The invention relates to inhibitors of dihydrotolate reductase and pharmaceutical preparations thereof. The invention further relates to methods of treatment of parasitic infections, such as T. gondii, T. cruzi, P. falciparum, T. hrucei, or L. major infections, using the novel inhibitors of the invention.La invencion se refiere a inhibidores de dihidrofolato reductasa y preparaciones farmaceuticas de los mismos; la invencion se refiere, ademas, a metodos de tratamiento de infecciones parasitarias, tales como infecciones por T. gondii, T. cruzi, P. falciparum, T. brucei o L. major, usando los inhibidores novedosos de la invencion.