Study on antimicrobial activity of C3，6-diacetylated phenyl-thiosemicarbazone-chitosan derivatives

By testing the antimicrobial activity of 10 kinds of C3，6-dichloroacetyl phenyl- thiosemicarbazonechitosan derivatives on four kinds of animal pathogenic bacteria and four kinds of plant pathogenic fungi，several compounds with better activity were selected as prodrug. By using Stepwise Dilution Method，the OD value of the derivatives in 12 concentrations was determined by the Microplate Reader，and the minimum inhibitory concentration （MIC） and the minimum bactericidal concentration（ MBC） were determined according to the inhibitory rate of bacteria. A Mycelium Growth Rate Method was used to determine the inhibitory rate of derivatives on plant pathogenic fungi at five concentrations. The results showed that the antimicrobial effects of 10 kinds of derivatives on all tested strains were better than that of raw chitosan. The antibacterial effect of gram negative bacteria was better than that of Gram-positive bacteria. The minimum inhibitory concentration（ MIC） and minimum bactericidal concentration （MBC） of the derivatives against Escherichia coli were 14.80 μg/mL and 29.16 μg/mL respectively. All of the derivatives had a definite antifungal effect on fungi in the concentration range of 0.05 mg/mL-2 mg/mL，with a maximum inhibition index of 100%. The antifungal activity of F. oxysporum f. sp. cucumerinum was lower than that of other three kinds of plant pathogenic fungi. 3，6-DAPTSCZHCS，3，6-DA（p-T）TSCZHCS，3，6-DA（p-NP） TSCZHCS，3，6-DA（o-CP）TSCZLCS，3，6-DA（p-NP）TSCZLCS had strong antimicrobial activity to all test strains，and had the value for further research and development.