High antibacterial activity and low toxicity of pyridoxal derivatives of chitosan and their nanoparticles

The pyridoxal derivatives of chitosan with various degrees of substitution (DS) were synthesized from low-, moderate- and high-molecular-weight chitosans by their reaction with pyridoxal followed by treatment with NaBH₄. The derivative of moderate molecular weight and high DS demonstrated a maximum antibacterial activity against S. aureus and E. coli. The nanoparticles of this derivative obtained by ionic gelation are nontoxic, and they exhibit a high in vitro antibacterial effect, which slightly exceeds that of ampicillin and gentamicin.