Metabolite identification of Compound 19. Representative chromatography (A); MS/MS spectrum of parent Compound 19 (B); M-1, M-3, and M-4, demethylation & monohydroxylation (C); M-2 and M-6, dimethylbenzimidazole monohydroxylation (D); M-5, methylbenzene dihydroxylation (E); M-7, demethylation (F); and M-8, methylbenzene monohydroxylation (G).