Fig 1.
(A and B) Chemical structures of two novel tetrahydrophthalazinone PDE inhibitors, CpdA (19) and CpdB, with their IC50s against recombinant TbrPDEB1 (G. J. Sterk, personal communication). (C) Representative dose-response curves of trypanosome killing by both PDE inhibitors and two cell-permeable cAMP analogues assayed against wild-type bloodstream form T. brucei brucei Lister 427 strain (solid lines, filled symbols) and the CpdA-resistant R0.8 strain (dashed lines; unfilled symbols). See Table 1 for mean EC50s.