Table 2

Effect of flavonoids on the ATPase activity of purified reconstituted MRP1

Condition	Concentration	ATPase Activity
	μM	% control
Control		100 ± 1.2
Quercetin	10	78 ± 1.4^2-150
	50	63 ± 10^2-150
Naringenin	10	101 ± 5
	50	109 ± 1.9^2-150
Naringenin ⁺ 3 mM GSH	10	99 ± 1.9
	50	116 ± 11^2-150
Kaempferol	10	101 ± 4
	50	109 ± 1.6^2-150
GSH	3000	102 ± 5
GSSG	500	118 ± 2^2-150

MRP1 proteoliposomes were incubated at 37°C for 4 h in 0.1 ml of buffer containing 50 mM Tris-HCl, pH 7.4, 5 mM MgCl₂, 2.5 mM ATP, and flavonoids dissolved in DMSO. In reactions containing GSH, DTT (3 mM) was also added. In the experiments shown, vehicle control ATPase activity was 5 to 10 nmol min⁻¹ mg⁻¹ MRP1. Numbers represent mean values (± S.D.) of three independent experiments.

↵2-150 Statistically different from the vehicle control (p < 0.05) (Student's t test).