Effects of extract and essential oil of Rosmarinus officinalis L. on TNBS-induced colitis in rats

Rosmarinus officinalis L. (Family Lamiaceae) popularly named rosemary, is a common household plant grown around the world, including Iran. Rosemary aerial parts are used as flavoring agent in foods, beverages, and cosmetic preparations and have various traditional uses in ethnomedicine including: analgesic, anti-inflammatory, anti-rheumatic, spasmolytic, carminative and choleretic applications. This study was carried out to investigate the effects of rosemary leaves hydroalcoholic extract (RHE) and essential oil (REO) in a well-defined model of experimental colitis induced by trinitrobenzene sulfonic acid (TNBS) in rats. Different doses of RHE (100, 200 and 400 mg/kg) and REO (100, 200 and 400 μl/kg) were administered orally and intraperitoneally (100, 400 mg/kg and 100, 400 μl/kg) to male Wistar rats (n=6), 6 h after colitis induction and continued for 5 days by intracolonic instillation of 0.25 ml TNBS (80 mg/kg)/ethanol 50% v/v. Wet colon weight/length ratio was measured and tissue damage scores as well as indices of colitis were evaluated both macroscopically and histopathologically. RHE and REO at all test doses used were effective to reduce colon tissue lesions and colitis indices while greater doses were significantly effective to diminish histopathologic parameters irrespective to the route of administration. Administration of oral prednisolone, Asacol(®) (mesalazine microgranules) and parenteral hydrocortisone acetate were effective to reduce colon tissue injures as well. These data suggest that RHE and REO are both effective to possess anti-colitic activity, and reinforce the use of this plant as a remedy for inflammatory bowel diseases in traditional medicine.