Complexation of several benzimidazole-type fungicides with alpha- and beta-cyclodextrins

The potential increase in water solubility of three benzimidazole-type fungicides (thiabendazole, carbendazim, and fuberidazole) due to complexation with alpha- and beta-cyclodextrins was investigated. Fluorescence emission spectra of the fungicides in the presence of different concentrations of the cyclodextrins were measured. Analysis of these spectra by the method of principal components global analysis (PCGA) yielded precise values for the association constants and the emission spectra of the fungicide-cyclodextrin inclusion complexes. Phase-solubility diagrams confirmed the formation of inclusion complexes between each of the fungicides and beta-cyclodextrin and showed significant increases of their solubilities due to complexation.