Anti-inflammatory Activity and Mechanism of Total Flavonoids from the Phloem of Paulownia elongate S.Y. Hu in LPS-stimulated RAW264.7 Macrophages

The juice leaked from broken phloem of Paulownia elongate S.Y.Hu has been used to cure acute inflammation resulted from stung injury by poisonous insects for a long time in China,but its potential mechanism remains unclear.The present study was designed to evaluate anti-inflammatory activity and mechanism of total flavonoids from the phloem of P.elongate S.Y.Hu in RAW264.7 cells.Lipopolysaccharide(LPS)-induced nitric oxide(NO)was measured by Griess and mRNA of pro-inflammatory mediators was analyzed by q-PCR.Cell viability was measured using cell counting kit(CCK)-8 assay.The protein level was analyzed by Western blot.The results showed that the total flavonoids of P.elongate significantly inhibited the production of the pro-inflammatory mediators such as NO,interleukin(IL)-1β and interleukin(IL)-6 in LPS-stimulated RAW264.7 cells.Total flavonoids of P.elongate exerted potential anti-inflammatory activity through the regulation of several signaling pathways.Total flavonoids of P.elongate inhibited JAK/STAT by blocking JAK2 and STAT3 phosphorylation levels.This is the first report on anti-inflammatory activity of total flavonoids from the phloem of P.elongate,which suggests that the total flavonoids of P.elongate may have great potential for the development of anti-inflammatory drug to treat inflammatory disorders.