UDP-glucuronosyltransferase activities for the N-glucuronidation of 1-substituted imidazole substrates by expressed human UGT1A4
| 1-Substituted Imidazole | UGT1A4 |
|---|---|
| pmol/min/mg | |
| 1-Phenyl ( 1a ) | 27 ± 21-a |
| 1-Benzyl ( 1b ) | 3 ± 0.3 |
| 1-Phenylethyl ( 1c ) | N.D.1-b |
| 1-(4-Methoxyphenyl) ( 1d ) | 72 ± 2 |
| 1-(4-Chlorophenyl) ( 1e ) | 82 ± 4 |
| 1-(4-Bromophenyl) ( 1f ) | 14 ± 0.7 |
| 1-(4-Trifluoromethylphenyl) ( 1g ) | 8 ± 0.7 |
| 1-(4-Nitrophenyl) ( 1h ) | —1-c |
Glucuronidation of the substrates at 1.25 mM concentration by UGT1A4 expressed in human lymphoblastoid cells. Data given as mean ± S.D., n = 3.
↵1-a Value previously published (Vashishtha et al., 2000). Compound 1a was the only compound where catalysis was detected for human UGT1A3 in insect cells following infection with UGT recombinant baculovirus, using the screening method (glucuronidation activity, 35 ± 3 pmol/min/mg of protein).
↵1-b N.D., activity observed, but not quantifiable.
↵1-c No activity detected (below limit of detection, ∼0.5 pmol/min/mg of protein).