Cytotoxicity on Cancer Cells according to Average Molecular Weight of Chitosan Hydrolysates

Abstract

To confirm the molecular characteristics of chitooligosaccharides (COS) derived from the hydrolysis of high molecular weight chitosan (HMWC), measuring average molecular weight (MW) using gel permeation chromatography (GPC) and their cytotoxicity was confirmed by treatment with several cancer cells. To evaluate the cytotoxicity of Chi-S according to different MW on various cancer cells, two types of chitooligosaccharide (COS) named Chi-S and COS-S were subjected in a concentration-dependent manner. It was divided into chitinous active substance (Chi-S) containing N-acetylglucosamine and chitosan oligosaccharide substance (COS-S), respectively. The average MW of Chi-S obtained by enzymatic treatment of HMWC for 24 h was confirmed to be about 2.7 kDa. Chi-S showed no cytotoxicity against all treated cancer cells. However, rather than showing cytotoxicity in immune macrophages RAW264.7, significant cell proliferation was observed. On the other hand, COS-S (average MW of approximately 7.3-kDa) obtained by enzymatic treatment of HMWC for 12 h showed significant cytotoxicity against all cancer cells including immune macrophages RAW264.7 at a high concentration range of 100 mg/mL or more. Furthermore, no significant changes were observed in breast cancer cells and normal cells treated with the control group. Therefore, based on the results, we estimate that Chi-S may be involved in indirect anticancer activity by selective or adaptive immunological activity according to the molecular characteristics. Our data will be a good guide for subsequent studies that can focus on the particular activity of molecules according to the difference between chitosan MW and the deacetylation degree (DD) of HMWC.