title: Spectroscopic characterization of the inclusion complexes of luteolin with native and derivatized beta-cyclodextrin.
abstract: The inclusion complexes of Luteolin (LU) with cyclodextrins (CDs) including beta-cyclodextrin (betaCD), hydroxypropyl-beta-cyclodextrin (HPbetaCD) and dimethyl-beta-cyclodextrin (DMbetaCD), Scheme 1, have been investigated using the method of steady-state fluorescence. The stoichiometric ratio of the three complexes was found to be 1:1 and the stability constants (K) were estimated from spectrofluorometric titrations, as well as the thermodynamic parameters. Maximum inclusion ability was obtained in the case of HPbetaCD followed by DMbetaCD and betaCD. Moreover, 1H NMR and 2D NMR were carried out, revealing that LU has different form of inclusion which is in agreement with molecular modeling studies. These models confirm that when LU-betaCD and LU-DMbetaCD complexes are formed, the B-ring is oriented toward the primary rim; however, for LU-HPbetaCD complex this ring is oriented toward the secondary rim. The ESR results showed that the antioxidant activity of luteolin was the order LU-HPbetaCD>LU-DMbetaCD>LU-betaCD>LU, hence the LU-complexes behave are better antioxidants than luteolin free.
authors.affiliation: Departamento Química Orgánica y Fisicoquímica, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Chile. c.jullian@uchile.cl
authors.forename: Carolina
authors.initials: C
authors.lastname: Jullian
authors.forename: Constanza
authors.initials: C
authors.lastname: Cifuentes
authors.forename: Muriel
authors.initials: M
authors.lastname: Alfaro
authors.forename: Sebastián
authors.initials: S
authors.lastname: Miranda
authors.forename: Germán
authors.initials: G
authors.lastname: Barriga
authors.forename: Claudio
authors.initials: C
authors.lastname: Olea-Azar
mesh_terms: D047311:Luteolin / Q000737:chemistry*; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular; D047392:beta-Cyclodextrins / Q000737:chemistry*
chemical_list: D047392:beta-Cyclodextrins; D047311:Luteolin