The possible mechanisms of Picrasma quassiodes (D. Don) Benn. in the treatment of colitis induced by 2,4,6-trinitrobenzene sulfonic acid in mice.

ETHNOPHARMACOLOGICAL RELEVANCE: Picrasma quassiodes (D. Don) Benn.(PQB) is used in folk medicines for the treatment of colds, upper respiratory infection, acute tonsillitis, acute gastroenteritis, bacillary dysentery and a variety of acute infectious diseases in Asia. Although recent reports indicate that PQB has antibacterial, and anti-inflammatory effects, its effects on colitis and its inhibitory mechanisms have not been previously reported.

AIM OF THE STUDY: To assess the effects and the mode of action of the extract of Picrasma quassiodes (D. Don) Benn.(PQB) on a model of colitis in mice induced by trinitrobenzene sulfonic acid (TNBS).

MATERIALS AND METHODS: We induced mice colitis using TNBS/ethanol, then different doses of Picrasma quassiodes (D. Don) Benn.(PQB) extract (100, 200 and 400 mg/kg/day) and sulfasalazine (500 mg/kg/day) were administered by gavage for 7 days after the induction of colitis. The mice body weight, colonic wet weight, colonic lengths, myeloperoxidase (MPO) activity, macroscopic and histological colon injury were observed. Pro-inflammatory cytokines such as: tumor necrosis factor-alpha (TNF-α) and interleukin-8 (IL-8) were assayed by enzyme-linked immunoassay. The protein expression of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) in the colons were determined by immunohistochemical analysis.

RESULTS: PQB administration effectively prevented mice diarrhea, decreasing of the body weights, shortening of colon length and increasing of colon wet weight. Macroscopic and histological examinations also indicated that it was protected against colonic edema, ulceration and MPO activity elevation. Furthermore, PQB inhibited the abnormal secretions of pro-inflammatory cytokines, such as TNF-α and IL-8. Additionally, administration of PQB effectively inhibited COX-2 and iNOS protein expression.

CONCLUSIONS: These results suggest that PQB has an anti-inflammatory effect on TNBS-induced colitis due to the down-regulations of the productions and expressions of inflammatory mediators, and that it may be a potential inflammatory bowel disease (IBD) drug candidate.