Synthesis of biflavones having a 6-O-7'' linkage and effects on cyclooxygenase-2 and inducible nitric oxide synthase.

In order to establish anti-inflammatory potential of biflavonoids, 17 biflavone derivatives having a 6-O-7'' linkage were synthesized and their effects on cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) were evaluated. The basic molecule (6-O-7'' biflavone) potently inhibited COX-2-mediated PGE(2) production (IC(50): <2 microM), being less active on iNOS-mediated NO production (IC(50): >50 microM) from lipopolysaccharide-treated RAW 264.7 cells, a mouse macrophage cell line. Generally, the hydroxyl/methoxyl substitution(s) on the basic biflavone (6-O-7'') reduced the inhibitory activity of PGE(2) production, while the effects on NO production were varied. It is suggested that the basic biflavone (6-O-7'') may have a potential for new anti-inflammatory agent.