Preparation, characterization and antimicrobial activities of cyclic substituted chitosan derivatives

Six cyclic substituted chitosan derivatives were synthesized, and their structures were characterized by FTIR , 13 C 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 Verticillium 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.