Table 4.
Evaluation of heteroaryl replacements of the distal phenyl of 2 on DHFR inhibition, selectivity, solubility, human liver microsomal clearance and MDCK-MDR1 permeability.
 |
|||||||
|---|---|---|---|---|---|---|---|
| Compound | R2 |
TgDHFRa IC50 (nM) |
hDHFRa IC50 (nM) |
Selectivityb | Solubilityc (μM) |
HLMd (CLint) |
MDR1-MDCKe |
| 22 | 2-pyridine | 10.3 ± 1.6 | 1360 ± 210 | 132 | 12 | 17.7 | -- |
| 23 | 3-pyridine | 2.68 ± 0.12 | 300 ± 55 | 112 | -- | -- | -- |
| 24 | 4-pyridine | 4.34 ± 0.43 | 468 ± 32 | 108 | 2.2 | 18.7 | 17.4 (0.86) |
| 25 | 2-pyrimidine | 27.3 ± 2.3 | 1300 ± 51 | 47.6 | 180 | <8.6 | 31.7 (0.80) |
| 26 | 5-pyrimidine | 4.75 ± 0.34 | 1430 ± 100 | 301 | >200 | <8.6 | 20.2 (1.2) |
| 27 | 2-pyrazine | 10.3 ± 0.39 | 1330 ± 50 | 129 | 1.6 | <8.6 | 19.3 (0.77) |
| 28 | 4-pyridazine | 6.00 ± 0.70 | 1100 ± 130 | 185 | 5.7 | <8.6 | 6.40 (3.8) |
a
Average of at least 3 independent replicates ± SEM.
b
Selectivity index (SI) is the hDHFR IC50/TgDHFR IC50, determined within the same experiment.
c
Kinetic solubility.
d
HLM human liver microsomes, CLint intrinsic clearance (mL/min/kg),
e
A:B permeability (papp 10−6 cm/sec), where ER is efflux ratio defined as permeability in A:B/B:A directions.