As a promising biological material, chitooligosaccharide (COS) has attracted increasing attention because of its unique biological activities. In this study, fourteen novel phenolic acid functional COS derivatives were successfully prepared using two facile methods. The structures of derivatives were characterized by FT-IR and 1H NMR spectra. The in vitro antioxidant activity experiment results demonstrated that the derivatives presented stronger 1,1-Diphenyl-2-picryl-hydrazyl (DPPH), superoxide, hydroxyl radical scavenging activity and reducing power, especially the N,N,N-trimethylated chitooligosaccharide gallic acid salt (GLTMC), gallic acid esterified N,N,N-trimethylated chitooligosaccharide (GL-TMC) and caffeic acid N,N,N-trimethylated chitooligosaccharide (CFTMC) derivatives. Furthermore, the antifungal assay was carried out and the results indicated that the salicylic acid esterified N,N,N-trimethylated chitooligosaccharide (SY-TMC) had much better inhibitory activity against Botrytis cinerea and Fusarium graminearum. Additionally, the results of the bacteriostasis experiment showed that the caffeic acid esterified N,N,N-trimethylated chitooligosaccharide (CF-TMC) had the potential ability to inhibit Escherichia coli and Staphylococcus aureus bacteria. Altogether, this study may provide a neoteric method to produce COS derivatives with significantly increased biological activities, which have potential use in food, medicine, and health care products and other related industries.
Keywords: antibacterial activity; antifungal activity; antioxidant activity; chitooligosaccharide; chitooligosaccharide quaternary ammonium salt derivatives; phenolic acid.