1H and 13C NMR Structural Studies of Amiloride in Cryosolvents

Amiloride hydrochloride is a potent inhibitor of several cellular ion transport systems and has been used as a diuretic drug and a probe of ion transport processes. ¹H and ¹³C NMR studies have been carried out at a proton field strength of 400 MHz in DMSO/CH₂Cl₂ and DMF cryosolvents over a temperature range from 20 to –55°C in order to investigate the conformations of the hydrochloride and its free-base form in solution. Resonances for all protons have been assigned. The results of double resonance and NOE experiments suggest that the structures in solution are most likely planar and consistent with previously reported computational results.