title: Solvent-dependent conformational system of hydroxyureas in octanol-water and in inhibition of ribonucleotide reductase.
abstract: The carbonyl nitrogen IR absorption region of selected hydroxyureas was examined in octanol. The spectra indicated appreciably different absorptions prior to and after equilibration with water. Stability studies on the hydroxyureas indicated that the absorption differences were not due to chemical decomposition in the equilibration process but were due to solvent conformation and/or tautomeric dependency of the system. Preliminary in vitro inhibition of the enzyme ribonucleoside diphosphate reductase by selected hydroxyureas also indicated an apparent solvent dependency, which may involve the conformational and/or tautomeric properties of these agents. The implications of the solvent-dependent conformation-tautomeric system observed are discussed in relation to this property in the biological action of these agents.
mesh_terms: D055598:Chemical Phenomena; D002627:Chemistry, Physical; D004355:Drug Stability; D006918:Hydroxyurea / Q000031:analogs & derivatives* / Q000494:pharmacology; D008968:Molecular Conformation; D000442:Octanols; D012264:Ribonucleotide Reductases / Q000037:antagonists & inhibitors*; D012997:Solvents; D013055:Spectrophotometry, Infrared; D013997:Time Factors; D014867:Water
chemical_list: D000442:Octanols; D012997:Solvents; D014867:Water; D012264:Ribonucleotide Reductases; D006918:Hydroxyurea