The present invention relates to novel substituted 2-(5-hydroxy-2-methyl-1H-indol-3-yl)acetic acids, to novel antiviral active ingredients, pharmaceutical compositions, antiviral medicaments, methods for prophylaxis and treatment of viral diseases particularly caused by influenza viruses and infectious hepatisis C (HCV) viruses.Novel substituted 2-(5-hydroxy-2-methyl-1H-indol-3-yl)acetic acids, their esters of the general formula 1 and pharmaceutically acceptable salts and/or hydrates thereof have been disclosedwherein: R1 represents amino group substituent selected from hydrogen, optionally substituted C1-C5 alkyl, acyl or sulfonyl R2 and R4 independently of each other represent alkyl substituent selected from hydrogen, halogen, optionally substituted C1-C3 alkyl, optionally substituted hydroxyl, optionally substituted amino group, optionally substituted aminomethyl, substituted mercapto group R3 represents hydrogen, optionally substituted lower C1-C5 alkyl R5 represents cyclic system substituent selected from hydrogen, fluorine, trifluoromethyl, carboxy group, alkyloxycarbonyl, possibly substituted aryl, heterocyclyl, optionally substituted aminomethyl, cyano group R6 represents hydroxyl group substituent selected from hydrogen, optionally substituted C1-C5 alkyl, acyl.
