Table 2.
Inhibition constants, mode of inhibition and effect of preincubation of T. arjuna extracts on CYP3A4, CYP2D6 and CYP2C9 activities in human liver microsomes (n = 3; values ± standard deviation).
| Enzyme | Alcoholic extract of T. arjuna (μg of extract/mL) |
Aqueous extract of T. arjuna (μg of extract/mL) |
||||||
|---|---|---|---|---|---|---|---|---|
| Ki value | Mode of inhibition | Shifted IC50 (μg/mL) – 30 min preincubation with NADPHa,b | Shifted IC50 (μg/mL) – 30 min preincubation without NADPHa,b | Ki value (μg of extract/mL) | Mode of inhibition | Shifted IC50 (μg/mL) – 30 min preincubation with NADPHa,b | Shifted IC50 (μg/mL) – 30 min preincubation without NADPHa,b | |
| CYP3A4 | 24.05 ± 1.82 | Non-competitive | >75 | >75 | 27.06 ± 0.219 | Non-competitive | >75 | >75 |
| CYP2D6 | 17.01 ± 1.28 | Non-competitive | >75 | >75 | 8.33 ± 0.44 | Non-competitive | >75 | >75 |
| CYP2C9 | 23.72 ± 4.7 | Non-competitive | >75 | >75 | 20.56 ± 2.8 | Non-competitive | >75 | >75 |
a
Each data represents the average of triplicate measurements ± standard deviation.
b
Ki value, mode of inhibition and effect of preincubation was determined only for alcoholic and aqueous extract, since they were potent inhibitors and also reported to be used therapeutically.