Endotoxin (lipopolysaccharide)-induced inflammation in albino rat and macrophages (RAW 264.7): Piper mullesua leaf extract as promising therapeutic against inflammatory pathophysiology via SOCS1 activation and phospho-NF-κB/JAK1/STAT1 inhibition.

The present investigation has been attempted for scientifically validating the traditional uses of Piper mullesua against inflammatory pathophysiology using both in vivo (albino rats) and in vitro (macrophage cells, RAW 264.7) models of inflammation caused by an endotoxin (lipopolysaccharide, LPS). Oral gavaging with PMHAE, hydroalcoholic extract of Piper mullesua leaves, dose-responsively (50, 100, or 200 mg/kg BW, 14 days) restored any alteration in the concentration of serum inflammatory cytokines, IL-6, TNF-α, IL-4, and IL-10 and decreased prostaglandin (PGE2) and nitrite count in rats injected (i.p.) with LPS (10 mg/kg BW). PMHAE supplementation (5, 10, or 20 µg/mL) further attenuated MCP-1, IL-6, and TNF-α, and increased IL-10 and IL-4 secretion and mRNA expression in LPS-treated (50 ng/mL) macrophages. PMHAE also enhanced phagocytic potential while attenuated ROS counts in LPS-treated cells. Additionally, PMHAE supplementation increased SOCS1 protein expression and decreased NF-κB phosphorylation (Serine 536), along with the expression of JAK1/STAT1 proteins in LPS-treated cells. Treatment with PMHAE did not cause any toxicity to animals and cultured cells. Phytochemical analysis (LC-MS/GC-MS) revealed various compounds, including piperine, piperlongumine, pipernonaline, phytol, methyl eugenol, and pinene, contributing to anti-inflammatory potential of PMHAE. These findings suggested Piper mullesua as a safe, effective, and potential anti-inflammatory avenue for therapeutic exploration in inflammatory pathophysiology.