TABLE 2

Activities of various microsomes and human UGT-isoforms for the glucuronidation of 2′-OH-TCC, 3′-OH-TCC, 6-OH-TCC, and TCC determined by LC-UV (265 nm)

Activities are expressed as pmol · min−1 · mg protein−1 as the mean and S.D. of three independent measurements.

Microsomes/UGT-Isoform2′-OH-TCC6-OH-TCC3′-OH-TCCTCC
N-GlucN′-Gluc
RLM2600 ± 1305500 ± 18008700 ± 2800n.d.n.d.
HLM2700 ± 6808500 ± 22005200 ± 150n.d.*,+n.d.*,++
CLM22800 ± 10016300 ± 7009500 ± 1500n.d.*,++n.d.*,++
MLM2600 ± 6507900 ± 240014700 ± 690n.d.*,++n.d.*,++
HKM5600 ± 17007700 ± 6104200 ± 30n.d.*,+++n.d.*,+++
HIM5700 ± 12003900 ± 14007100 ± 600n.d.n.d.
1A1850 ± 210820 ± 260520 ± 20n.d.n.d.
1A3390 ± 93410 ± 50540 ± 70n.d.n.d.
1A4n.d.n.d.n.d.n.d.n.d.
1A6n.d.n.d.n.d.*n.d.n.d.
1A7870 ± 4401100 ± 3201700 ± 160n.d.n.d.
1A85700 ± 22005000 ± 11009400 ± 250n.d.n.d.
1A91200 ± 8002400 ± 680840 ± 190n.d.*,+n.d.*,++
1A10210 ± 160280 ± 150<LOQn.d.n.d.
2B4n.d.n.d.*n.d.n.d.n.d.
2B7<LOQ<LOQn.d.*n.d.n.d.
2B15n.d.n.d.n.d.n.d.n.d.
2B17n.d.n.d.n.d.n.d.n.d.

  • <LOQ (limit of quantitation), glucuronide peak < LOQ of LC-UV detection (0.2 μM); n.d. (not determined because no reference compound was available), glucuronide peak < LOQ of LC-UV detection (60 nM).

  • ↵* Low product amounts detected by ESI-MS.

  • ↵+, ++, +++ , The activity for the N-glucuronidation is rated semiquantitatively [from low (+) to high (+++)] based on the peak height in the ESI-MS signal.