Anti-inflammatory activity of <i>Staphylea bumalda</i> leaves through inhibiting ERK1/2 and NF-κB signalling, and activating Nrf2/HO-1 signalling in LPS-stimulated RAW264.7 cells

Staphylea bumalda leaves (SBL) are known to possess anti-inflammatory properties. However, there is a lack of clear study on the mechanisms underlying its anti-inflammatory activity. Therefore, this study aims to elucidate the mechanisms related to the anti-inflammatory effects of SBL. SBL70E effectively inhibited the production of NO, iNOS, COX-2, IL-1β, and IL-6 induced by LPS in RAW264.7 cells. SBL70E inhibited the phosphorylation of ERK1/2 and p65 in LPS-stimulated RAW264.7 cells. In addition, SBL70E suppressed LPS-mediated activation of NF-κB luciferase activity. SBL70E increased the levels of HO-1 and nuclear Nrf2. However, inhibition of p38, JNK and PI3K blocked SBL70E-mediated increase in HO-1 and nuclear Nrf2. These findings suggest that SBL70E suppresses the production of inflammatory mediators caused by LPS in RAW264.7 cells through the inhibition of ERK1/2 and NF-κB signalling and activation Nrf2/HO-1 signalling via the activation of p38, JNK, and PI3K. These findings imply that SBL70E exhibits anti-inflammatory activity.