Chitosan-hydroxycinnamic acid conjugates: Optimization of the synthesis and investigation of the structure activity relationship

Vivien Nagy, Priyanka Sahariah, Martha Ásdís Hjálmarsdóttir, Már Másson*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


A new synthesis method was developed and optimized by a full factorial design for conjugating hydroxycinnamic acids (HCA-s) to chitosan. Cinnamic acid and tert-butyldimethylsilyl protected HCA-s were converted to their corresponding acyl chlorides and reacted with 3,6-di-O-tert-butyldimethylsilyl-chitosan to selectively form amide linkages, resulting in water-soluble conjugates after deprotection. Nineteen conjugates were obtained with various degrees of substitution (DS) ranging from 3% to 60%. The conjugates were found to be bactericidal against Staphylococcus aureus and Escherichia coli, with their activities equal to chitosan at low DS but an increase in the DS correlated with reduced activity. DPPH (2,2-diphenyl-1-picrylhydrazyl) scavenging assay was performed to determine the EC50 values. Chitosan only exhibited low antioxidant activity, whereas the HCA-chitosan conjugates exhibited higher antioxidant activities correlating with the DS. One caffeic acid conjugate (21%) was 4000 times more active than chitosan and more active than free caffeic acid.

Original languageEnglish
Article number118896
JournalCarbohydrate Polymers
Publication statusPublished - 1 Feb 2022

Bibliographical note

© 2021 Elsevier Ltd. All rights reserved
The research work was funded by the Icelandic Research Fund
(Rannis Grant No. 185188-053) and by a doctoral grant from the Uni-
versity of Iceland research fund. We thank Primex ehf for donating the
chitosan starting material.

Other keywords

  • Antibacterial
  • Antioxidant
  • Chemical modification
  • Chitosan
  • Design of Experiment (DOE)
  • Protection groups


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