Étude comparée de trois antibiotiques ionophores: X.537 A (lasalocide), A.23187 (calcimycine) et X.14547 A. Complexation des cations IA et IIA, transport de Ca++

Abstract

Using a potentiometric method, both the stoechiometry and the stability of complexes formed in methanol between the three natural ionophores and cations IA and IIA have been obtained. With alkali metal ions, neutral complexes of stoechiometry 1:1 for X.537 A and A.23187, 2:1 for X.14547 A are formed. Complexes of higher stability are obtained with alkaline-earth cations, corresponding to two types of association; 1:1 charged and 2:1 neutral. A.23187 and X.14547 A show similar behaviour as far as the sequence of formation of these two complexes is concerned, but the stability constants are higher for the first one. For X.537 A, the existence of a 2:1 complex is not detectable by our method, except for magnesium.Calcium transport by these ionophores through a cell such as: aqueous phase/chloroformic phase/aqueous phase has also been studied. An attempt is made to relate ionic fluxes to the preceding equilibrium constants.