbituric acid
keywords: Barbiturates complexes; Inhibition; Monoamine oxidase-B; Rat brain; Thiouracils complexes