Preparation, characterization and antimicrobial activities of cyclic substituted chitosan derivatives

Six cyclic substituted chitosan derivatives were synthesized, and their structures were characterized by FTIR, C-13 NMR and elemental analyses. Additionally, their antimicrobial properties were studied. The synthesized derivatives showed significantly greater zones of inhibition compared with chitosan. The zone of inhibition values produced by C-2-2-naphthylamine formamide-C-6-2-naphthylamine formyl ester-polymer chitosan against Sarcina sp., Staphylococcus aureus and Escherichia coli were 24 mm, 21 mm and 21 mm, respectively, whereas those of C-2-cyclohexylamine formamide-C-6-cyclohexylamine formyl ester-low chitosan against Fusarium equiseti and Verti-cillium dahliae were 14 mm and 15 mm, respectively. The antibacterial abilities of chitosan and its derivatives against the Gram-positive bacteria Sarcina sp. and Staphylococcus aureus were stronger than those against the Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa. In addition, all of the high and low molecular weight chitosan derivatives showed greater bacteriostatic activities than antifungal activities. The results provided a useful reference for the development of chitosan and its derivatives used as new pesticides.

Automated summary

Six cyclic substituted chitosan derivatives were synthesized and characterized by various methods, showing greater antibacterial efficacy against Gram-positive bacteria compared to chitosan. The results suggest that these derivatives have potential as new pesticides.