Anti-inflammatory Effect of Myrtus communis Hydroalcoholic Extract and Essential Oil on Acetic Acid–induced Colitis in Rats

Background: Colitis is an inflammatory bowel disease, many causes are involved in its pathogenesis and development. Myrtus communis (M. communis) contains anti-inflammatory and antioxidant ingredients that are useful for the treatment of inflammatory disease. 
Objectives: The purpose of this study was to investigate the effect of M. communis hydroalcoholic extract (MCHE) and essential oil (MCEO) on acetic acid–induced colitis model. 
Materials and Methods: MCHE (50, 100, 200, and 400 mg/kg) and MCEO (62.5, 125, 250, and 500 μL/kg) were given orally to rats, 2 h before induction of colitis and continued for further 4 days. Prednisolone (4 mg/kg) and mesalazine (100 mg/kg) were used as reference drugs. After 5 days, colitis markers and indices were investigated on isolated colons. Biochemical evaluation of inflamed colon was performed using assay of myeloperoxidase (MPO) activity. 
Results: Acetic acid caused significant inflammatory reactions as indicated by macroscopic and microscopic changes in control groups. Extracts with three doses and volatile oil with two lower doses were effective to reduce weight of distal colon (8 cm) as a marker of inflammation and tissue edema. Similarly, MCHE (50, 100, and 200 mg/kg) and MCEO (62.5 and 125 μL/kg) were statistically effective in dip of ulcer index, total colitis index, and MPO activity compared to control groups. 
Conclusion: The beneficial effect of M. communis was comparable with that of prednisolone and mesalazine; however, by its dose escalation, this activity tends to be diminished. This research showed the anti-inflammatory activity of MCHE and MCEO on experimentally induced acute colitis.