Influence of an additional 2-amino substituent of the 1-aminoethyl pharmacophore group on the potency of rimantadine against influenza virus A

We examined whether the incorporation of a second amino group into the 1-aminoethyl pharmacophore of rimantadine 2 and into the piperidine pharmacophore of the heterocyclic rimantadine 4 was compatible with anti-influenza virus A activity. The new synthetic molecules are capable of forming two hydrogen bonds within the receptor. We identified molecules 8 and 16, bearing the adamantyl and 1,2-diaminoethyl groups, which are equipotent to rimantadine 2 bearing the adamantyl and 1-aminoethyl pharmacophore groups. Interestingly, diamino compound 16 is a 4-fold more potent inhibitor than its parent monoamino heterocyclic rimantadine 4 propably because of additional hydrogen bonding interactions with the M2 protein receptor.