Department of Chemistry, Khalkhal Branch, Islamic Azad University, Khalkhal, Iran.

In this study, the ethanol extract of the inner bark of the Syderoxylum obtusifolium (EESob)was tested in the model of cyclophosphamide-induced hemorrhagic cystitis. Male Wistar rats were submitted to the injection of cyclophosphamide, 1 h after the treatment with EESob (200 or 400 mg/kg) or vehicle. After 24 h, the urinary bladder was excised and the edema, myeloperoxidase activity and malondialdehyde formation were measured. Also, myeloperoxidase activity and malondialdehyde formation in lung, spleen and liver and leukocyte counts in the peripheral blood were evaluated. Injection of cyclophosphamide increased myeloperoxidase activity and edema. The former was inhibited by the EESob at 400 mg/kg, but the latter was not affected. Although cyclophosphamide did not alter the bladder malondialdehyde formation, pre-treatment with EESob at both doses markedly increased this parameter. Lung and liver parameters or leukocyte counts were not altered by EESob. The spleen myeloperoxidase activity and malondialdehyde formation were not affected by cyclophosphamide, but were increased by the treatment with EESob. These results suggests that EESob administration to rats decrease myeloperoxidase activity in bladder tissue, but is accompanied by lipoperoxidation in this tissue, as well as in spleen, which do not support the use of EESob to treat cystitis.   Key words: Syderoxylum obtusifolium, cyclophosphamide, inflammation, lipid peroxidation, hemorrhagic cystitis.