Ionophorous Properties of Antibiotic-6016, a Novel Magnesium Selective Ionophore

Abstract

The cation selectivity profile of a new monocarboxylic ionophore, antibiotic-6016 has been investigated by measuring the complexation affinities for metal cations and biogenic amines as well as the cation transport activity across an organic solvent barrier.
In a two phase partition study the antibiotic formed the complexes with divalent cations of 2:1 stoichiometry and the cation selectivity sequence are summarized as: Mg²⁺>Mn²⁺_??_Ca²⁺>Sr²⁺_??_Ba²⁺. The antibiotic was also able to complex with monovalent cations of 1:1 ionophore: cation⁺ stoichiometry and the complexation affinity was ranked as: NH₄⁺_??_K⁺>Rb⁺_??_Na⁺>Li_??_Cs⁺.
It is noteworthy that the antibiotic was able to complex with serotonin but was negligible for norepinephrine and histamine. In the bulk cation transport system, it efficiently trans-ported Na⁺, K⁺, Ca²⁺, Ba²⁺ and Rb⁺ through an CCl₄ barrier layer but failed to transport Cs+ and biogenic amines.
It is of great interest that the antibiotic is characterized for first time as a broad cation spectrum ionophore with a remarkable preference for Mg²⁺ in the naturally occurring polyether antibiotics.