Structure-activity relations of inhibitory effects of various flavonoids on lipopolysaccharide-induced prostaglandin E2 production in rat peritoneal macrophages: comparison between subclasses of flavonoids.

A study of the structure-activity relations of the inhibitory effect of flavonoids on lipopolysaccharide (LPS)-induced prostaglandin production was carried out via a comparative examination of 39 flavonoids and related compounds. A comparison of the subclasses showed that flavones were most effective, followed by flavanones. Flavonols were less effective than those two groups. These results suggest that the C2-C3 double-bond and 4-oxo functional group of the C-ring are important factors for the high inhibition activities. Flavonoids showed the strongest inhibitory effect on the expression of Cox-2 protein. These results help to explain part of the reason for the pharmacological efficacy of flavonoids as anti-inflammatory compounds.