Table 2. IC50 values for inhibition by curcuminoid extract and piperine of CYP selective activities measured in human liver microsomes.
Functional activities evaluated included triazolam 1′-hydroxylation (CYP3A), flurbiprofen hydroxylation (CYP2C9), S-mephenytoin hydroxylation (CYP2C19), phenacetin de-ethylation (CYP1A2), dextromethorphan demethylation (CYP2D6), chlorzoxazone hydroxylation (CYP2E1), and bupropion hydroxylation (CYP2B6). IC50 values were generated by nonlinear regression curve fitting using Prism software. Also shown are IC50 values for control inhibitors that are known to be relatively specific for each of the CYP isoforms evaluated measured in the same set of human liver microsomes. Shown are the mean ± standard errors of triplicate determinations using HLM from three different individuals.
| Isozyme | IC50 Curcuminoid Extract (μM) | IC50 Piperine (μM) | IC50 Control Inhibitor (μM) | Control Inhibitor |
|---|---|---|---|---|
| CYP3A | 25.3 ± 1.3 | 5.5 ± 0.7 | 0.10 ± 0.04 | Ketoconazole |
| CYP2C9 | 13.5 ± 1.4 | 40.7 ± 4.1 | 0.44 ± 0.03 | Sulfaphenazole |
| CYP2D6 | 63.6 ± 4.8 | >50 | 0.13 ± 0.01 | Quinidine |
| CYP2C19 | 7.4 ± 1.2 | >50 | 6.5 ± 1.3 | Omeprazole |
| CYP1A2 | 95.4 ± 17.1 | 29.8 ± 3.6 | 0.10 ± 0.02 | α-Naphthoflavone |
| CYP2E1 | >200 | >50 | 5.8 ± 0.8 | Diethyldithiocarbamate |
| CYP2B6 | 9.4 ± 1.9 | >50 | 5.0 ± 0.5 | thio-TEPA |