In vitro studies identified antifolate inhibitors ofLeishmania major Ptr1 that could be used withDhfr inhibitors to help treat parasitic infection. Incultured L. major, five Ptr1-targeting compoundsshowed efficacy against the parasite in combinationwith the Dhfr inhibitor pyrimethamine. One of thePtr1-targeting compounds also showed efficacy asmonotherapy. Ongoing studies include developingcompounds to use in tandem with the inhibitors.