A set of new derivatives of 4,8-disubstituted pyrimido[5,4-d]pyrimidines were efficiently synthesized and in vitro evaluated against Trypanosoma brucei and Leishmania infantum promastigotes and intramacrophage amastigotes. The in vitro cytotoxicity was determined using the THP-1 cell line, and early in vitro ADME-Tox was carried out using in vitro assays for cytotoxicity (A549 and HEK293 cell lines) and CYP3A4 ...