3,4-Dihydro-1H-indolo[2,3-b][1,8]naphthyridin-2(10H)-one, is a derivative of 6,7,8,9-Tetrahydro-7-hydroxy-5-methyl-3-phenyl-pyrido[3’,2’:4,5]imidazo[1,2-a]pyrimidinium Chloride (H957770), a carcinogen used in the study of intestinal bacteria metaboism. Created through the heat processing of food.