Anti-Inflammatory Effect of Pestalotic Acid A Derived from an Endophytic Fungus of , in Lipopolysaccharide-Stimulated RAW264.7 Cells.

Pestalotic acid A (PAA), a polyketide derived from , an endophyte of the Japanese holly (), is known to exhibit known antimicrobial activity, but its anti-inflammatory properties remain uncharacterized. This study aimed to investigate the anti-inflammatory effects of PAA in lipopolysaccharide (LPS)-stimulated murine macrophages, RAW264.7 cells. PAA was isolated from endophytes of and its structure was confirmed. RAW264.7 macrophages were treated with 0-50 μM of PAA in the presence of 100 ng/mL LPS. Cell viability was assessed by MTS assay; nitric oxide (NO) production was measured via Griess reagent; interleukin (IL)-6, IL-1β, and tumor necrosis factor (TNF) were quantified by enzyme-linked immunosorbent assay. Protein expression of inducible NO synthase (iNOS), nuclear factor (NF)-κB p65 phosphorylation, and related signaling proteins was evaluated by Western blot analysis and immunofluorescence staining. PAA significantly increased macrophage viability and dose-dependently inhibited the release of NO by alleviating the protein expression of iNOS in LPS-treated RAW264.7 cells. Furthermore, PAA suppressed the release of IL-6, IL-1β, and TNF induced by LPS. Western blot and immunofluorescence results also indicated that PAA blocked the p65 subunit phosphorylation of NF-κB, which is one of the underlying mechanisms of the anti-inflammatory action of pestalotic acid A. PAA exerts potent anti-inflammatory effects in LPS-stimulated macrophages via inhibition of the NF-κB pathway, highlighting its potential as a natural therapeutic agent for inflammatory diseases.