The rutin/β-cyclodextrin interactions in fully aqueous solution:: spectroscopic studies and biological assays

In the present work the feasibility of beta-cyclodextrincomplexation was explored, as a tool for improving the aqueous solubility and antioxidant efficacy of rutin. By means of H-1 NMR, UV-vis and circular dichroism spectroscopy the single aromatic ring of rutin was found to be inserted into the beta-cyclodextrin cavity to form a 1: 1 inclusion complex. The effect of P-cyclodextrin on the spectral features of rutin was quantitatively investigated. in fully aqueous medium. by holding the concentration of the guest constant and varying the host concentration. The associated binding constants were estimated to be 142 +/- 20 and 153 +/- 20 M-1, respectively, on the basis of the observed UV-vis absorption and circular dichroism intensities. The antioxidant activity of rutin was also investigated. as affected by molecular encapsulation within beta-cyclodextrin (batophenanthroline test; comet assay; lipid peroxidation); the inclusion complex revealed improved antioxidant efficacy that may be in pan explained by an increased solubility in the biological moiety. (C) 2004 Published by Elsevier B.V.