Physiological activities of chitosan and N‐trimethyl chitosan chloride in U937 and 3T3‐L1 cells

Chitosan (CH) is a biopolymer with biocompatible, biodegradable, and bioactive properties. N,N,N‐trimethyl chitosan chloride (TMC) is a quaternized form of CH that is highly cationic and more water soluble than unmodified CH. The physiological activities of CHs with different molecular weights (M_w) and degrees of TMCs quaternization were investigated in U937 and 3T3‐L1 cell lines. ¹H‐NMR spectrometry and size exclusion chromatography were used for characterization of the biopolymers. The half inhibition concentration (IC₅₀) of DPPH‐radical‐scavenging activity was below 0.9 mg/m with quaternized CHs. The IC₅₀ values of chitooligosaccharides, low‐ and medium‐molecular‐weight CHs were 8.4, 10.9, and 13.9 mg/ml, respectively. High‐molecular‐weight CHs and TMCs showed apoptotic activity on U937 cells. T41, a TMC of 549 kDa with a 41% degree of quaternization (DQ), yielded 30.7% apoptotic cell death in U937 at 20 µg/ml and effectively repressed cell differentiation and triglyceride accumulation in 3T3‐L1. Depolymerized CHs reduced triglyceride accumulation but also caused cell differentiation. TMCs showed repressor activity to both cell differentiation and triglyceride accumulation. Increasing the molecular weight of CHs and TMCs generally resulted in increased physiological activity. Copyright © 2010 John Wiley & Sons, Ltd.