Study On Antimicrobial Activities Of Novel Acyl-thiosemicarbazone Derivatives Of Chitosan

With the abuse of chemical pesticides and antibiotics becoming more and more serious,environmental pollution and human health are greatly threatened.At the same time,the drug resistance of bacteria is increasing,which has a bad effect on the development of agriculture and animal husbandry.Therefore,the development of environment-friendly pesticides and veterinary drugs has become a hot topic in recent years.Our group had synthesized 60 kinds of novel acyl-thiosemicarbazone derivatives of Chitosan,and hoping to improve the solubility of Chitosan and reduce the toxicity of thiourea by combining thiourea and Chitosan.In this paper,the antimicrobial activities of the 60 derivatives was tested in vitro,the MIC and MBC values of 4 species of pathogenic bacteria（Escherichia coli,Staphylococcus aureus,Pseudomonas aeruginosa and Microccus luteus）and the inhibitory rate of 4 kinds of plant pathogenic fungi（Alternaria solani,F.oxysporum f.sp.cucumerinum,C.gloeosporioides（Penz.）Saec and F.oxysporum f.sp.vasinfectum）were tested.And compared with the antimicrobial effect of the raw materials Chitosan,ammonium thiourea crystal and Norfloxacin and other positive control drugs.The results showed that the antimicrobial activities of most of the derivatives was better than that of Chitosan.3,6-DBZ（o-T）TSCZHCS、3,6-DBZ（p-T）TSCZHCS、3,6-DBZ（o-CP）TSCZHCS、3,6-DBZ（o-CP）TSCZLCS、3,6-DA（o-T）TSCZHCS、3,6-DA（o-CP）TSCZHCS、3,6-DA（o-CP）TSCZLCS、3,6-DA（p-NP）TSCZLCS、3,6-DCA（o-T）TSCZHCS、3,6-DCA（o-CP）TSCZHCS、3,6-DCA（o-T）TSCZLCS 11 derivatives showed good antibacterial activities to four kinds of animal pathogenic bacteria.The MIC and MBC of 3,6-DBZ（o-CP）TSCZHCS against Escherichia coli were 7.40μg·mL^-1 and14.80μg·mL^-1 respectively,and the antibacterial activity is similar to that of Norfloxacin.All of the derivatives had a definite antifungal effect on fungi in the concentration range of 0.05–2 mg·mL^-1.3,6-DBZ（o-T）TSCZHCS、3,6-DBZ（p-T）TSCZHCS、3,6-DAPTSCZHCS、3,6-DA（p-NP）TSCZHCS and 3,6-DCA（o-T）TSCZHCS 5derivatives showed good antifungal activities toward four kinds of plant pathogenic fungi.The inhibition index of 3,6-DBZ（o-T）TSCZHCS and 3,6-DBZ（p-T）TSCZHCS at the concentration of 2 mg·mL^-11 to F.oxysporum f.sp.vasinfectum was 100%.At the same time,the cytotoxicities of thirty kinds of Chitosan derivatives（which were not protected two amino groups on chitosan）were tested in this paper.The results showed that the cytotoxicity of DBZ（o-CP）TSCZHCS、DBZ（p-NP）TSCZHCS、DCA（o-CP）TSCZHCS were lower than that of the corresponding amino thiourea crystals.This study provides the experimental basis for the development of new antimicrobial drugs,and lays a foundation for the preparation of new antimicrobial agricultural fungicides for the next step.