Inclusion Complexation of Prostaglandin F2α with α-and β-Cyclodextrins in Aqueous Solution

The interaction of prostaglandin F2α (PGF2α) with α-and β-cyclodextrins in aqueous solution was investigated by potentiometric titration, solubility, and carbon 13 nuclear magnetic resonance (13C NMR) techniques. Changes in titration curve and solubility of PGF2α following the binding to α-and β-cyclodextrins were quantitatively treated to obtain equilibrium constants and thermodynamic parameters. The protolytic dissociation of PGF2α was significantly suppressed by inclusion complexation. 13C NMR chemical shift changes suggested that binding of PGF2α to α-cyclodextrin was somewhat different from that to β-cyclodextrin.