IC50 values for inhibition by a curcuminoid extract, curcumin, demethoxycurcumin, bisdemethoxycurcumin, and a curcuminoid mixture of CYP3A, CYP2C9, and UGT activities in HLM or intact LS180 cells and SULT activity in HLC or intact LS180 cells Functional activities evaluated included triazolam 1′-hydroxylation (CYP3A), flurbiprofen hydroxylation (CYP2C9), acetaminophen glucuronidation (UGT), and acetaminophen sulfation (SULT). IC50 values from experiments determining the effect of 20-min preincubation on the extent of inhibition of CYP3A-mediated triazolam 1-hydroxylation by curcuminoids are also shown. Shown are the mean ± S.E. of triplicate determinations.
Enzyme | Model System | IC50 Curcuminoid Extract | IC50 Pure Curcumin | IC50 Pure Demethoxycurcumin | IC50 Pure Bisdemethoxycurcumin | IC50 Curcuminoid Mixture |
|---|---|---|---|---|---|---|
| μM | μM | μM | μM | μM | ||
| CYP3A | HLM (no preincubation) | 32.1 ± 0.6 | 58.0 ± 3.5 | 43.5 ± 3.8 | 41.7 ± 3.5 | 36.4 ± 3.8 |
| CYP3A | HLM (preincubation) | 24.1 ± 2.0 | 47.1 ± 2.0 | 31.5 ± 0.5 | 35.3 ± 2.7 | N.D. |
| CYP2C9 | HLM | 13.5 ± 1.4 | >50 | 8.8 ± 1.2 | >50 | 36.3 ± 3.4 |
| SULT | HLC | 0.99 ± 0.04 | 5.9 ± 0.4 | 1.70 ± 0.06 | 0.95 ± 0.02 | 1.36 ± 0.06 |
| SULT | LS180 cells | 5.2 ± 0.6 | 2.6 ± 0.4 | 12.5 ± 0.4 | 5.6 ± 0.8 | 9.6 ± 1.4 |
| UGT | HLM | 133.5 ± 17.9 | N.D. | N.D. | N.D. | N.D. |
| UGT | LS180 cells | 12.1 ± 0.4 | 2.2 ± 0.1 | 13.9 ± 2.3 | 9.8 ± 1.4 | 12.2 ± 1.8 |
N.D., not determined