A Study of b-Cyclodextrin Inclusion Complexes with Progesterone and Hydrocortisone Using Rotating Frame Overhauser Spectroscopy

Summary. Inclusion complexes of β-cyclodextrin with two steroid derivatives, progesterone (pregn-4-ene-3,20-dione) and hydrocortisone (11,17,21-trihydroxy-pregn-4-ene-3,20-dione), were studied in the liquid state by NMR spectroscopy. The complex formation process was monitored by intermolecular dipolar interactions between 1 H signals in the hydrophobic β-cyclodextrin cavity (H-3 and H-5 of the α-glucose units) and the steroid moiety in ROESY spectra. The data revealed that progesterone is fully immersed in the β-cyclodextrin cavity; however, complete inclusion of the hydrocortisone molecule was prevented by the polar hydroxyl groups on its surface.