Table 2.
Kinetic parameters derived for the oxidation and glucuronidation of isobavachin by HLM, HIM, MLM, MIM, expressed CYP isozymes and recombinant UGT enzymes, respectively (Mean ± SD). All experiments were performed in triplicate
| Enzyme | Meta. | Vmax (pmol/min per mg) | Km (S50) (μM) | Ki (μM) | n | CLint (CLmax) (μl/min per mg) | Model |
|---|---|---|---|---|---|---|---|
|
| |||||||
| HLM | M1 | 508.10 ± 116.90 | 8.50 ± 2.29 | 1.67 ± 0.45 | N.A. | 59.81 ± 21.18 | SI |
| M2 | 12.92 ± 0.46 | 2.34 ± 0.38 | N.A. | N.A. | 5.53 ± 0.93 | MM | |
| M3 | + | + | + | + | + | ||
| HIM | M1 | 257.10 ± 5.62 | 2.74 ± 0.21 | N.A. | N.A. | 93.97 ± 7.65 | MM |
| M2 | 63.34 ± 6.25 | 3.21 ± 0.65 | 77.80 ± 28.51 | N.A. | 19.71 ± 4.43 | SI | |
| M3 | 154.00 ± 3.69 | 3.52 ± 0.29 | N.A. | N.A. | 43.79 ± 3.72 | MM | |
| MLM | M1 | 102.60 ± 4.56 | 2.90 ± 0.47 | N.A. | N.A. | 35.46 ± 5.98 | MM |
| M2 | 216.30 ± 25.66 | 3.36 ± 0.81 | 65.03 ± 25.52 | N.A. | 64.32 ± 17.18 | SI | |
| M3 | 98.22 ± 6.54 | 2.07 ± 0.32 | 101.3 ± 32.28 | N.A. | 47.43 ± 7.99 | SI | |
| MIM | M1 | 237.3 ± 20.1 | 4.17 ± 0.72 | 134.8 ± 58.05 | N.A. | 56.88 ± 10.89 | SI |
| M2 | ++ | ++ | ++ | ++ | ++ | ||
| M3 | 79.5 ± 11.51 | 6.93 ± 1.68 | 46.66 ± 16.41 | N.A. | 11.48 ± 3.25 | SI | |
| CYP1A2 | M1 | 311.60 ± 16.01 | 5.08 ± 0.54 | 96.53 ± 14.82 | N.A. | 61.37 ± 7.22 | SI |
| M2 | ++ | ++ | ++ | ++ | ++ | ||
| M3 | 173.30 ± 61.67 | 19.81 ± 9.47 | 17.76 ± 8.78 | N.A. | 8.75 ± 5.21 | SI | |
| CYP2C19 | M1 | 2517.0 ± 627.9 | 56.54 ± 16.3 | 10.94 ± 3.27 | N.A. | 44.52 ± 16.97 | SI |
| M2 | ++ | ++ | ++ | ++ | ++ | ||
| M3 | 1300.0 ± 325.0 | 16.81 ± 5.02 | 4.48 ± 1.35 | N.A. | 77.33 ± 30.10 | SI | |
| HLM | G1 | 6948.0 ± 345.6 | 23.79 ± 1.36 | N.A. | 1.68 ± 0.15 | 148.79 ± 9.36 | Hill |
| G2 | 1600.0 ± 205.2 | 73.32 ± 11.19 | 30.98 ± 5.48 | N.A. | 21.82 ± 4.35 | SI | |
| HIM | G1 | 1188.00 ± 73.87 | 9.77 ± 1.11 | 134.80 ± 26.42 | N.A. | 121.62 ± 15.80 | SI |
| G2 | 394.90 ± 21.03 | 11.79 ± 1.10 | 123.60 ± 19.12 | N.A. | 33.49 ± 3.59 | SI | |
| MLM | G1 | 4022.0 ± 122.6 | 27.75 ± 1.97 | N.A. | N.A. | 144.94 ± 11.20 | MM |
| G2 | 988.4 ± 179.5 | 33.39 ± 8.14 | 48.7 ± 14.79 | N.A. | 29.60 ± 9.00 | SI | |
| MIM | G1 | 2432.0 ± 381.2 | 18.71 ± 4.52 | 84.26 ± 29.37 | N.A. | 129.98 ± 37.45 | SI |
| G2 | 632.3 ± 40.49 | 10.13 ± 1.16 | 110.10 ± 19.77 | N.A. | 62.42 ± 8.21 | SI | |
| UGT1A1 | G1 | 7735.0 ± 1186.0 | 41.84 ± 8.25 | 40.82 ± 9.70 | N.A. | 184.87 ± 46.18 | SI |
| G2 | ++ | ++ | ++ | ++ | ++ | ||
| UGT1A6 | G1 | 3822.00 ± 782.40 | 67.66 ± 16.32 | 21.97 ± 5.84 | N.A. | 56.49 ± 17.87 | SI |
| G2 | 341.90 ± 55.04 | 31.85 ± 6.28 | 12.71 ± 2.60 | N.A. | 10.73 ± 2.73 | SI | |
| UGT1A7 | G1 | 3593.00 ± 487.20 | 32.91 ± 5.76 | 27.54 ± 5.39 | N.A. | 109.18 ± 24.17 | SI |
| G2 | + | + | + | + | + | ||
| UGT1A8 | G1 | 1607.00 ± 241.00 | 34.71 ± 6.45 | 17.04 ± 3.36 | N.A. | 46.30 ± 11.05 | SI |
| G2 | + | + | + | + | + | ||
| UGT1A9 | G1 | 3167.00 ± 426.4 | 15.63 ± 3.12 | 38.39 ± 8.88 | N.A. | 202.62 ± 48.80 | SI |
| G2 | ++ | ++ | ++ | ++ | ++ | ||
| UGT2B4 | G1 | 81.29 ± 2.05 | 2.66 ± 0.28 | N.A. | N.A. | 30.59 ± 3.28 | MM |
| G2 | + | + | + | + | + | ||
+, under the limit of quantification; ++, unable to determine the kinetic parameters in the absence of a full kinetic profile; Hill, Hill equation; HIM, human intestine microsomes; HLM, human liver microsomes; Meta., metabolites; MIM, mouse intestine microsomes; MLM, mouse liver microsomes; MM, Michaelis–Menten model; N.A., not available; SI, substrate inhibition model.