Inclusion Complexes of Coenzyme Q10 with Polyamine‐Modified β‐Cyclodextrins: Characterization, Solubilization, and Inclusion Mode

The inclusion-complexation behavior of coenzyme Q10 (CoQ10) with the three polyamine-modified β-cyclodextrins (CDs) 1–3 was investigated in both solution and the solid state by means of NMR, XRD, and FT-IR spectroscopy. The results showed that the apparent solubility of CoQ10 increased linearly upon addition of hosts 1–3, giving AL-type phase-solubility curves. These hosts 1–3 were able to solubilize CoQ10 to high levels, up to 1.35, 1.52, and 1.44 mg/ml (calculated as CoQ10), respectively. The host 2 with a moderate-length chain is the most suitable for inclusion complexation of CoQ10. Accroding to the ROESY experiments, the MeO groups of CoQ10 and the tether of 2 can be co-included into the cavity of β-CD through the induced-fit interaction between host and guest. The binding ability of modified β-CDs 1–3 upon complexation with CoQ10 are discussed from the viewpoints of the size/shape-matching relationship and the induced-fit concept between host CDs and guest CoQ10 molecule.