INHIBITORY EFFECTS OF CYCLODEXTRINS BY INCLUSION ON THE CATALYTIC ACTIVITY OF GLYCYRRHIZINATE FOR THE HYDROLYSIS OF A NONIONIC ESTER SURFACTANT

alpha-, beta- and gamma-Cyclodextrins (CyDs) and related derivatives h ave been investigated for their inhibitory effects on the catalytic ac tivity of dipotassium glycyrrhizinate (GK2) in the hydrolysis of polyo xyethylene(60) hydrogenated castor oil, a non-ionic ester surfactant ( HCO-60). The activity of GK2 was found to be completely inhibited in t he presence of an equimolar amount of gamma-CyD owing to the formation of a 1:1 host-guest complex. beta-CyD behaved similarly, However, nei ther inhibition nor complexation was observed in the case of alpha-CyD , Circular dichroic spectroscopy, using the absorption at 340 nm due t o the enone chromophore of GK2, was found to be a useful means to stud y the details of inclusion of GK2 by CyDs.