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Evidence-Based Complementary and Alternative Medicine
Volume 2013, Article ID 127672, 11 pages
Research Article

Molecular Mechanisms Underlying the In Vitro Anti-Inflammatory Effects of a Flavonoid-Rich Ethanol Extract from Chinese Propolis (Poplar Type)

1College of Animal Sciences, Zhejiang University, Hangzhou 310058, China
2Life Sciences Institute, Zhejiang University, Hangzhou 310058, China
3School of Life Science, Liaocheng University, Liaocheng 252059, China

Received 19 November 2012; Revised 18 December 2012; Accepted 18 December 2012

Academic Editor: José Maurício Sforcin

Copyright © 2013 Kai Wang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


China produces the greatest amount of propolis but there is still lack of basic studies on its pharmacological mechanisms. Our previous study found that ethanol extract from Chinese propolis (EECP) exerted excellent anti-inflammatory effects in vivo but mechanisms of action were elusive. To further clarify the possible mechanisms underlying the anti-inflammatory effects of Chinese propolis (poplar type), we utilized EECP to analyze its chemical composition and evaluated its potential anti-inflammatory effects in vitro. High-performance liquid chromatography (HPLC) profile indicated that EECP contained abundant flavonoids, including rutin, myricetin, quercetin, kaempferol, apigenin, pinocembrin, chrysin, and galangin. Next we found that EECP could significantly inhibit the production of NO, IL-1β, and IL-6 in lipopolysaccharide- (LPS-) stimulated RAW 264.7 cells and suppress mRNA expression of iNOS, IL-1β, and IL-6 in a time- and dose-dependent manner. Furthermore, we found that EECP could suppress the phosphorylation of IκBα and AP-1 but did not affect IκBα’s degradation. In addition, using a reporter assay, we found that EECP could block the activation of NF-κB in TNF-α-stimulated HEK 293T cells. Our findings give new insights for understanding the mechanisms involved in the anti-inflammatory effects by Chinese propolis and provide additional references for using propolis in alternative and complementary therapies.