Microcalorimetric Study on the Inhibition of Escherichia coli by Some Novel Pyridine Amide Schiff Base Derivatives

Abstract

AbstractThe antibacterial effect of a series of novel pyridine amide Schiff base compounds on Escherichia coli was investigated by a microcalorimetric method at 37 °C. The metabolic power‐time curves of the bacteria treated by the compounds were obtained, and the thermokinetic parameters were analyzed, from which the antibacterial activities of these compounds were evaluated. The results show that two compounds F and G have good activity on aerobic multiplying metabolism of E. coli, with the value of IC50 106 and 113 mg/L respectively, but have no effective action on the fermentation metabolism of E. coli. The action of the compounds on the non‐multiplying metabolism was investigated by taking the heat output of E. coli in the stationary phase as the guideline of the activity. The experimental results revealed that the hydrophilicity of these Schiff bases had a great influence on their antibacterial activity, which results from the bacterial cell wall structure. The antibacterial structure‐activity relationship of these Schiff base derivatives was also briefly discussed. The antibacterial activity of the compounds against E. coli was as follows: compound F>G>C>D>E>B>A.