1H-NMR study of suloctidil-A23187 calcium ionophore interaction

Suloctidil is a molecule with calcium antagonist properties, whose anti-ionophoretic effect has previously been reported. In the presence of A23187 calcium ionophore free acid (A+), the NMR spectra of suloctidil (S +/-) are modified at the level of H-1 protons and to a lesser degree in the CH3-3 and aromatic regions. Experiments with one of the enantiomers of suloctidil and decoupling investigations led us to postulate the existence of diastereoisomers S+/A+, S-/A+ in the suloctidil +/-/A23187 + mixture. Moreover our results allow the hypothesis that suloctidil and calcium compete for the same binding site of the ionophore molecule.