Kinetic parameters of daphnetin glucuronidation in microsomes obtained from humans, experimental animals (n = 5), and recombinant UGT1A9 and UGT1A6
Daphnetin was incubated with microsomes (0.1 mg/ml) and UDPGA (5 mM) for 10 min. The kinetic parameters were calculated with Origin software.
| UGT Source | M-1 | M-2 | ||||
|---|---|---|---|---|---|---|
| Vmax | Km | Vmax/Km | Vmax | Km | Vmax/Km | |
| nmol/min/mg protein | μM | μl/min/mg protein | nmol/min/mg protein | μM | μl/min/mg protein | |
| HLM | 25.3 ± 0.3 | 122 ± 4.0 | 219 | 18.8 ± 0.3 | 103 ± 4.2 | 183 |
| RLM | 54.9 ± 3.1 | 165 ± 14 | 333 | 19.0 ± 0.5 | 56.6 ± 5.4 | 335 |
| PLM | 114 ± 18 | 217 ± 21 | 526 | 152 ± 13 | 175 ± 17 | 866 |
| HIM | 13.5 ± 0.2 | 199 ± 6.2 | 65.5 | 6.9 ± 0.2 | 161 ± 8.3 | 42.5 |
| UGT1A9 | 12.4 ± 0.3 | 60.5 ± 3.9 | 207 | 8.1 ± 0.2 | 44.3 ± 4.1 | 183 |
| UGT1A6 | 15.6 ± 0.3 | 74.4 ± 4.1 | 208 | 7.4 ± 0.3 | 74.4 ± 8.8 | 99 |