title: Complexation of clofazimine by macrocyclic cucurbit[7]uril reduced its cardiotoxicity without affecting the antimycobacterial efficacy.
abstract: 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.
authors.affiliation: State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Taipa, Macau SAR, China. rwang@umac.mo.
authors.forename: Shengke
authors.initials: S
authors.lastname: Li
authors.forename: Judy Yuet-Wa
authors.initials: JY
authors.lastname: Chan
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.forename: David
authors.initials: D
authors.lastname: Bardelang
authors.forename: Jun
authors.initials: J
authors.lastname: Zheng
authors.forename: Wing Wai
authors.initials: WW
authors.lastname: Yew
authors.forename: Denise Pui-Chung
authors.initials: DP
authors.lastname: Chan
authors.forename: Simon Ming Yuen
authors.initials: SM
authors.lastname: Lee
authors.forename: Ruibing
authors.initials: R
authors.lastname: Wang
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D001952:Bridged-Ring Compounds / Q000737:chemistry / Q000494:pharmacology*; D002991:Clofazimine / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D006339:Heart Rate / Q000187:drug effects; D007093:Imidazoles / Q000737:chemistry / Q000494:pharmacology*; D047028:Macrocyclic Compounds / Q000737:chemistry / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D015394:Molecular Structure; D020102:Mycobacterium smegmatis / Q000187:drug effects*; D020521:Stroke / Q000188:drug therapy; D013329:Structure-Activity Relationship; D015027:Zebrafish; D000099246:Cucurbit(n)urils
chemical_list: D000900:Anti-Bacterial Agents; D001952:Bridged-Ring Compounds; D002991:Clofazimine; D007093:Imidazoles; D047028:Macrocyclic Compounds; C456276:cucurbit(7)uril; D000099246:Cucurbit(n)urils