A compound was isolated from Murrya koenigii (Linn.) Spreng Wettst by solvent extraction, acid hydrolysis, chromatography followed by crystallization. The compound could exert anti-ulcer activity against ethanol induced gastric ulcer and cysteamine induced duodenal ulcer in albino rats. Infra-red spectroscopy, mass spectroscopy and nuclear magnetic resonance studies revealed that the isolated compound was chemically 1,3,5-trihydroxy-7-methylanthracene-9,10-dione