The in vitro antioxidant properties of the Al-quercetin/βCD and Al-catechin/βCD inclusion compounds, rationalized in terms of their electrochemical behaviour

Inclusion compounds of Al-quercetin and Al-catechin complexes with β-cyclodextrin (βCD) were investigated. The complex and the inclusion compound of quercetin are more effective DPPH^? scavengers than the corresponding catechin compounds and the inclusion does not compromise their scavenging abilities, with only a slight decrease in the EC₅₀ values. This is in accordance with the electrochemical data, which revealed that the inclusion compounds have lower diffusion coefficients in aqueous solution than the non-included compounds. For the quercetin compounds, some spectroscopic properties were also addressed by means of UV–visible and NMR measurements in aqueous media.