Suppression of inducible nitric oxide synthase by (-)-isoeleutherin from the bulbs of Eleutherine americana through the regulation of NF-κB activity

Su Hyun Song, Hye Young Min, Ah Reum Han, Joo Won Nam, Eun Kyoung Seo, Woo Park Seoung Woo Park, Hyung Lee Sang Hyung Lee, Kook Lee Sang Kook Lee

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28 Scopus citations


Eleutherine americana Merr. et Heyne (Iridaceae) has been used as a folk medicine for the treatment of coronary disorders and wound-healing. In our previous phytochemical study, several pyranonaphthoquinoids, including (-)-isoeleutherin, were isolated from the bulbs of E. americana. Because inhibitors of inducible nitric oxide synthase (iNOS) might be useful as anti-inflammatory agents, we investigated the potential of pyranonaphthoquinoids to inhibit iNOS activity. We found that (-)-isoeleutherin inhibits lipopolysaccharide (LPS)-stimulated induction of nitric oxide (NO) in a dose-dependent manner (IC50 = 7.4 μM). Using western blots and reverse transcription-polymerase chain reaction, we showed that (-)-isoeleutherin suppresses the expression of iNOS protein and mRNA. In addition, (-)-isoeleutherin inhibited the expression of various cytokines such as interleukin-1β and interferon-β. Activation of the transcriptional activity of NF-κB by LPS was also inhibited by treatment with (-)-isoeleutherin, suggesting that (-)-isoeleutherin-mediated suppression of iNOS expression is associated with the regulation of transcription factor NF-κB. These findings suggest that (-)-isoeleutherin might be a novel anti-inflammatory agent, and that it may work by inhibiting NFkB activation in macrophages.

Original languageEnglish
Pages (from-to)298-302
Number of pages5
JournalInternational Immunopharmacology
Issue number3
StatePublished - Mar 2009

Bibliographical note

Funding Information:
This work was supported by grant no. R15-2006-020 from the National Core Research Center (NCRC) program of the Ministry of Education, Science & Technology (MEST) and the Korea Science and Engineering Foundation (KOSEF) through the Center for Cell Signaling & Drug Discovery Research at Ewha Womans University.


  • (-)-Isoeleutherin
  • Anti-inflammatory
  • Eleutherine americana
  • Inducible nitric oxide synthase (iNOS)
  • Nitric oxide (NO)
  • Nuclear factor kappa beta (NF-κB)


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