Novel non-toxic high efficient antibacterial azido chitosan derivatives with potential application in food coatings.

In this work, we developed a simple method for the preparation of N-(3-azido-2-hydroxypropyl)chitosan. We compared the antibacterial activity of N-(3-azido-2-hydroxypropyl)chitosans and previously synthesized N-(2-azidoethyl)chitosans. N-(3-azido-2-hydroxypropyl)chitosans possess higher antibacterial effect which is comparable with that of ampicillin and gentamicin. The effect is due to azido pharmacophore -CH2-CH(OH)-CH2-N3 (for N-(3-azido-2-hydroxypropyl)chitosan) or -CH2-CH2-N3 (for N-(2-azidoethyl)chitosan) introduced in chitosan chain, since the corresponding organic azides NH2-CH2-CH2-N3 and NH2-CH2-CH2-N3 are characterized by high antibacterial activity. However, high antibacterial organic azides NH2-CH2-CH2-N3 and NH2-CH2-CH2-N3 are characterized by high toxicity. Their conjugation to the chitosan chain saves their antibacterial effect, but strongly diminishes their toxicity, and the toxicity of the resulting derivatives is comparable with that of the starting chitosan. These findings are of interest to food science, since novel effective food coatings can be developed on basis of prepared derivatives.