Cucurbit[7]uril (CB[7]) has recently attracted increasing attention in pharmaceutical sciences due to its great potential in improving the physicochemical properties and bioactivity of drug molecules. Herein, we have investigated the influence of CB[7]'s complexation on the solubility, antimycobacterial activity, and cardiotoxicity of a model anti-tuberculosis drug, clofazimine (CFZ), that has poor water-solubility and inherent cardiotoxicity. In our study, CFZ was found to be complexed by CB[7], in a 1 : 1 binding mode with a relatively strong binding affinity (in the order of magnitude of 10(4)-10(5) M(-1)), as determined by the phase solubility method via HPLC-UV analysis and (1)H NMR titration, as well as UV-visible spectroscopic titration, and further confirmed by electrospray ionization mass spectrometry (ESI-MS). Upon complexation, the solubility of virtually insoluble CFZ was significantly increased, reaching a concentration of up to approximately 0.53-fold of the maximum solubility of CB[7]. The inherent cardiotoxicity of CFZ was dramatically reduced to almost nil in the presence of CB[7]. Importantly, on the other hand, such a supramolecular complexation of the drug did not compromise its therapeutic efficacy, as shown by the antimycobacterial activities examined against Mycobacterium smegmatis, demonstrating the significant potential of CB[7] as a functional pharmaceutical excipient.

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Cucurbit [7]uril (CB [7]) was found in vitro to sequester the neurotoxins MPTP (N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) and MPP + (N-methyl-4-phenylpyridine). The CB [7]/neurotoxin host−guest complexes were studied in detail with 1 H NMR, electrospray ionization mass spectrometry, UV− visible spectroscopic titration, and molecular modeling by density functional theory. The results supported the macrocyclic encapsulation of MPTP and MPP + , respectively, by CB [7] in aqueous solutions with relatively strong affinities and 1:1 host− guest binding stoichiometries in both cases. More importantly, the progression of MPTP/MPP + induced neurodegeneration (often referred to as a Parkinson's disease model) was observed to be strongly inhibited in vivo by the synthetic CB [7] receptor, as shown in zebrafish models. These results show that a supramolecular approach could lead to a new preventive and/or therapeutic strategy for counteracting the deleterious effects of some neurotoxins leading to neurodegeneration.