Table 1

Correlation between DDB metabolism and marker enzyme activities in human liver microsomes

P450 Activity	Metabolites
P450 Activity	M1	M2	M3	M4	M5
Testosterone 6β-hydroxylation (CYP3A)	0.931	0.894	0.422	0.206	0.806
Chlorzoxazone 6-hydroxylation (CYP2E1)	0.186	0.182	0.130	0.150	0.142
Dextromethorphan O-demethylation (CYP2D6)	0.146	0.152	0.059	0.035	0.208
S-Mephenytoin 4-hydroxylation (CYP2C19)	0.002	0.071	0.064	0.072	0.038
Tolbutamide methylhydroxylation (CYP2C9)	0.538	0.513	0.179	0.210	0.468
Coumarin 7-hydroxylation (CYP2A6)	0.075	0.158	0.022	0.061	0.089
Caffeine N3-demethylation (CYP1A)	0.002	0.021	0.479	0.780	0.049
7-Ethoxyresorufin O-dealkylation (CYP1A)	0.005	0.001	0.472	0.674	0.099

10 different human liver microsomes were used for the experiments.