Table 1.

Steady-state kinetic parameters for the inhibition of xanthine oxidase.

				kcat (s−1)	Km (μM)	kcat/Km (μM−1·s−1)	Ki (μM)
Luteolin							1.9 ± 0.7
		10 μM		6.2 ± 0.2	31 ± 5	0.20
		25 μM		3.8 ± 0.2	127 ± 20	0.03
		50 μM		2.6 ± 0.2	164 ± 30	0.02
	Incubation			5.8 ± 0.5	126 ± 30	0.05
			Control	12.1 ± 0.6	3.5 ± 0.8	3.5
Quercetin							1.2 ± 0.7
		10 μM		5.9 ± 0.2	3.7 ± 0.3	1.6
		25 μM		4.5 ± 0.4	43 ± 10	0.10
		50 μM		1.9 ± 0.2	106 ± 30	0.02
	Incubation			4.3 ± 0.8	104 ± 50	0.04
			Control	10.5 ± 0.4	1.2 ± 0.3	8.8
Curcumin
		10 μM		13.3 ± 0.6	2.8 ± 0.6	4.8
		25 μM		11.8 ± 0.4	1.8 ± 0.3	6.5
		50 μM		12.2 ± 0.5	2.4 ± 0.5	5.1
	Incubation			12.4 ± 0.8	3.2 ± 0.9	3.9
			Control	12.4 ± 0.4	2.1 ± 0.4	5.9
Silibinin
		10 μM		5.0 ± 0.3	36 ± 8	0.14
		25 μM		4.0 ± 0.4	30 ± 10	0.13
		50 μM		4.3 ± 0.3	39 ± 10	0.11
	Incubation			3.8 ± 0.1	53 ± 7	0.07
			Control	10.9 ± 0.4	1.9 ± 0.3	5.6
Allopurinol
		10 μM		8.1 ± 0.6	25 ± 7	0.32
		25 μM		6.5 ± 0.6	43 ± 20	0.15
		50 μM		6.9 ± 0.5	63 ± 20	0.11
	Incubation			1.3 ± 0.3	189 ± 90	0.007
			Control	10.1 ± 0.8	3.1 ± 1.0	3.3