Table 5. Effect of folate and thymidine on sensitivity of T. brucei to DHFR-TS inhibitors in vitro.

Inhibitor	No addition	+ Thymidine	+ Folate	+ Thymidine + Folate
Methotrexate	0.012 ± 0.001	0.12 ± 0.03	1.31 ± 0.13	8.16 ± 2.78
Trimetrexate	0.32 ± 0.02	2.82 ± 0.36	1.23 ± 0.06	4.09 ± 0.35
Pyrimethamine	2.26 ± 0.32	2.01 ± 0.34	6.32 ± 0.71	6.87 ± 0.33
Trimethoprim	48.8 ± 3.7	59.8 ± 8.6	170 ± 28	145 ± 22
Raltitrexed	0.038 ± 0.001	> 250	64.8 ± 4.3	> 250
Pemetrexed	0.020 ± 0.001	> 250	12.9 ± 1.1	>250
Nolatrexed	33.8 ± 3.7	32.7 ± 4.7	21.8 ± 2.0	39.6 ± 7.2

Cells were cultured in TBM with the addition of thymidine (160 μM) and/or folate (9 μM) as described in Experimental section. Units for EC₅₀ values are μM. Results are the weighted means ± standard error of 3 independent experiments