title: Inclusion complexes of pyrimethamine in 2-hydroxypropyl-beta-cyclodextrin: characterization, phase solubility and molecular modelling.
abstract: The inclusion complexation of pyrimethamine in 2-hydroxypropyl-beta-cyclodextrin has been investigated by 2D (1)H NMR, FTIR and UV/visible spectroscopy and also by molecular modelling methods (AM1, PM3, MM3). From the phase-solubility diagram a linear increase was observed in pyrimethamine aqueous solubility in the presence of 2-hydroxypropyl-beta-cyclodextrin, evidencing the formation of a soluble inclusion complex. According to the continuous variation method (Job's plot) applied to fluorescence measurements, a 1:1 stoichiometry has been proposed for the complex. Concerning the structure of the complex, a Cl-in orientation of pyrimethamine in the 2-hydroxypropyl-beta-cyclodextrin cavity has been proposed from the theoretical calculations, being confirmed by two-dimensional (1)H NMR spectroscopy (ROESY). The thermal behaviour has also been studied, providing complementary evidences of complex formation.
authors.affiliation: Departamento de Química, Universidade Federal de Sergipe (UFS), Av Marechal Rondon s/n, Campus Universitário Prof. José Aloísio de Campos, CEP 491000-000, São Cristóvão, SE, Brazil.
authors.forename: Márcia Valéria Gaspar
authors.initials: MV
authors.lastname: de Araújo
authors.forename: Elze Kelly Barbosa
authors.initials: EK
authors.lastname: Vieira
authors.forename: Gilderman Silva
authors.initials: GS
authors.lastname: Lázaro
authors.forename: Leila
authors.initials: L
authors.lastname: de Souza Conegero
authors.forename: Odair Pastor
authors.initials: OP
authors.lastname: Ferreira
authors.forename: Lui S Eduardo
authors.initials: LS
authors.lastname: Almeida
authors.forename: Ledjane Silva
authors.initials: LS
authors.lastname: Barreto
authors.forename: Nivan Bezerra
authors.initials: NB
authors.lastname: da Costa
authors.forename: Iara F
authors.initials: IF
authors.lastname: Gimenez
mesh_terms: D000073738:2-Hydroxypropyl-beta-cyclodextrin; D002152:Calorimetry, Differential Scanning; D008958:Models, Molecular; D015394:Molecular Structure; D011739:Pyrimethamine / Q000737:chemistry*; D012995:Solubility; D013053:Spectrophotometry; D013818:Thermogravimetry; D014961:X-Ray Diffraction; D047392:beta-Cyclodextrins / Q000737:chemistry*
chemical_list: D047392:beta-Cyclodextrins; D000073738:2-Hydroxypropyl-beta-cyclodextrin; D011739:Pyrimethamine