In the absence of a catechol group on the galangin, arginase
inhibition declined sharply, suggesting that the catechol group is
important for inhibition activity. The absence of a hydroxyl group
at position 3 and catechol on the apigenin inhibited only 6% of
ARG-L at 125 lM. C-glycosylation on the isoorientin (luteolin-6-
C-glucoside) and the orientin (luteolin-8-C-glucoside) did not en-
hance arginase inhibition. In contrast, the 7,8-dihydroxyflavone
showed an IC50of 12 lM when the hydroxyl at position 3 and