The World Health Organization has identified 17 Neglected Tropical Diseases (NTDs) that pose a health burden to over 1.4 billion people. Parasites of the trypanosomatid family are responsible for two potentially lethal insect-vector borne NTDs: Human African Trypanosomiasis (HAT, sleeping sickness), caused by Trypanosoma brucei, and leishmaniasis, caused by the intracellular parasite Leishmania spp. Current therapeutics are limited by toxicity, poor efficacy and parasite resistance, thus underlining the need for new chemotherapies. New anti-parasitic agents can be identified by target-based drug design strategies. The folate pathway enzyme dihydrofolate reductase (DHFR) is a known anti-cancer, anti-bacterial and anti-malarial target. It provides reduced folates, which are crucial to biological processes like DNA, protein and amino acid synthesis or one-carbon transfer. In trypanosomatids, DHFR inhibition, for example by methotrexate (MTX, 1a), is ineffective due to a metabolic bypass via the biopterin-reducing pteridine reductase 1 (PTR1, Figure ): when DHFR is inhibited, PTR1 is overexpressed and sustains sufficient reduced folate levels to ensure parasite survival. Thus, when targeting the folate pathway in Leishmania, both DHFR and PTR1 need to be considered. In T. brucei, RNA interference studies have suggested PTR1 to be a potential anti-parasitic target in its own right. Nonetheless, even nanomolar PTR1 inhibitors have so far shown limited anti-parasitic activity in vitro , suggesting that targeting the T. brucei folate pathway may also benefit from the consideration of both PTR1 and DHFR.