Antibacterial effect and toxicity of synthesized salicylanilide derivatives

5 nitro- and chloro-salicylanilide derivatives were synthesized by a simple condensation reaction between phenylsalicylate and the required nitroaniline derivative. The compounds were subjected to direct chlorination in CCl4 without any catalyst and were identified by microanalysis, m. p. and spectral studies. The antibacterial activity was investigated against Escherichia coli, Bacillus subtilis, Pseudomonas aeruginosa, and Staphylococcus aureus. The prepared derivatives were evaluated for their acute toxicity on Swiss albino mice. The compounds 5,2'-dichloro-4'-nitrosalicylanilide and salicyl-3'-nitroanilide were the most active against the test organisms, but they showed fluctuating toxicity effect at the dose of 500 mg/kg. The structure-activity relationship and the toxicity tests verified the compound salicyl-4'-nitroanilide as a reasonable antibacterial agent against the four test organisms without any sign of toxicity symptoms up to the dose of 1000 mg/kg.