Purpose: The present study was carried out to modify chitosan with monomethyl fumaric acid to enhance its solubility, antibacterial and antioxidant activities.
Methods: Conjugation of chitosan with MFA in acidic medium was achieved by using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) as mediator. Three different kinds of conjugate samples 1, 2 and 3 were synthesized by feeding different concentration of MFA. The resulting materials were characterized by 1H NMR, 13C NMR, High-resolution XRD, and TNBS assay. Solubility, antibacterial and antioxidant activities of the conjugates samples have been studied by solubility test, 96 well-plate assay, and 1, 1-diphenyl-2-picrylhydrazyl (DPPH) assay, respectively.
Results: The 1H NMR, 13C NMR, HRXRD confirmed the successful synthesis of conjugates samples 1, 2 and 3. The degree of substitution (DS) for each samples ranging from 1.82±0.05% to 7.88±0.04%. Conjugates sample 1, 2 and 3 are readily soluble in water and swelled by dimethyl sulfoxide (DMSO), toluene and dimethylformamide (DMF). The antioxidant activity for all the conjugate samples have been significantly improved (P<0.05) compared to the native chitosan. Upon antibacterial activity at pH 4.0, all the conjugate samples showed significant (P<0.05) antibacterial activity against gram-positive Staphylococcus aureus strains, Listeria monocytogenes strains and gram-negative Escherichia coli strains and Salmonella Enteritidis strains compared to native chitosan.
Significance: MFA-modified chitosan has shown enhanced antioxidant and antibacterial activities along with solubility, and could be used as a novel food preservative and packaging material for long time food safety and security.