Fluorimetric and mass spectrometric study of the interaction of β-cyclodextrin and osthole

The inclusion complex of β-cyclodextrin (β-CD) and osthole was studied by the electrospray ionization mass spectrometry (ESI-MS) and fluorescence spectrometry. From the mass spectrum, the 1:1 stoichiometric inclusion complex of β-CD and osthole was observed. The tandem mass spectrum was performed. The fluorescence intensity of osthole increased in the present of β-CD. According to the 1:1 β-CD–osthole mode, the dissociation constant (KD) was obtained by ESI-MS and fluorescence spectrometry. The KD of β-CD–osthole inclusion complex is 6.96 × 10−3 mol L−1 obtained by mass spectrometry and that is 8.14 × 10−3 mol L−1 obtained by fluorescence spectrometry, which is consistent with each other.