Characterization, solubility and antibacterial activity of inclusion complex of questin with hydroxypropyl-β-cyclodextrin.

To increase the water solubility of questin and broaden its application in preventing and treating Vibrio diseases in aquaculture, an inclusion complex of questin with 2-hydroxypropyl-β-cyclodextrin (HP-β-CD) was prepared by stirring and coevaporation strategy. The results of thin-layer chromatography and nuclear magnetic resonance spectrum confirmed the inclusion of questin into HP-β-CD. The aqueous solubility of questin in the inclusion complex reached (62.63 ± 1.21) µg/mL, which was 110 times of questin's original solubility. The preliminary agar diffusion method indicated that questin-HP-β-CD inclusion complex showed enhanced antibacterial activity against Vibrio harveyi compared with free questin. This finding provided a reliable basis for the further application of questin as aquatic antibacterial agent.