title: Inhibition of inducible nitric oxide synthase by sumaflavone isolated from Selaginella tamariscina.
abstract: We previously reported that amentoflavone isolated from Selaginella tamariscina inhibits the production of nitric oxide (NO) in macrophages via nuclear factor-kappaB (NF-kappaB) inactivation. Here, we isolated two other bi-flavonoid compounds (sumaflavone and robustaflavone) from Selaginella tamariscina and studied their effects on inducible nitric oxide synthase (iNOS) gene expression. Sumaflavone inhibited NO production in a concentration-dependent manner and blocked the lipopolysaccharide (LPS)-induced expression of iNOS. In contrast, robustaflavone only marginally affected iNOS gene expression and NO production. To identify the transcriptional factors affected by sumaflavone, we investigated NF-kappaB and AP-1 activation. Reporter gene analysis using AP-1-specific luciferase reporter and gel shift analysis showed that enhanced AP-1 activity by LPS was significantly diminished in macrophages pretreated with sumaflavone. However, sumaflavone did not inhibit LPS-inducible NF-kappaB reporter activity. Western blot analyses also confirmed that the extent of I-kappaBalpha phosphorylation and the nuclear level of p65 were unaffected by sumaflavone. These results suggest that the inhibitory effect of sumaflavone on AP-1 activation may be associated with the potent NO blocking and anti-inflammatory effects of Selaginella tamariscina extract.
authors.affiliation: College of Pharmacy, Chosun University, Gwangju 501-759, Republic of Korea.
authors.forename: Jin Won
authors.initials: JW
authors.lastname: Yang
authors.forename: Yuba Raj
authors.initials: YR
authors.lastname: Pokharel
authors.forename: Mi-Ran
authors.initials: MR
authors.lastname: Kim
authors.forename: Eun-Rhan
authors.initials: ER
authors.lastname: Woo
authors.forename: Hoo Kyoon
authors.initials: HK
authors.lastname: Choi
authors.forename: Keon Wook
authors.initials: KW
authors.lastname: Kang
mesh_terms: D015153:Blotting, Western; D002460:Cell Line; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D047309:Flavones / Q000302:isolation & purification / Q000494:pharmacology*; D006801:Humans; D052247:Nitric Oxide Synthase Type II / Q000037:antagonists & inhibitors*; D032503:Selaginellaceae / Q000737:chemistry*; D018808:Transcription Factor AP-1 / Q000378:metabolism
chemical_list: D004791:Enzyme Inhibitors; D047309:Flavones; D018808:Transcription Factor AP-1; C515650:sumaflavone; D052247:Nitric Oxide Synthase Type II