Table 5.
Apparent Ki values for selected pyrimidine nucleobase analogues as inhibitors of phosphoribosyltransferase activity towards 5-fluorouracil (100 μM). in cytosol extracts of Schistosoma mansoni and mouse liver
| Compound | Apparent Ki (μM) ± S.Ea | Ratiob | |
|---|---|---|---|
|
| |||
| S. mansoni | Mouse Liver | ||
| 5-Azaorotic acid (Oxonic acid) | 0.9 ± 0.2 | 45 ± 16 | 50 |
| Barbituric acid | 35 ± 4 | 23 ± 3 | 0.66 |
| 5-Azabarbituric acid (Cyanuric acid) | 392 ± 59 | 212 ± 34 | 0.54 |
| 6-Carboxymethyluracil | 539 ± 86 | 156 ± 28 | 0.29 |
| 4,6-Dihydroxypyrimidine | 8090 ± 1220 | 15 ± 1 | 0.002 |
a
S.E. = standard error,
b
Ratio of mouse liver apparent Ki to S. mansoni apparent Ki. (data from Iltzsch et al., 1984).