title: Increased plasma homocysteine and allantoin levels in coronary artery disease: possible link between homocysteine and uric acid oxidation.
abstract: OBJECTIVE
  Homocysteine increases the damage to the cardiovascular system in different ways, one of them is the formation of reactive oxygen species resulting from the auto-oxidation of homocysteine. At the same time, uric acid is one of the major antioxidants in the plasma and protects the cells towards increased ROS activity. In humans, allantoin is only formed from non-enzymatic oxidation of uric acid by free radicals. We aimed to determine the levels of homocysteine, uric acid and allontoin in patients with coronary artery diseases, and to evaluate the possible correlation between homocysteine and allantoin.
  
  
  RESULTS
  Plasma total homocysteine, uric acid and allantoin levels of 50 patients with coronary artery diseases and 23 healthy controls were determined by HPLC methods. Commercial diagnostic kits were used for the determination of other biochemical parameters. We obtained higher homocysteine, uric acid and allantoin levels in patients than in controls (p < 0.0001). Homocysteine levels were positively correlated with uric acid (r = 0.435, p < 0.0001) and allantoin (r = 0.583, p < 0.0001) levels in the whole study population. This correlation was persistent between allantoin and homocysteine after adjustment of these parameters for age, sex and creatinine. We accepted 15.0 micromol/l as a cut-off value between normal and mildly elevated homocysteine levels for patients and controls. Twenty-five patients showed moderate hyperhomocysteinaemia. The mean allantoin and uric acid values of the moderate hyperhomocysteinaemic group were significantly higher than that of the group having lower homocysteine levels than this cut-off value (p < 0.0001 for allantoin, p < 0.02 for uric acid).
  
  
  CONCLUSIONS
  Results imply that there is increased allantoin production resulting from uric acid oxidation by free radicals in hyperhomocysteinaemic patients with coronary artery disease. The possible significance of the relationship between homocysteine and allantoin warrants further study.
authors.affiliation: Gazi University, Faculty of Pharmacy, Department of Biochemistry, Etiler, Ankara, Turkey. yesim@gazi.edu.tr
authors.forename: Yeşim
authors.initials: Y
authors.lastname: Ozkan
authors.forename: Sevgi
authors.initials: S
authors.lastname: Yardim-Akaydin
authors.forename: Ersin
authors.initials: E
authors.lastname: Imren
authors.forename: Meral
authors.initials: M
authors.lastname: Torun
authors.forename: Bolkan
authors.initials: B
authors.lastname: Simşek
mesh_terms: D000328:Adult; D000368:Aged; D000481:Allantoin / Q000097:blood*; D003324:Coronary Artery Disease / Q000097:blood*; D005260:Female; D006710:Homocysteine / Q000097:blood*; D006711:Homocystine / Q000097:blood*; D006801:Humans; D020138:Hyperhomocysteinemia / Q000097:blood*; D008297:Male; D008875:Middle Aged; D010084:Oxidation-Reduction; D017382:Reactive Oxygen Species / Q000378:metabolism; D014527:Uric Acid / Q000097:blood*
chemical_list: D017382:Reactive Oxygen Species; D006710:Homocysteine; D014527:Uric Acid; D000481:Allantoin; D006711:Homocystine