InChI=1/C16H14N2O4/c1-22-16(21)18-12-5-3-2-4-8(12)9-6-10-11(7-13(9)18)15(20)17-14(10)19/h2-5,10-11H,6-7H2,1H3,(H,17,19,20 methyl 1,3-dioxo-2,3,3a,4,10,10a-hexahydropyrrolo[3,4-b]carbazole-5(1H)-carboxylate pyrrolo[3,4-b]carbazole-5(1H)-carboxylic acid, 2,3,3a,4,10,10a-hexahydro-1,3-dioxo-, methyl ester