Kinetics of cytochrome P450 enzymes for metabolism of sodium tanshinone IIA sulfonate in vitro

Chinese Medicine

Table 2 IC ₅₀ and K _i values of STS against human CYP isoforms compared with that of specific inhibitors reported in literature

CYP	Activity	IC ₅₀ (µM)		K _i (µM)
CYP	Activity	STS	Specific inhibitor/reported values^a	STS	Specific inhibitor/reported values^a
CYP1A2	Phenacetin O-deethylation	>100	FUR/1.4 [23]	–	FUR/3 [21]
CYP2A6	Coumarin 7-hydroxylation	>100	TRA/0.42 ± 0.07 [24]	–	TRA/0.17 [24]
CYP2C9	Tolbutamide 4-hydroxylation	>100	SUL/0.3–1.5 [23, 25]	–	SUL/0.3 [21]
CYP2D6	Metoprolol α-hydroxylation	>100	QUI/0.02–0.68 [23, 25]	–	SUL/0.027–0.4 [21, 26, 27]
CYP2E1	Chlorzoxazone 6-hydroxylation	>100	DIE/21.30 [23]	–	CHL/12 [28]
CYP2C19	S-Mephenytoin 4-hydroxylation	>100	TCL/0.52–1.6 [25]	–	TCL/1.2 ± 0.5 [21]
CYP3A4	Midazolam 1-hydroxylation	6.377 (5.536, 7.347)^b	KET/0.08–0.24 [21]	3.183 (0.184, 6.95)^b	KET/0.015 [21]

“–” Represents the data that is not determined
STS sodium tanshinone II A sulfonate; FUR furafylline; TRA trans-2-phenylcyclopropylamine hydrochloride; SUL sulfaphenazole; QUI quinidine; CHL chlormethiazole hydrochloride; TIC ticlopidine hydrochloride; KET ketoconazole; DIE diethyldithiocarbamate
^a IC ₅₀ and K _i values of specific inhibitors were referred to the reported literatures
^b Represents 95 % confidence interval

ISSN: 1749-8546