Drugs discovery process includes the following stages: selection of disease, selection of drug target, identifying biological test, discovery of model compound. One of in vivo tests applied in this context is antibacterial activity testing. In this paper, the antibacterial activity of 12 newly synthesized compounds was tested against 4 species of bacteria: S. aureus (G+), E. faecalis (G+), M. catarrhalis (G-), E. coli (G-, hypersensitive strain without efflux pumps). On this occasion, microdilution method was applied, which is implemented using microtiter plates. The tested compounds were added to a medium inoculated by certain species of bacteria and then sequentially diluted. The synthesized compounds are derivatives of itaconic acid and anti-malarial drugs: primaquine, chloroquine and mefloquine, as well as the derivatives of itaconic acid and fluoroaniline, pyridine and indole. Although no antibacterial activity is envisaged for these compounds, it is important to conduct extensive in vitro and in vivo testing of potential new drugs, since in this way it is possible to detect new, unforeseen effects. The examined itaconic acid derivatives did not show growth inhibition effect on gram-positive bacteria S. aureus and E. faecalis, or on gram-negative bacteria E. coli. The examined compounds showed substantial growth inhibition effect on the gram-negative bacteria M. catarrhalis. The most potent compound is the already existing anti malaria drug MQ (mefloquine) with the minimum inhibitory concentration of 1/0.5 μg/mL. Out of the newly-synthesized compounds, V9 (MIC = 4 μg/mL) compound showed the best bacterial growth inhibition effect. Minimum inhibitory compound concentrations are related to their lipophilicity. Upon selecting logP as one of lipophilicity parameters, it was evident that antibacterial effect of the compounds on M. catarrhalis increased with the increase in the logP value. The reason for this is the hydrophobicity of bacterial membrane due to the presence of lipooligosaccharides. The compounds showed no effect on E. coli, although even that bacteria species has lipopolysaccharides present in the outer membrane, however as they are less lipophilic the penetration of compounds in the very bacteria is smaller.