Anti-Inflammatory Effect of Cudrania tricuspidata Extract and Stewartia koreana Extract Mixture in a Collagen-Induced Arthritis Mouse Model

Abstract

Cudrania tricuspidata extracts (CTE) and Stewartia koreana extracts (SKE) are viable drugs for managing inflammation. We investigated the nitric oxide levels of CTE and a mixture of CTE/SKE (CTE mix) against lipopolysaccharide-induced RAW264.7 cells. In addition, we administered the CTE and CTE mix to mice with collagen-induced arthritis to confirm an anti-inflammatory effect against rheumatoid arthritis. We analyzed arthritis symptoms by oral administration of CTE mix using a CIA-induced animal model and analyzed the inhibitory activity of NO production with in vitro experiments. Both the CTE and CTE mix decreased nitric oxide levels, and a 2:1 ratio of CTE mix was most effective in vivo among the varying ratios of CTE mix tested. The spleen size increased by about 2.1 times, and the lymph node size decreased by about 2.5 times relative compared to the vehicle group. In blood biochemical analyses, tumor necrosis factor–α levels decreased by about three times, interleukin-1β and interleukin-6 levels were reduced by about eight times and three times, and PRG4 expression levels were increased by about 2.5 times relative to the vehicle group. We suggest that the CTE mix was superior to CTE alone and has potential as an anti-inflammatory treatment for patients with rheumatoid arthritis.