Abstract |
Complexation of benznidazole (BZL), a drug of choice for the treatment of Chagas neglected disease, with cyclodextrin (CD) derivatives was analyzed by solid-state NMR. C-13 cross polarization/magic angle spinning spectra were recorded from BZL and from BZL:beta-CD, BZL:methyl beta-CD and BZL:hydroxypropyl beta-CD complexes, which were obtained by the solvent evaporation technique. No significant evidence was obtained on BZL inclusion complexes involving either beta-CD or hydroxypropyl beta-CD. Conversely, BZL:methyl beta-CD displayed BZL resonances characteristic of an amorphous drug and data analysis confirmed the presence of stable BZL:methyl beta-CD inclusion complexes, with benzene encapsulated into the host cavity. Further evidences on complex structure and dynamics were obtained from proton and carbon spin-lattice relaxation times in the rotating frame. These data are consistent with a common guest-host spin reservoir. The BZL interaction with methyl beta-CD provided a route to stabilize amorphous BZL. Physical mixtures with identical BZL and CD compositions were also studied for comparison. (C) 2015 Elsevier Ltd. All rights reserved. |