Pinoresinol from the fruits of Forsythia koreana inhibits inflammatory responses in LPS-activated microglia.

Abstract The activation of microglia plays an important role in a variety of brain disorders by the excessive production of inflammatory mediators such as nitric oxide (NO), prostaglandin E 2 (PGE 2 ) and proinflammatory cytokines. We investigated here whether pinoresinol isolated from the fruits of Forsythia koreana Nakai inhibits the inflammatory responses in LPS-activated microglia. Pinoresinol inhibited the production of NO, PGE 2 , TNF-α, IL-1β and IL-6 in LPS-activated primary microglia. Also, pinoresinol attenuated mRNA and protein levels of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2) and proinflammatory cytokines in LPS-activation. However, most of these inhibitory effects of pinoresinol have been mediated by extracellular-signal-regulated kinase (ERK) 1/2 mitogen-activated protein kinase (MAPK) phosphorylation and the NF-κB dependent. The results suggest that pinoresinol attenuates inflammatory responses of microglia and could be potentially useful in modulation of inflammatory status in brain disorders.