Study of binary systems of β-cyclodextrin with a highly potential anti-mycobacterial drug

The present research paper is dedicated to the obtaining and physicochemical characterization of a highly potential anti-mycobacterial drug candidate with β-cyclodextrin (βCD). The active substance is a 1,3,4-oxadiazole derivative, 2-phenyl-5-{[(2-phenyl-1,3-dioxolan-2-yl)methyl]sulfanyl}-1,3,4-oxadiazole, further named DIOX. DIOX–βCD binary systems were obtained as a physical mixture and a lyophilized product with molar ratio between the main components equal to 1:1 and 1:2. The obtained systems were submitted to physicochemical characterization applying the following instrumental methods: infrared spectrometry, differential scanning calorimetry, and X-ray crystallographic analysis. Besides, a molecular modeling analysis has been performed. The research data suggested certain intermolecular interaction between DIOX and βCD, suggesting formation of a three-molecular inclusion complex DIOX:βCD, including one DIOX molecule and two molecules of βCD. The main parts of the DIOX molecule included in the hydrophobic cavity of the cyclodextrin molecules most probably are dioxolane cycle and two benzene rings.