Antibacterial activities of new synthetic divalent cation chelators

A series of new synthetic ligand compounds which chelate divalent cations w as examined for the antibacterial activities of the compounds. Only 2 of 14 synthetic chelators, 9-trans-anthryl-1, 4, 8, 11-tetraazatetradecane (No. 6) and bis(2-pyridyl)methylamine (No. 13) showed antibacterial activities, whereas none of the diamines, hydrophilic triamines nor tetramines showed a ntibacterial activities. Chelators No. 6 and No. 13 inhibited the growth of both Gram-negative and -positive bacteria at doses of 25-200 mu g/ml, comp arable to those of common antibiotics such as polymixin B, fosfomycin and m acrolides. Ethylenediaminetetraacetate (EDTA) potentiated these antibacteri al activities, whereas an inhibitory effect of Mg2+ on the MICs of these ch elators was observed. Moreover, these chelators enhanced the leakage of per iplasmic beta-lactamase, It is therefore suggested that chelators No. 6 and No. 13 disrupt both the membranes and cytoplasmic functions of bacteria, r esulting in cell death.