γ-Cyclodextrin Inclusion of Phloroglucinol: Solid State Studies and Antioxidant Activity throughout the Digestive Tract

Phloroglucinol is a powerful antioxidant compound and an active pharmaceutical ingredient used in the management of intestinal spasms. In this report, we describe the interaction of gamma-cyclodextrin with phloroglucinol to readily form a solid inclusion compound with 1:1 by co-dissolution and freeze-drying. Solid-state characterisation using FT-IR, thermal analyses (TGA and DTA) and X-ray powder diffraction confirmed the formation of a true inclusion compound (gamma-CD center dot PG) in which the molecules of gamma-CD are stacked into channels. This spatial arrangement is typical of gamma-CD inclusion compounds, and it allows for the guest molecules to be located inside these channels. The evaluation of the antiradical potential of gamma-CD center dot PG (against O-2(center dot)- and NO center dot) on different steps of the digestive process (mouth, gastric and intestinal phases) led us to conclude that the inclusion of phloroglucinol promoted better antioxidant activity at the end of the digestion when compared to the free phloroglucinol.