title: Monitoring of antioxidant properties of uric acid in humans for a consideration measuring of levels of allantoin in plasma by liquid chromatography.
abstract: Uric acid is the end product of purine metabolism in humans. It has been pointed out that uric acid acts as an antioxidant and is capable to react with biologically relevant oxidants to form allantoin. Therefore, measurement of allantoin in humans was proposed as a marker of oxidative stress. We estimated allantoin in human plasma obtained from the patients with chronic renal failure before hemodialysis (n=30), patients with non-insulin dependent diabetes mellitus (n=30) and blood donors (n=30) using a method based on selective isolation of allantoin from deproteinized plasma samples on AG 1-X8 resin and its derivatization to glyoxylate-2,4-dinitrophenylhydrazone. The method is free from urate and glyoxylate interferences. Separation of glyoxylate-2,4-dinitrophenylhydrazone from other hydrazones was achieved on reversed phase HPLC with gradient elution and UV/VIS detection at 360 nm. The analytical performance of this method is satisfactory with intra-assay CV 5.7%, inter-assay CV 8.3% and recovery 94.1%. We have determined other parameters of oxidative stress (malondialdehyde, total antioxidant status, superoxide dismutase and glutathione peroxidase) too. The preliminary reference range of allantoin in a group of blood donors is 4.76+/-2.99 micromol/L. In the patients with chronic renal failure and the patients with non-insulin dependent diabetes mellitus we found allantoin levels in plasma (27.1+/-13.8) micromol/L and (11.08+/-5.90) micromol/L, respectively. It seems that allantoin is a possible indicator of free radical damage in vivo.
authors.affiliation: Faculty of Chemical Technology, Department of Biological and Biochemical Sciences, University of Pardubice, Strossova 239, 53003 Pardubice, Czech Republic. roman.kandar@upce.cz
authors.forename: Roman
authors.initials: R
authors.lastname: Kand'ár
authors.forename: Pavla
authors.initials: P
authors.lastname: Záková
authors.forename: Vladimíra
authors.initials: V
authors.lastname: Muzáková
mesh_terms: D000481:Allantoin / Q000097:blood*; D000975:Antioxidants / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D005979:Glutathione Peroxidase / Q000097:blood; D006801:Humans; D018384:Oxidative Stress; D015203:Reproducibility of Results; D013050:Spectrometry, Fluorescence / Q000379:methods; D013482:Superoxide Dismutase / Q000097:blood; D014527:Uric Acid / Q000378:metabolism*
chemical_list: D000975:Antioxidants; D014527:Uric Acid; D000481:Allantoin; D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase