Antibacterial activity of venom alkaloids from the imported fire ant, Solenopsis invicta Buren

The antibacterial properties of synthetic fire ant venom alkaloids were tested by disc-diffusion procedures against a variety of bacteria and by doubling concentrations in broth cultures of Staphylococcus aureus and Escherichia coli. Gram-positive bacteria were inhibited by lower concentrations of trans-2-methyl-6-n-undecylpiperidine, trans-2-methyl-6-n-tridecylpiperidine, and trans-2-methyl-6-n-pentadecylpiperidine than were gram-negative bacteria. A fourth alkaloid, trans-2-methyl-6-(cis-6-pentadecenyl)piperidine, which was available in minute quantity and was tested by disc-diffusion only, was ineffective against all organisms.