title: Production of uremic toxin methylguanidine from creatinine via creatol on activated carbon.
abstract: The mixture of creatinine, activated charcoal and water was stirred. As a result the conversion of creatinine into two products was observed. (1)H, (13)C NMR and HMBC spectra were recorded and the chemical shifts assigned. Two uremic toxins: creatol and N-methylguanidine were identified. To interpret the NMR data obtained, the optimum structure of creatol, which can exist in the forms of seven tautomers, has been calculated using the DFT B3LYP/6-311G(2d,p) method. The influence of the solvent was described by the polarizable continuum model (PCM). The calculated energy of the most energetically stable tautomeric form A is lower by 12.2, 16.9, 33.8, 81.5, 106.3, 130.4kJ/mol in water than that of the tautomers B-G, respectively, which suggests that the A form of creatol should prevail in solution. In DMSO, the calculated energy of the most energetically stable tautomeric form A is lower than that of both D and B and the remaining tautomeric forms (C, E-G) are less energetically stable. Subsequently, we sought the correlations between the experimental and the calculated chemical shifts of protons and carbons-13 for the forms -A, B (in water) and A, B, D (in DMSO) - of creatol. The population of the A tautomer is predominant in both H(2)O and DMSO. We have also recorded the spectra of creatol and N-methylguanidine at different pH. Our data are complete enough to be used in the analysis of body fluids.
authors.affiliation: Faculty of Chemistry, Warsaw University of Technology, Warsaw, Poland. hkraw@ch.pw.edu.pl
authors.forename: Hanna
authors.initials: H
authors.lastname: Krawczyk
mesh_terms: D002606:Charcoal / Q000737:chemistry*; D003404:Creatinine / Q000031:analogs & derivatives* / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007202:Indicators and Reagents; D009682:Magnetic Resonance Spectroscopy; D008760:Methylguanidine / Q000138:chemical synthesis* / Q000633:toxicity; D012997:Solvents; D014511:Uremia / Q000139:chemically induced*
chemical_list: D007202:Indicators and Reagents; D012997:Solvents; C064402:creatol; D002606:Charcoal; D008760:Methylguanidine; D003404:Creatinine