TABLE 3

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 SourceM-1M-2
VmaxKmVmax/KmVmaxKmVmax/Km
nmol/min/mg proteinμMμl/min/mg proteinnmol/min/mg proteinμMμl/min/mg protein
HLM25.3 ± 0.3122 ± 4.021918.8 ± 0.3103 ± 4.2183
RLM54.9 ± 3.1165 ± 1433319.0 ± 0.556.6 ± 5.4335
PLM114 ± 18217 ± 21526152 ± 13175 ± 17866
HIM13.5 ± 0.2199 ± 6.265.56.9 ± 0.2161 ± 8.342.5
UGT1A912.4 ± 0.360.5 ± 3.92078.1 ± 0.244.3 ± 4.1183
UGT1A615.6 ± 0.374.4 ± 4.12087.4 ± 0.374.4 ± 8.899