Colitis was induced in male F344/Du rats by daily treatment with 2.3% DSS solution in drinking water for 7 days. BTZO-15 was orally administered to rats at the indicated doses of 0.1, 0.3, 1, 3, and 10 mg/kg (b.i.d.) for 4 days from experimental day 3 to 6 (A). Body weight (B) was measured every day. At experimental day 7, the rats were sacrificed, and large intestine length (C), rectum weight (D), diarrhea score (E), bleeding score (F), and MPO activity (G) underwent a double blind evaluation. All data except body weight shown are mean ± S.E.M. Body weight data shown are means, n = 8. ** P≤0.01: compared the DSS (−) vehicle control group with DSS (+) vehicle control group using Student's t test, and # P≤0.025: compared the DSS (+) vehicle control group with DSS (+) + BTZO-15 treated groups by one-tailed Williams's test (C and D). **P≤0.01: compared the DSS (−) vehicle control group with DSS (+) vehicle control group using Wilcoxon test, and # P≤0.025: compared the DSS (+) vehicle control group with DSS (+) + BTZO-15 treated groups by one-tailed Shirley-Williams test (E and F). ** P≤0.01: compared the DSS (−) vehicle control group with DSS (+) vehicle control group with Aspin-Welch test, and # P≤0.025: compared the DSS (+) vehicle control group with DSS (+) + BTZO-15 treated groups with one-tailed Williams's test (G).