title: Quantum mechanical study and nuclear magnetic resonance measurements of some alpha-arylcarboxyalkyl acids as anti-inflammatory agents.
abstract: The CNDO/2 quantum mechanical conformation method of analysis, charge density and protonation energy calculations, as well as 13C and 1H NMR measurements were carried out for ibufenac, ibuprofen, methylibuprofen, and for a series of alpha-arylpropionic acids. It was found that the nature of the terminal lipophilic residue does not significantly influence the conformation of the alpha-arylcarboxyalkyl acid side chain. The preferred conformational angle, for the torsion of the phenyl-C alpha bond, was found to be 90, 120, and 180 degrees in ibufenac, ibuprofen, and methylibuprofen, respectively. This conformational angle is calculated to be the same in all the alpha-arylpropionic acids. The protonation energies of the alpha-arylpropionic acids are correlated with the anti-inflammatory activity. It was found that the smaller the protonation energy, the larger the anti-inflammatory activity.
authors.affiliation: Instituto de Estructura de la Materia, C.S.I.C. Madrid, Spain.
authors.forename: Y G
authors.initials: YG
authors.lastname: Smeyers
authors.forename: A
authors.initials: A
authors.lastname: Hernandez-Laguna
authors.forename: C
authors.initials: C
authors.lastname: Munoz-Caro
authors.forename: J
authors.initials: J
authors.lastname: Aguilera
authors.forename: E
authors.initials: E
authors.lastname: Galvez-Ruano
authors.forename: M S
authors.initials: MS
authors.lastname: Arias-Perez
mesh_terms: D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000032:analysis*; D002264:Carboxylic Acids / Q000032:analysis; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D011422:Propionates / Q000032:analysis; D011789:Quantum Theory
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D002264:Carboxylic Acids; D011422:Propionates