A new compound, 1-(2-methyl-4-methoxyphenyl)-4-[(3-hydroxypropyl)amino]-6-methyl-2,3-dihydropyrrolo[3,2-c]quinoline (DBM-819), given intraduodenally in pylorus-ligated rats, inhibited basal acid secretion with an ED(50) value of 3.5 mg/kg. In addition, DBM-819 reduced histamine- and pentagastrin-stimulated gastric acid secretion with ED(50) values of 4.0 and 5.1 mg/kg, respectively. The duration of the anti-secretory effect was approximately 18 h when DBM-819 was administered orally to rats with a chronic gastric fistula. Oral administration of DBM-819 protected against gastric lesions induced by ethanol, NaOH, indomethacin and aspirin, and the duodenal ulcer induced by cysteamine, in a dose-dependent manner with ED(50) values of 7.0, 20, 3.1, 4.0 and 6.0 mg/kg, respectively. Taken together, these results suggest that DBM-819 acts as an effective oral anti-ulcer agent in vivo, and that DBM-819 could be developed as a new therapeutic agent for peptic ulcer disease.