Structural characterization and antitumor effects of chitosan oligosaccharides against orthotopic liver tumor via NF-κB signaling pathway

•This paper focused on the structural features of COS, while other papers paid little attention.•This paper studied COS from the perspectives of immunoregulation and direct impact on tumor cells.•Antitumor effect of COS was studied on orthotopic liver tumor, imitating primary hepatic cancer.