Protective effect of curcumin, a Curcuma longa constituent, in early colonic inflammation in rats

Abstract Curcumin, a polyphenol derived from the plant, Curcuma longa , has a variety of pharmacological effects, including chemotherapeutic, anti‐inflammatory, antiangiogenic, and antioxidant activities. To gain a better understanding of the effects and mechanisms of action of curcumin on the acute injury caused by intra‐colonic administration of acetic acid (AA) in rats, inflammation was assessed by histology and myeloperoxidase activity (MPO; an index of neutrophil infiltration in the mucosa); Th1 and Th2 cytokine production; histological and histochemical analysis of the lesions; nitrite production in colon mucosa; and the expression of iNOS, COX‐1 and ‐2 using Western blotting and inmmunohistochemistry. We also studied the involvement of the p38 MAPK/JNK signalling pathway in the protective effect of curcumin in acute colonic inflammation. Curcumin (50–100 mg/kg/day) reduced the degree of colonic injury, the index of neutrophil infiltration and Th1 cytokine secretion, and increased IL‐10 production, reduced colonic levels of nitrites, and reduced COX‐2 and iNOS overexpression. A reduction in the activation of p38 and JNK MAPKs was also observed. Thus, we show that the widely used food additive, curcumin reduced the development of AA‐induced colitis and alleviated the inflammatory response. Inhibition of MAPK signalling by curcumin could explain the changes on the cytokine Th1/Th2 profile, the reduction of COX‐2 and iNOS signaling, as well as the decreased nitrite production in colonic mucosa, suggesting that curcumin may be useful in the treatment of ulcerative colitis. Drug Dev Res, 2009. © 2009 Wiley‐Liss, Inc.