Effect of beta-Cyclodextrin on Spectroscopic Propierties of Ochratoxin A in Aqueous Solution

Ochratoxin A (OTA) is a nephrotoxic mycotoxin produced by several fungal species, mainly Aspergillus ochraceus, A. carbonarius and Penicillium verrucosum. It contaminates many foodstuffs, particularly cereals and their derivatives, coffee, beer, wine and cocoa, and represents a serious health threat both to humans and animals. Spectroscopic properties of OTA solutions depend on the pH, solvent polarity and can be influenced by the presence of cyclodextrins (CDs). In this work, the effect of beta-CD on spectroscopic properties of OTA in aqueous solutions has been investigated by means of absorption and steady-state fluorescence at different pHs (range 3.5-9.5). Binding constants of OTA/beta-CD inclusion complexes have been determined by applying modified Benesi-Hildebrand equation. A 1:1 stoichiometry of OTA/beta-CD complexes has been observed at all tested pHs.