Inhibitory Effect of Litchi (Litchi chinensis Sonn.) Flower on Lipopolysaccharide-Induced Expression of Proinflammatory Mediators in RAW264.7 Cells through NF-κB, ERK, and JAK2/STAT3 Inactivation

Litchi (Litchi chinensis Sonn.) flower ethanolic extract (LFEE) was found to contain five flavanoids [total amount, 102.73 +/- 5.50 mg/g of dried extract (gDE)], nine phenolic acids (total amount, 60.31 +/- 4.52 mg/gDE), and proanthocyanidin A2 (79.31 +/- 2.95 mg/gDE). LFEE was used to evaluate the inhibitory effects on lipopolysaccharide- (LPS-) induced pro. inflammatory mediators in RAW264.7 cells. The results showed that LFEE treatment could suppress the expressions of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), the productions of nitric oxide (NO) and prostaglandin E2 (PGE2), and the secretions of pro-inflammatory cytokines [interleukin-1 beta (IL-1 beta), IL-6, and tumor necrosis factor alpha (TNF-alpha)] in the LPS-mediated RAW264.7 cells. The attenuation of LPS-induced inflammatory responses by LFEE was found to be closely related to the inhibition of the translocation of nuclear factor kappa B (NF-kappa B) p50/p65 subunits correlated with suppression of the activation of the inhibitor of kappa B kinase (IKK) alpha/beta and downregulation of activation of extracellular signal-regulated kinase (ERK) and Janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3).