Synthesis, Characterization And Antibacterial Activity Of P-(Methyl-sulfonyl)Benzaldehyde Derivative

Thiamphenine is a broad-spectrum antibiotic as chloromycetin. A variety of bacteria have drug resistance on it owing to overusing and it has side effect on patient. It is pressed for developing novel and fewer side effect antibacteria agents. Shiff bases and cinnamic acids as well as coordination compounds of cinnamic acid seem to be suitable candidate for low toxic side effects and efficient antibacteria agents in accord with the previous study. In the dissertation, we attempt to obtain the low toxic and efficient leading drugs via synthesizing Shiff bases, cinnamic acids and coordination compounds of cinnamate using p-(Methyl-sulfonyl)benzaldehyde as initial compound.Firstly, we have synthesized these Schiff bases, cinnamic acids and metal coordinations as follows:(1) These Schiff bases were synthesized by condensing the p-(Methyl-sulfonyl)benzaldehyde with organic amines.(2) The cinnamic acid was synthesized by reacting the p-(Methyl-sulfonyl)benzaldehyde with the malonic acid.(3) The coordinations were obtained by chelating the cinnamic acid, organic amines and metal ions. And then these compounds were characterized by infrared spectroscopy and nuclear magnetic resonance spectrometer, and their structures were determined by single crystal X-ray diffraction analysis.Secondly, the antimicrobial activities above mentioned Schiff bases were evaluated against E. Coli, P. Putida, B. Subtilis and B. Cereus. Among these Schiff bases tested, compounds10,11,20displayed inhibitory activity with IC50values of2.5-20μg/mL against the four bacteria. Especially, the compound20showed the highest inhibitory potency (IC50=1.25μg/mL) against P. Putida. In addition, seven Schiff bases among Schiff bases tested displayed strongly inhibitory activity (IC50<5μg/mL) on P. Putida. All of these Schiff bases exhibited higher inhibitory potency against Gram-negative bacterium than against Gram-positive bacterium. And structure-activity relationships were also discussed based on the obtained experimental data. These Schiff bases formed by the aromatic amine with electron-withdrawing group and p-(Methyl-sulfonyl)benzaldehyde displayed well antibacteria activity than those Schiff bases prepared by the aromatic amine with electrondonating group and p-(Methyl-sulfonyl)benzaldehyde. While these Schiff bases, synthesized by condensing diamine with p-(Methyl-sulfonyl)benzaldehyde, exhibited higher inhibitory activity than those formed by monoamine and p-(Methyl-sulfonyl)benzaldehyde.Thirdly, p-(Methyl-sulfonyl)cinnamate and its coordinations were evaluated against the bacteria tested. The p-(Methyl-sulfonyl)cinnamate displayed good inhibitory activity (IC50<20μg/mL) against the four bacteria. The coordination formed by the cinnamate, metal ions and diamines showed higer inhibitory activity than the cinnamic acid against the bacteria tested. The cadmium complex of the cinnamate displayed strong inhibitory activity with IC50values of5μg/mL against P. Putida, meanwhile the nickel coordination also exhibited good inhibitory potency with IC50values of5μ/mL against B. Subtilis.