Electrochemical investigations into host-guest interactions of a natural antioxidant compound with β-cyclodextrin

The electrochemical behavior of mangiferin (MGN), a natural antioxidant compound, is examined using cyclic and differential pulse voltammetry in a protic medium on a glassy carbon electrode. The voltammograms exhibit a single irreversible pH-dependent anodic wave with current controlled by adsorption. Complexes of MGN with beta-cyclodextrin (beta-CD) were prepared and their formation was confirmed by UV-vis spectroscopy and electrochemical experiments, using a self-assembled monolayer of cyclodextrin on a gold electrode. The association constant of MGN:beta-CD complexes was estimated by the Benesi-Hildebrand method, based on the spectrophotometric quantification of free beta-CD and by the direct method using cyclic voltammetry and the Langmuir isotherm. PM IRRAS experiments corroborated the inclusion process based on the observation of the corresponding peaks in the spectra of the samples. MGN was quantified using a simple electrochemical method based on a beta-CD incorporated carbon nanotube (CNT)-modified electrode (beta-CDCNT). The presence of beta-CD led to a 10-fold lower detection limit than that obtained with a CNT-modified electrode. (C) 2010 Elsevier Ltd. All rights reserved.