Abstract
In inflammation, bacterial products and proinflammatory
cytokines induce the formation of large amounts of nitric oxide (NO)
by inducible nitric oxide synthase (iNOS), and compounds that
inhibit NO production have anti-inflammatory effects.
In the present study, we systematically investigated the effects of 36 naturally occurring flavonoids and
related compounds on NO production in macrophages exposed to an inflammatory stimulus
(lipopolysaccharide, LPS), and evaluated the mechanisms of action of the effective compounds.
Flavone, the isoflavones daidzein and genistein, the flavonols isorhamnetin, kaempferol and quercetin,
the flavanone naringenin, and the anthocyanin pelargonidin inhibited iNOS protein and mRNA
expression and also NO production in a dose-dependent manner. All eight active compounds
inhibited the activation of nuclear factor-