Studies on the trypanocidal activity of semi-synthetic pyran[b-4,3]naphtho[1,2-d]imidazoles from beta-lapachone.

We synthesized new naphthoimidazoles from beta-lapachone with an aromatic moiety linked to the imidazole ring, using phenylic and heterocyclic aldehydes. The most active compound against Trypanosoma cruzi had a p-methyl group linked to the phenyl ring, presenting an EC(50) value of 15.5 +/- 2.9 microM. No reliable correlation could be established with the biological activity and the structure of in the phenylic series. For the heterocyclic series, activity was associated with a three bond-distance from nitrogen to the imidazole ring, in accordance with our previous work.