Investigation of the complexation of (+)-catechin by beta-cyclodextrin by a combination of NMR, microcalorimetry and molecular modeling techniques.

(+)-Catechin is a polyphenolic compound of natural origin that presents anti-oxidant properties of interest for therapeutics or cosmetics uses. Preliminary studies on inclusion into cyclodextrin cavities yielded contradictory results both for the quantitative (affinity constant) and qualitative description of the interaction. By a combination of several experimental and theoretical methods, the present study resolved the previous ambiguities about the interaction between (+)-catechin and beta-cyclodextrin. Thermodynamic data measured by isothermal titration calorimetry demonstrate that the binding is enthalpy driven. Excellent agreement has been obtained for the measurement of the association constant by NMR and microcalorimetry. The several docking modes obtained by systematic docking studies have been compared to intermolecular contacts measured by NMR and the overall geometry of the complex can be proposed.