Chemistry. General procedure for the synthesis of 6-carboxyamide-2-aminobenzothiazoles 1a, 1b, 1c, 1e, 2a, 2b, 2c, 2d, 2e, 2f and 2g. A solution of 2-amino-6-benzothiazolcarboxylic acid (1 equiv.) was prepared in anhydrous DMF under a nitrogen atmosphere at 0 • C. To this solution, EDC•HCl (1 equiv.) and HOBt (1 equiv.) were added. The mixture was stirred at 0 • C for 10 minutes. Subsequently, a solution of the appropriate amine (1 equiv.) in anhydrous DMF was added dropwise, followed by the addition of TEA (1 equiv.). The temperature was then allowed to rise spontaneously, and the mixture was stirred overnight at room temperature. After completion, the DMF was removed under reduced pressure, and the residue was suspended in water and extracted with ethyl acetate. The organic layer was washed three times with a saturated solution of Na 2 CO 3 and then with brine, dried over anhydrous Na 2 SO 4 , and concentrated. The crude product was crystallized from DCM or diethyl ether to yield the desired product. (PerkinElmer Inc, US) followed by incubation of the assay plates at 30 • C for 10 min. The reaction was initiated by the addition of 5 µl NADPH (5 mM in ultrapure water) followed by kinetically reading the assay plates at 550 nm using the EnVision® Multilabel Reader at 10, 20, 30, 40 and 50 min. The slope of each assay well was calculated. The screening data was analyzed using ActivityBase (IDBS) and for outlier elimination in the control wells, the 3-σ method was applied. Based on the slope, the data were normalized to the positive control methotrexate for TbPTR1/LmPTR1 (1 µM/50 µM, yielding 100% inhibition) and negative controls (1% DMSO, yielding 0% inhibition) and % inhibition calculated for all samples. The measurement at time 0 min was used to flag optically interfering samples.