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Abstract: The formation of the complexes of Wogonin with β-cyclodextrin (β-CD) and hydroxypropyl-cyclodextrin (HP-β-CD) was studied by fluorescence spectra and nuclear magnetic resonance spectroscopy (NMR). The formation constants (Ks) of complexes were determined by fluorescence method. The results suggested that HP-β-CD was easier to form inclusion with Wogonin than β-CD in solution. In different pH solutions, CDs have different inclusive capacity to Wo. β-CD was most suitable for inclusion of neutral form and HP-β-CD was suitable for acidic form. In addition, the experimental resulted confirmed the existence of 1:1 inclusion complex of Wogonin with CDs. Besides, kinetic studies of DPPHonin and CDs complexes were done. The results obtained indicated that the complex was the most reactive form. Special configuration of complex has been proposed on NMR technique. [Copyright &y& Elsevier]

The inclusion complexation behaviour of ferulic acid (FA) with β-cyclodextrin (β-CD) and hydroxypropyl-β-cyclodextrin (HP-β-CD) was investigated by UV-vis, fluorescence and 1H NMR spectroscopy. Since the guest may exist in either anionic or neutral form, the experiments were performed at different pH values. The stoichiometry and association constants of the complexes were determined by nonlinear regression analysis. The phase-solubility studies indicated that the water solubility of FA was improved through complexation with β-CD and HP-β-CD. An increase in the antioxidant reactivity was observed when inclusion complexes that FA formed with CDs were studied. Based on the NMR data, the spatial configurations of FA/β-CD and FA/HP-β-CD complexes were proposed, which suggested that FA entered into the cavity of β-CD from the narrow side, with the lipophilic aromatic ring and ethylenic moieties inside the CD cavity, and the -COOH group was close to the wider rim and exposed outside the cavity. A theoretical study of the complexes using molecular modelling gives the results in good agreement with the NMR data. [ABSTRACT FROM AUTHOR]

Abstract: The formation of the complexes of BG with β-CD and HP-β-CD was studied by UV–vis absorption spectroscopy, fluorescence spectra, Phase-solubility measurements and nuclear magnetic resonance spectroscopy (NMR) in solution. The formation constants (K) of complexes were determined by fluorescence method and Phase-solubility measurements. The results showed that the inclusion ability of β-CD and its derivatives was the order: HP-β-CD>β-CD. In addition, the experimental resulted confirmed the existence of 1:1 inclusion complex of BG with CDs. The antioxidant ability studies of BG and CDs complexes were done. The results obtained indicated that the BG/HP-β-CD complex was the most reactive form, and then was the BG/β-CD complex; the last was BG. Special configuration of complex has been proposed on NMR technique. [Copyright &y& Elsevier]