3,4,5-Trihydroxycinnamic Acid Inhibits LPS-Induced iNOS Expression by Suppressing NF-κB Activation in BV2 Microglial Cells

Although various derivatives of caffeic acid have been reported to possess a wide variety of biological activities such as neuronal protection against excitotoxicity and anti-inflammatory property, the biological activity of 3,4,5-trihydroxycinnamic acid (THC), a derivative of hydroxycinnamic acids, has not been clearly examined. The objective of the present study is to evaluate the anti-inflammatory effects of THC on lipopolysaccharide (LPS)-stimulated BV2 microglial cells. THC significantly suppressed LPS-induced excessive production of nitric oxide (NO) and expression of iNOS, which is responsible for the production of iNOS. THC also suppressed LPS-induced overproduction of pro-inflammatory cytokines such as IL-1β and TNF-α in BV2 microgilal cells. Furthermore, THC significantly suppressed LPS-induced degradation of IκB, which retains NF-κB in the cytoplasm. Therefore, THC attenuated nuclear translocation of NF-κB, a major pro-inflammatory transcription factor. Taken together, the present study for the first time demonstrates that THC exhibits anti-inflammatory activity through the suppression of NF-κB transcriptional activation in LPS-stimulated BV2 microglial cells.