Investigation of Antibacterial Activity of Two Kinds of Novel Schiff Bases on Escherichia coli by Microcalorimetry

Abstract

The microcalorimetric method was used to study the antibacterial activity of two newly synthesized Schiff base compounds (H 2 L 3' and H 2 L 3 ) on Escherichia coli, trying to obtain the action on both of multiplying bacteria and non-multiplying bacteria at one experiment. The metabolic power-time curves of the bacteria treated with the compounds were obtained, and the thermokinetic parameters were analyzed, from which the antibacterial activities of these compounds were evaluated. The results showed that both of the two compounds have good activity on aerobic multiplying metabolism of E. coli, with the value of IC 50 75.8 and 168.8 mg/L respectively, but have not effective action on 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 value of MSC 50 (minimum stationary-cidal concentration 50) of them is 118 and 187.5 mg/L, respectively. So, H 2 L 3' has stronger antibacterial action on E. coli than H 2 L 3 either for multiplying bacteria or non-multiplying bacteria, and their activity on the aerobic multiplying bacteria of E. coli is mainly shown. It does strongly suggest that the calorimetric method should play an important role in the fight against the drug-resistant bacteria.

Preliminary screening for extraction techniques and bioactive fraction of Coptidis Rhizoma based on microcalorimetry

“…The growth process of E. coli affected by different fractions was monitored continuously by this microcalorimeter and the thermogenic power-time curve was determined. All the experiments were carried out under aseptic condition (Zhu et al, 2006;Kong et al, 2009b).…”

Study of the Influence of Different Diphenol Compounds on Soil Microbial Activity by Microcalorimetry

“…12 The total thermal effect (Q total ), which relates to the degradation of the carbon source and reflects the amount of the carbon source used, was calculated by integrating each power-time curve from the beginning to the end. 4,6,19 Results and discussion…”

“…In addition, slow reactions can be easily followed by a continuous recording of the signal for a long time without any disturbance of the system. 5,6 In this procedure a complete determination of a given microbial activity can be outlined, which reflects the thermal effect that is largely derived from the catabolic breakdown of sub-strate and also the anabolic reaction that has another contribution to the overall balance of the system. 7 The aim of this study is to take a further step towards quantitative application of microcalorimetric method to the evaluation of the environmental impact of chemical substances on soil microbial activities.…”

Fluorescence Quenching Study on the Interaction of Some Schiff Base Complexes with Bovine Serum Albumin

“…1,5 A large number of Schiff bases and their complexes have been studied because of their interesting and important properties, e.g., their ability to reversibly bind oxygen, catalytic activity toward hydrogenation of olefins and transfer of an amino group, photochromic properties, complexing ability towards certain toxic metals, 6 chemotherapeutic properties and unusual physiochemical properties. 7 Since the first Schiff base metal complex was synthesized by Schiff in 1869, a great amount of research has been preformed in this field to investigate their synthesis, structure, characteristics, bioactivity and biosimulations, etc.. [8][9][10][11][12][13][14][15] Some Schiff bases are known to slow the growth of several animal tumors and some metal chelates have shown good antitumor activities against animal tumors. 16 In this context, the interaction of new synthetical Schiff base and its metal complexes with bovine serum albumin was studied by fluorescence spectroscopy under physiological conditions.…”