Molecular encapsulation of histamine H2-Receptor antagonists by cucurbit[7]Uril: An experimental and computational study

Abstract

The histamine H2 -receptor antagonists cimetidine, famotidine and nizatidine are individually encapsulated by macrocyclic cucurbit[7]uril (CB[7]), with binding affinities of 6.57 (±0.19) × 103 M-1 , 1.30 (±0.27) × 104 M-1 and 1.05 (±0.33) × 105 M-1 , respectively. These 1:1 host-guest inclusion complexes have been experimentally examined by 1H-NMR, UV-visible spectroscopic titrations (including Job plots), electrospray ionization mass spectrometry (ESI-MS), and isothermal titration calorimetry (ITC), as well as theoretically by molecular dynamics (MD) computation. This study may provide important insights on the supramolecular formulation of H2 -receptor antagonist drugs for potentially enhanced stability and controlled release based on different binding strengths of these host-guest complexes.