Anti-Inflammatory Effects of Stachys pilifera Extracts in LPS-Stimulated RAW264.7 Macrophages

Inflammation is a fundamental biological response that serves to protect the body from physical damage and harmful stimuli. However, chronic inflammation is implicated in the pathogenesis of various inflammatory diseases. Stachys pilifera Benth. has been traditionally used for its anti-inflammatory properties, yet its precise mechanisms of action remain to be fully elucidated. This study aims to investigate the effects of S. pilifera Benth. extract and its fractions on lipopolysaccharide (LPS)-induced inflammatory responses in RAW264.7 macrophage cells.

The anti-inflammatory potential of the methanolic extract and its ethyl acetate, butanol, and water fractions were evaluated by assessing their inhibitory effects on nitric oxide (NO) and prostaglandin E2 (PGE₂) production. Additionally, nuclear factor-κB (NF-κB) concentration and cyclooxygenase-2 (COX-2) gene expression were analyzed in LPS-stimulated macrophage cells.

The methanolic extract, ethyl acetate fraction, and butanol fraction significantly reduced the production of NO and PGE₂, decreased NF-κB concentration, and suppressed COX-2 mRNA expression in a dose-dependent manner. The butanol fraction exhibited the most potent inhibition of NO production (IC₅₀ = 37.38 ± 10.27 µg/mL), whereas the ethyl acetate fraction was the strongest suppression of PGE₂ synthesis (IC₅₀ = 86.32 ± 5.51 µg/mL). In contrast, the water fraction did not have a significant effect on these inflammatory markers.

By downregulating NF-κB activity, S. pilifera Benth. effectively modulates the expression of key proinflammatory mediators, including inducible NO synthase (iNOS) and COX-2, ultimately leading to reduced NO and PGE₂ production. These findings suggest that S. pilifera Benth. may exert its anti-inflammatory effects through inhibition of the NF-κB signaling pathway, offering potential therapeutic applications in the management of chronic inflammatory diseases.