Interaction between cyclodextrins and aflatoxins Q1, M1 and P1 -: Fluorescence and chromatographic studies

The fluorescence properties of the aflatoxins M-1, Q(1), P-1 in solution and the effect of various cyclodextrins (alpha-, beta-, gamma-, hydroxypropyl-beta- and alpha-beta-heptakis-di-O-methyl-beta-) on their fluorescence emission were studied. Among the aflatoxins, a substantial enhancement of the fluorescence emission of aflatoxin Q(1) in the presence of aqueous solutions of alpha-, beta-, hydroxypropyl-beta, and alpha-beta-heptakis-di-O-methyl-beta-cyclodextrin was observed. On the contrary, gamma-cyclodextrin proved to be inefficient to enhance the fluorescence properties of this compound. No important fluorescence enhancement was found for aflatoxins P-1 or M-1 for any of the cyclodextrin derivatives tested. The complex formation constant (K-f) of these compounds with beta-cyclodextrin was chromatographically determined, and from the results obtained, we can conclude that K-f cannot be used alone to explain the fluorescence increase. Thermodynamic studies showed that Delta H and Delta S parameters, associated with the partition of aflatoxins in RP-HPLC, increased when beta-cyclodextrin was added to the eluent. (C) 1998 Elsevier Science B.V. All rights reserved.