possessed high antibacterial activity towards gram-negative bacteria P. aeruginosa (ATCC9027) with the MIC value of 460–555 µM. According to the results of toxicity studies of the compounds to HEK-293, HaCaT, Balb/c 3T3, red blood cells and normal mitogen-activated lymphocytes, three compounds- VP-4556, VP-4604 and VP-4509 - bearing azanorbornene, octahydro-3,5-methanocyclopenta[b]pyrrole and bio-isosteric