Facile and convenient electrochemical syntheses of novel multifunctional (catalytic, antioxidant and in vivo antimicrobial) phosphorylated chitosan derivatives

The electrochemical coupling of N-protected chitosan with diphenylphosphine oxide was recognized as new facile, fast, and convenient route to phosphorylated chitosans. The reaction affords low substituted (capable of self-assembling into nanoparticles), moderately substituted (water soluble) or highly substituted (soluble in both water and toluene) polymeric chitosan phosphonates. The degree of substitution can be adjusted by simply increasing the triphenylphosphine oxide/chitosan ratio. Highly substituted polymers (CH-P0.70) are efficient homogeneous catalysts towards the model reaction of monoglyceride synthesis (ca. 100% yield in 3 h). The phosphorylated chitosans are also efficient antioxidants. Their antioxidant effect increases with an increase in their degree of substitution. CH-P0.70 exhibits an antioxidant activity comparable to that of the natural antioxidant ascorbic acid. Remarkably, the highly substituted species is characterized by a strong in vivo antibacterial effect which is even more pronounced than that of the commercial antibiotics ampicillin and gentamicin. Moreover, the obtained phosphorylated chitosan CH-P0.70 demonstrates neither acute nor subacute in vivo toxicity. © 2024 Elsevier Ltd