Table 1.

Kinetic analysis of the glucuronidation activity of UGTs against raloxifene

Raloxifene-6-GlucRaloxifene-4′-Gluc
UGTaVmax, pmol/min/μgKM, μmol/LVmax/KM, μL/min/μgVmax, pmol/min/μgKM, μmol/LVmax/KM, μL/min/μg
1A120 ± 38.9 ± 1.92.2 ± 0.211 ± 212 ± 30.95 ± 0.05
1A30.41 ± 0.0221 ± 10.019 ± 0.0020.48 ± 0.043.1 ± 0.30.15 ± 0.02
1A71.9 ± 0.213 ± 30.16 ± 0.026.9 ± 0.422 ± 20.32 ± 0.03
1A8173Ala/277Cys7.0 ± 1.60.31 ± 0.0523 ± 419 ± 52.4 ± 0.47.9 ± 1.0
1A8173Gly/277Cys6.1 ± 1.50.08 ± 0.04b80 ± 18c4.1 ± 1.1c0.76 ± 0.11b5.3 ± 0.9
1A8173Ala/277TyrNo activity detected
1A93.4 ± 0.522 ± 60.16 ± 0.038.3 ± 0.94.5 ± 0.81.9 ± 0.1
1A10No activity detected16 ± 10.21 ± 0.0376 ± 6
  • aNo raloxifene glucuronide formation was observed for homogenates from cells overexpressing UGTs 1A4, 1A6, 2B4, 2B7, 2B10, 2B11, 2B15, or 2B17.

  • bA significant (P < 0.005; cP < 0.01) difference was observed for 1A8173Gly/277Cys- versus 1A8173Ala/277Cys-overexpressing cell homogenates.