Table II.

Inhibitory effect of PPD12 on major CYP metabolic activities in human liver microsomes.

			IC50 (µM)
CYP enzyme	Catalysis	Inhibitor	Inhibitor	PPD12
3A4	Midazolam 1′-hydroxylation	Ketoconazole	0.0040	1.03
3A4	Testosterone 6-β-hydroxylation	Ketoconazole	0.0154	8.43
1A2	Phenacetin 0-deethylation	α-Naphthoflavone	0.0168	>33
2B6	Bupropion hydroxylation	Ticlopidine	0.0823	2.21
2C8	Amodiaquine N-deethylation	Quercetin	0.7319	9.57
2C9	Diclofenac4′-hydroxylation	Sulfaphenazole	0.0856	>33
2C19	S-mephenytoin4′-hydroxylation	Ticlopidine	0.5120	15.04
2D6	Dextromethorphandextrorphan	Quinidine	0.0235	11.85

PPD12, 20(S)-protopanaxadiol derivative; CYP, cytochrome P450.