The inhibition of ARG-L increased due to the hydroxylation of
the phenyl group of molecules hydroxylated at positions 3, 5,
and 7, such as in galangin (IC50 100 lM), kaempferol (IC50
50 lM) and quercetin (IC504.3 lM). Galangin is not hydroxylated,
kaempferol is hydroxylated at position 40(phenol group), and
quercetin is hydroxylated at positions 30and 40, generating a cate-
chol group. The inhibition activity of quercetin is not significantly
altered if the hydroxyl at position 3 is conjugated with glucose to
generate isoquercitrin, but it loses half of its potency if this posi-
tion is conjugated with rhamnose, as in quercitrin (da Silva et al.,
2012a).