Synthesis, Characterization, and the Antifungal Property of Aminoethyl Chitosan Quaternary Ammonium Salts

Chemical modification of chitosan is one of effective methods to improve the biological activity of chitosan. In this paper, aminoethyl chitosan quaternary ammonium salts, including N ‐trimetyl quaternary ammonium salt chitosan (TMC), 6‐O‐(aminoethyl)‐2‐trimethyl quaternary ammonium chitosan derivative (ONC), and 6‐ N ‐(aminoethyl)‐2‐trimethyl quaternary ammonium chitosan derivative (NNC), are successfully designed, synthesized, and characterized by FT‐IR, 1 H NMR, and elemental analyses. Moreover, three kinds of antifungal activities, including B. cinerea Pers ., Gibberella zea , and P. asparagi , are all tested by hyphal measurement in vitro. The results show that all chitosan derivatives have better antifungal activities than chitosan. And the antifungal activity decrease in the order: NNC>ONC >TMC>chitosan at 1.0 mg mL −1 . Furthermore, the inhibitory indices of NNC and ONC against three kinds of phytopathogens are higher than 75% at 1.0 mg mL −1 . Especially, the inhibitory index of NNC against B. cinerea Pers . attain even 90% at 1.0 mg mL −1 . These data demonstrate that the aminated chitoan derivative could remarkably improve the antifungal activity of chitosan. On the one hand, the higher positive charge would interact with the anionic components to damage the cell wall. On the other hand, based on the “permeability” point, the aminoethyl as lipophilic group might pass the oil film into the cell.