PLATELET-AGGREGATION INHIBITING AND ANTICOAGULANT EFFECTS OF OLIGOAMINES .32. ANTIMICROBIAL EFFECTS OF OLIGOAMINES

Twenty-four oligoamines belonging to six (1-6) structurally different types were tested in vitro for their antibacterial activity against 14 different bacterial species comprising a total of 187 strains. Ten co mpounds were able to inhibit growth of at least one strain at concentr ations less than or equal to 10 mu mol/L. For three compounds, minimum inhibitory concentrations for some strains were even below 1 mu mol/L . Clear structure-activity relationships showed that the inhibitory ef fect depended on the bridge connecting the nitrogen atoms, the substit ution of the nitrogens, and the number of nitrogen atoms present in on e molecule. Substitutions like N-4-phenylbutyl, N-octyl, and N-nonyl w ere most active, while short (butyl) and long (dodecyl) substituents d iminished or abolished the activity. The antimicrobial spectrum of the oligoamines tested here covered gram-positive (e.g. Staphylococcus au reus, Listeria monocytogenes, Bacillus subtilis) and gram-negative (e. g. Escherichia coli, Citrobacter spp., Acinetobacter spp.) microorgani sms. The type of action was classified as bactericidal. As the inhibit ion of growth is complete immediately after the addition of the oligoa mines, an interaction with the bacterial cell-membrane is probable.