 36 naturally occurring flavonoids and related compounds were systematically investigated for their effects on NO production in macrophages exposed to an inflammatory stimulus, revealing that eight active compounds inhibited INOS protein and mRNA expression, as well as the activation of NFB and STAT-1 transcription factors, which partially explains the pharmacological efficacy of flavonoids as anti-inflammatory compounds. This article was offered by Marie Hamelainin, Renan Naminin, Piafoella, and others.