Rimantadine derivatives with antiviral activity against flaviviruses and rimantadine-resistant strain of influenza A virus

Pyridine-containing amides of rimantadine (1-(1-adamantyl)ethylamine) were synthesized by the amidation of rimantadine hydrochloride by the corresponding acids in the NEt₃—N,N′-dicyclohexylcarbodiimide (DCC)—4-(N,N-dimethylamino)pyridine (DMAP) system as the analogues of previously described antiviral compounds 1-adamantylmethyl-5-aminoisoxazole-3-carboxylate and N-{[5-(thien-2-yl)isoxazol-3-yl]methyl}adamantane-1-amine. The spectrum of antiviral activity against the rimantadine-resistant A/PR/8/34 strain of influenza A virus, tick-borne encephalitis virus (TBEV) strain Absettarov (European subtype), yellow fever virus (YFV) vaccine strain 17D, and West Nile virus (WNV) strain Strix nebulosa-12 was studied. The structure—activity relationships were discussed. Synthesized compounds efficiently inhibited the reproduction of TBEV and WNV. N-[1-(Adamantan-1-yl)ethyl]picolinamide efficiently inhibited the reproduction of enveloped viruses with both type I (influenza) and type II (flaviviruses) fusion proteins. The antiviral activity against the rimantadine-resistant influenza virus A/PR/8/34 and a low cytotoxicity (high selectivity index) were revealed for N-[1-(adamantan-1-yl)ethyl]-isonicotinamide.