Sulfated modification of hyaluronan tetrasaccharide enhances its antitumor activity on human lung adenocarcinoma A549 cells in vitro and in vivo

•Chondroitinase ABC enzyme was induced from recombinant engineering bacterial E. coli BL21/pET-28a-csabc.•Hyaluronan tetrasaccharide (HA4) and its sulfated derivates with different sulfate contents were prepared and identified.•HA4 and its three sulfated derivatives showed different antitumor activities.•HA4S2 exhibited the best antitumor activity by inducing apoptosis expression.