DHFR-IN-20 (Compound LA1) is a Plasmodium falciparum dihydrofolate reductase (DHFR) inhibitor, with K i s of 0.16, 0.30, 6.6 nM for Pf DHFR-WT, Pf DHFR-QM, Hs DHFR. DHFR-IN-20 has antimalarial activities (IC 50 : 1.4 nM and 1.6 μM for P. falciparum carrying the wild-type (TM4/8.2) and the quadruple mutant (V1/S) Pf DHFR enzyme.