Correlation of CYP2B6 content with various CYP-catalyzed activities in a panel of human liver microsomes
| Activity5-a | CYP Isoforms Involved | r2 | n |
|---|---|---|---|
| Total CYP | 0.15 | 14 | |
| Cytochrome creductase | 0.01 | 14 | |
| EthoxycoumarinO-deethylase | Multiple | 0.62** | 14 |
| Phenacetin O-deethylase | CYP1A2 | 0.00 | 14 |
| Coumarin 7-hydroxylase | CYP2A6 | 0.64** | 14 |
| Mephenytoin 4′-hydroxylase | CYP2C19 | 0.04 | 14 |
| DextromethorphanO-demethylase | CYP2D6 | 0.07 | 14 |
| Chlorzoxazone 6-hydroxylase | CYP2E1 | 0.13 | 14 |
| Testosterone 6β-hydroxylase | CYP3A4 | 0.335-150 | 21 |
| Lauric acid ω-hydroxylase | CYP4A | 0.17 | |
| Methoxychlorortho-hydroxylase | CYP2B6, CYP1A2, CYP3A4,5-bCYP2C195-c | 0.53** | 17 |
↵5-150 Indicates statistical significance, p < .01; ** p < .001.
↵5-a Isoform-specific catalytic activities were measured by the vendor (IIAM, Exton, PA), except for 7 additional livers (of 21 total), for which we determined testosterone 6β-hydroxylase and 17 livers for which we determined methoxychlor ortho-hydroxylase activities.
↵5-b CYP3A4 contributes to total ortho-hydroxylase activity only after demethylation by CYP1A2 and CYP2C19 (Stresser and Kupfer, 1998a).
↵5-c Inferred from studies with purified recombinant CYP2C19.