Reported Km or S50 values, 4-MU concentrations used in this study, and IC50 values of zafirlukast for the inhibition of 4-MU glucuronidation by human UGT isoforms
The 4-MU concentrations are similar to the reported Km values for each UGT enzyme (Uchaipichat et al., 2004; Fujiwara et al., 2009). Data are the mean ± S.E. of triplicate determinations.
| UGT | Km or S50 | 4-MU Concentration | IC50 |
|---|---|---|---|
| µM | |||
| UGT1A1 | 113a | 100 | 0.7 ± 1.1 |
| UGT1A3 | 1159b | 1000 | 6.3 ± 1.0 |
| UGT1A6 | 109a | 100 | 2.0 ± 1.0 |
| UGT1A8 | 191b | 200 | 1.0 ± 1.1 |
| UGT1A9 | 8.0b | 10 | 0.6 ± 1.1 |
| UGT1A10 | 31a | 100 | 3.0 ± 1.0 |
| UGT2B7 | 335c | 300 | 13.1 ± 1.0 |
| UGT2B15 | 253b | 300 | 33.4 ± 1.0 |