Complexation of quercetin with three kinds of cyclodextrins: an antioxidant study.
The slightly water-soluble flavonoid quercetin (QUE) and its inclusion with either beta-cyclodextrin (betaCD), hydroxypropyl-beta-cyclodextrin (HP-betaCD) or sulfobutyl ether-beta-cyclodextrin (SBE-betaCD) were investigated. The stoichiometric ratios and stability constants describing the extent of formation of the complexes have been determined by phase-solubility measurements; in all cases type-A(L) diagrams have been obtained (soluble 1:1 complexes). The results showed that the inclusion ability of betaCD and its derivatives was the order: SBE-betaCD>HP-betaCD>betaCD. Kinetic studies of DPPH with QUE and CDs complexes were done. The results obtained indicated that the QUE-SBE-betaCD complex was the most reactive form. The scavenging capability of QUE and CDs complexes with DPPH and galvinoxyl was studied using ESR spectroscopy. All complexes showed a higher scavenging capability with both radicals, compare quercetin in water. Beside, these results indicated that the complexes formed maintained the quercetin antioxidant activity.
Jullian
Carolina
C
Departamento de Química Orgánica y Fisicoquímica, Universidad de Chile, Casilla 233, Santiago 1, Chile. cjullian@uchile.cl
Moyano
Lorena
L
Yañez
Claudia
C
Olea-Azar
Claudio
C
D000975:Antioxidants / Q000737:chemistry*; D001713:Biphenyl Compounds; D003505:Cyclodextrins / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D016166:Free Radical Scavengers; D006834:Hydrazines; D010851:Picrates; D011794:Quercetin / Q000737:chemistry*; D012995:Solubility; D013053:Spectrophotometry
D000975:Antioxidants; D001713:Biphenyl Compounds; D003505:Cyclodextrins; D016166:Free Radical Scavengers; D006834:Hydrazines; D010851:Picrates; D011794:Quercetin; C004931:1,1-diphenyl-2-picrylhydrazyl