Anti-Inflammatory Effects of New Flavonoids from Streptomyces sp. BT01 in Lipopolysaccharide-Stimulated RAW 264.7 Murine Macrophages via Inhibition of NF-KappaB Activation

Most flavonoids are known to have anti-oxidant, anti-bacterial and analgesic properties. In this study, the new flavonoids, 7-methoxy-3,3’,4’,6-tetrahydroxyflavone (1) and 2’,7-dihydroxy-4’5’-dimethoxyisoflavone (2) isolated from Streptomyces sp. BT01 inhibited the pro-inflammatory mediators including cytokines by blocking nuclear factor-kappaB (NF-κB) signalling in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. These flavonoids suppressed mRNA and protein expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in LPS-stimulated RAW 264.7 cells. The molecular mechanism was associated with the inhibition of NF-κB activation. These results suggest that these flavonoids have anti-inflammatory effects by suppressing expression of iNOS, COX-2 and cytokines by blocking the NF-κB signalling in LPS-stimulated RAW 264.7 cells.