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

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

CYP Activity IC 50 (µM) K i (µM)
STS Specific inhibitor/reported valuesa STS Specific inhibitor/reported valuesa
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]
  1. “–” Represents the data that is not determined
  2. 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
  3. a IC 50 and K i values of specific inhibitors were referred to the reported literatures
  4. b Represents 95 % confidence interval