Inhibitory effects of an aqueous extract of Cornus kousa Burg. leaves on TNF-alpha-induced chemokine expression and monocyte adhesion to human colonic epithelial cells

Abstract

An aqueous extract of Cornus kousa Burg. leaves (ACK) that contained high amount of polyphenols showed significant antioxidant activity against diphenylpicrylhydrazyl (DPPH) radicals and TNF-alpha-generated reactive oxygen species. ACK at concentrations of 10 and 50 microg/mL significantly inhibited TNF-alpha-induced adhesion of U937 pre-monocytic cells to HT-29 colon epithelial cells in a concentration-dependent manner. The reduced adhesion by ACK correlated with the suppressed expressions of monocyte chemoattractant protein (MCP)-1 and interleukin (IL)-8, the major inflammatory bowel disease (IBD)-associated chemokines. Moreover, ACK significantly suppressed TNF-alpha-induced translocation of redox-sensitive nuclear factor (NF)-kappaB as well as degradation of cytosolic I-kappaBalpha. The effective concentrations of ACK were much lower than that of 5-aminosalicylic acid (3.06 mg/mL), which is an active metabolite of sulfasalazine, a well-known drug used in the treatment of IBD. The results indicate that ACK may provide a potential benefit for the prevention and treatment of inflammatory diseases such as IBD.