Influences on shift of pKa, solubility and antifungal activity of fuberidazole by inclusion complexation with cucurbit[n]urils

Abstract

Interaction between cucurbit[n]uril (Q[n], n=6, 7, 8) and fuberidazole (FBZ) in HCl solution at pH 2.5 was investigated by UV-Vis spectroscopy, ITC, 1H NMR spectroscopy. The shift of pKa and bioactivities against Fusarium graminearum about fuberidazole and its host-guest inclusion complexes were discussed. The results showed that the inclusion complexes between cucurbit[n]urils and fuberidazole were formed, and the corresponding pKa of complexes have shifted. In addition, complexation by Q[n] (n=6, 7, 8) has proven to cause solubility enhancement. The activity experimental results showed that complexation of fuberidazole with Q[n] (n=6, 7) recedes activity against Fusarium graminearum while with Q[8] enhances the activity against Fusarium graminearum in vivo.