Xanthine Oxidase: Isolation, Assays of Activity, and Inhibition

Table 3

IC₅₀ values of flavonoids and allopurinol for inhibition of XO.

Compounds	XO IC50 (µM) ± SD
(±)-Taxifolin	>100
(+)-Catechin	>100
(−)-Epicatechin	>100
(−)-Epigallocatechin	>100
4′-Hydroxyflavanone	>30
Naringenin	>50
7-Hydroxyflavanone	38.0 ± 7.0
Chrysin	0.84 ± 0.13
Apigenin	0.70 ± 0.23
Luteolin	0.55 ± 0.04
Baicalein	2.79 ± 0.01
3-Hydroxyflavone	>100
Galangin	1.80 ± 0.07
Kaempferol	1.06 ± 0.03
Quercetin	2.62 ± 0.13
Fisetin	4.33 ± 0.19
Morin	10.1 ± 0.70
Myricetin	2.38 ± 0.13
Allopurinol	0.24 ± 0.01
Luteolin + epigallocatechin (1 : 1)	0.76 ± 0.08