微量热研究几种新型吡啶酰胺希夫碱对大肠杆菌的抑制作用

用微量热研究一系列新型吡啶酰胺希夫碱对大肠杆菌的抑制作用, 不同的吡啶酰胺希夫碱衍生物对大肠杆菌生长的抑制作用不同. 通过热动力学模型计算得到生长速率常数(k)和抑制率(I), 我们获得了吡啶酰胺希夫碱衍生物的抗菌作用效果. 通过药物作用于细菌处于生长对数期的实验发现, 有两种化合物(F和G)对大肠杆菌生长有非常好的抑制作用, 他们的半抑制浓度(IC50)分别是0. 106 和0. 113 g/L, 但是药物对大肠杆菌的无氧发酵过程抑制作用比较差. 通过进一步分析药物结构与药物半抑制浓度, 我们发现: 希夫碱衍生物的亲水性对其抗菌活性有很大的影响, 这主要是由细菌的细胞膜结构不同所致. 对希夫碱及其碱衍物的结构与抗菌活性关系进行了初步探讨, 它们对大肠杆菌的抗菌活性顺序为: F＞G＞C＞D＞E＞B＞A.

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

The 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 .