Table 3. IC50 values for inhibition by a curcuminoid extract, curcumin, demethoxycurcumin, bisdemethoxycurcumin, and a curcuminoid mixture of CYP3A, CYP2C9, and UGT activities in human liver microsomes (HLM) or intact LS180 cells and SULT activity in human liver cytosol (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 minute preincubation on the extent of inhibition of CYP3A-mediated triazolam 1-hydroxylation by curcuminoids are also shown. Shown are the mean ± standard errors of triplicate determinations.
| Enzyme | Model System | IC50 Curcuminoid Extract (μM) | IC50 Pure Curcumin (μM) | IC50 Pure Demethoxycurcumin (μM) | IC50 Pure Bis- demethoxycurcumin (μM) | IC50 Curcuminoid Mixture (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 | ND |
| 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 | ND | ND | ND | ND |
| UGT | LS180 cells | 12.1 ± 0.4 | 2.2 ± 0.1 | 13.9 ±2.3 | 9.8 ± 1.4 | 12.2 ± 1.8 |
ND: not determined