Studies on anti-hepatocarcinoma effect, pharmacokinetics and tissue distribution of carboxymethyl chitosan based norcantharidin conjugates

•Carboxymethyl chitosan (CMCS) covalently conjugated with norcantharidin (NCTD).•CNC possessed enhanced antitumor activity and reduced systemic toxicity.•CNC exhibited different pharmacokinetics and tissue distribution with NCTD.•CNC could serve as a potential therapeutic candidate for NCTD in tumor therapy. Aiming to enhance therapeutic efficiency and reduce toxic effect of norcantharidin (NCTD), NCTD-conjugated carboxymethyl chitosan (CMCS) conjugates (CNC) were prepared and evaluated for the treatment of hepatocellular carcinoma. In vitro cellular assays revealed that CNC conjugates possessed potent inhibitory effects on the proliferation and migration of BEL-7402 cells. Besides, CNC could change nuclear morphology of tumor cells. In comparison with free NCTD at equivalent dose, CNC exerted enhanced therapeutic efficiency and diminished systemic toxicity in H22 tumor-bearing mice with a tumor inhibition rate of 56.20%. Further investigation about pharmacokinetics and tissue distribution by high performance liquid chromatography (HPLC) analysis indicated that CNC showed a longer retention time in blood circulation and reduced distribution in heart and kidney tissues, thereby exerting different antitumor efficacy and toxicity compared with free NCTD. Our results suggested that CNC conjugates based on CMCS as polymer carriers might be used as a potential clinical alternative for NCTD in tumor therapy.