Synthesis and Antiviral Activity of Ethyl 1,2-dimethyl-5-Hydroxy-1 H -Indole-3-carboxylates and Their Derivatives

New substituted ethyl 5-hydroxy-1,2-dimethyl-1H-indole-3-carboxylates and 7,8-dimethyl-1,2,3,7-tetrahydro[1,3]oxazino[5,6-e]indole-9-carboxylates including arbidol analogs in addition to 6-hydroxy-1-methyl-7-pyridin-3-yl-4,5-dihydropyrrolo[4,3,2-de]isoquinolin-3(1H)-ones and 1,4-dimethyl-7-pyridin-3-yl-2-(phenylsulfonylmethyl)-1,4-dihydropyrrolo[4,3,2-de]isoquinoline-3,6-dione were synthesized. Their antiviral activity against influenza A/New Caledonia/20/99 virus (H1N1), bovine viral diarrhea virus (BVDV), and hepatitis C virus (HCV) was studied. It was found that the synthesized compounds were not noticeably active against these viruses. The exceptions were only ethyl 5-hydroxy-4-(dimethylaminomethyl)-1-methyl-6-pyridin-3-yl-2-(phenylsulfinylmethyl)-1H-indole-3-carboxylate and 5-hydroxy-1,2-dimethyl-6-fluoro-1H-indole-3-carboxylate hydrochlorides, which exhibited micromolar activities EC50 = 6.6 and 9.8 iM, respectively, against a human hepatoma cell line (Huh7.3) with increased sensitivity to HCV infection (strain JFH-1, genotype 2a).