Haginin A suppresses oxidative stress and pro-inflammatory mediators via MAPK and inflammasome regulation in LPS-stimulated microglia.

Haginin A (HA), a flavonoid isolated from Lespedeza cyrtobotrya, has been reported to possess various biological activities; however, its anti-neuroinflammatory activity has not been clarified yet. In this study, we investigated the effect of HA on lipopolysaccharide (LPS)-induced inflammatory response in microglia. HA treatment significantly reduced nitric oxide (NO), and inflammation-inducing cytokines including tumor necrosis factor (TNF)-α and interleukin (IL)-6, in LPS-stimulated BV2 microglial cells. HA also decreased the mRNA expression of inflammatory mediators, including inducible nitric oxide synthase (iNOS), IL-1β, IL-6, and TNF-α. Western blot analysis revealed that HA inhibited iNOS protein expression without significantly affecting cyclooxygenase-2 (COX-2) protein levels, whereas enzymatic and molecular docking analyses suggested a potential inhibitory effect on COX-2 activity. Furthermore, HA significantly inhibited the activation of key mitogen-activated protein kinase (MAPK) signaling pathways and inhibited nucleotide-binding oligomerization domain-like receptor family pyrin domain containing 3 (NLRP3) inflammasome activation, thereby reducing pro-IL-1β cleavage and mature IL-1β levels. Notably, HA strongly attenuated LPS-induced reactive oxygen species (ROS) production in both mouse BV2 and human HMC3 microglia. Collectively, these findings suggest that HA attenuates inflammatory and oxidative responses in LPS-stimulated microglia and may have potential as a modulator of neuroinflammatory processes.