Planta Med 2016; 82(S 01): S1-S381
DOI: 10.1055/s-0036-1596860
Abstracts
Georg Thieme Verlag KG Stuttgart · New York

5,7-Dihydroxyflavone analogues may regulate lipopolysaccharide-induced inflammatory responses by suppressing IκBα-linked Akt and ERK5 phosphorylation in RAW 264.7 macrophages

A Nishina
1   College of Science and Technology, Nihon University, Chiyoda-ku, Tokyo 101 – 0062, Japan
,
M Ukiya
1   College of Science and Technology, Nihon University, Chiyoda-ku, Tokyo 101 – 0062, Japan
,
M Fukatsu
1   College of Science and Technology, Nihon University, Chiyoda-ku, Tokyo 101 – 0062, Japan
,
M Koketsu
2   Department of Materials Science and Technology, Faculty of Engineering, Gifu University, Gifu, 501 – 1112, Japan
,
M Ninomiya
2   Department of Materials Science and Technology, Faculty of Engineering, Gifu University, Gifu, 501 – 1112, Japan
,
D Sato
3   Department of Biomedical Information Engineering, Graduate School of Medical Science, Yamagata University, Yamagata, 990 – 2332
,
H Kimura
4   National Institute of Infectious Diseases, Musashimurayama-shi, Tokyo, 208 – 0011, Japan
› Author Affiliations
Further Information

Publication History

Publication Date:
14 December 2016 (online)

 
 

    The generally mild anti-inflammatory activity of flavonoids makes it difficult to elucidate their reaction mechanisms and structure-activity relationships, despite many reports on the anti-inflammatory activity of isolated or synthesized flavonoids. Here, we studied the anti-inflammatory activity of twelve 5,7-dihydroxyflavone analogues (Figure 1) in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages [1]. The compounds' cytotoxicity was examined using a modified MTT assay. In addition, nitric oxide (NO) and prostaglandin E2 (PGE2) production in the cells was measured by the Griess reagent method and ELISA, respectively. Various proteins were detected by immunoblotting methods, including nitric oxide synthase (iNOS), cyclooxygenase (COX) 1, COX 2, inflammatory cytokines [interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α)], and inflammatory-related signaling proteins [Akt, extracellular signal-regulated kinase 5 (ERK5), IκB, and NFκB]. We found that chrysin (1) and 4′-methoxytricetin (9) had relatively strong anti-inflammatory activity and low cytotoxicity Moreover, 1 and 9 recovered the expression levels of iNOS and COX2, as well as those of the intracellular inflammatory mediators IL-1β and IL-6, which were up- regulated by LPS stimulation. In addition, 1 and 9 actively regulated the phosphorylation of IκBα, leading to activation of NFκB. Under LPS stimulation, phosphorylation of Akt and ERK5 (upstream of NFκB) was strongly regulated by 1 and 9, as well as by BIX 02189 and LY 294002, which are phosphorylation inhibitors of ERK5 and Akt, respectively. The results suggest that compounds 1 and 9 may suppress iNOS and COX2 levels by regulating phosphorylation of Akt, ERK5, and IκB, and thus regulating NFκB-related signaling pathways, resulting in anti-inflammatory effects. Because 1 and 9 had low cytotoxicity and regulated both PGE2 and NO production, they may hold promise as natural anti-inflammatory agents.

    Zoom Image
    Fig. 1: Chemical structures of 5, 7-dihydroxyflavone analogs

    Acknowledgements: This work was supported by funding from Nihon University College of Science and Technology Project Research and from Nihon University Academic Study.

    Keywords: 5, 7-dihydroxyflavone, inflammatory, RAW264.7 cells, Akt, ERK5, IκBα, NFκB.

    Reference:

    [1] Nishina A, Ukiya M, Fukatsu M, Koketsu M, Ninomiya M, Sato D, Yamamoto J, Kobayashi-Hattori K, Okubo T, Tokuoka H, Kimura H. Effects of various 5,7-dihydroxyflavone analogs on adipogenesis in 3T3-L1 cells. Biol Pharm Bull 2015; 38: 1794 – 1800


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    No conflict of interest has been declared by the author(s).

     
    Zoom Image
    Fig. 1: Chemical structures of 5, 7-dihydroxyflavone analogs