Iridis tectori Rhizome Alleviates LPS-Triggered Inflammatory Responses Through Inhibiting NF-κB Signaling in Macrophages.

Objectives: The rhizome of Iris tectorum Maxim. (Chuan She Gan), commonly used as a substitute for She Gan in Sichuan and other regions, is traditionally applied for inflammation-related disorders. This study aimed to evaluate the anti-inflammatory activity of Chuan She Gan ethanolic extract (CSG) and elucidate its molecular mechanism. Methods: CSG was prepared by 85% ethanol extraction and analyzed by HPLC to identify representative constituents. In LPS-stimulated RAW264.7 macrophages, nitrite accumulation and iNOS activity, cytokine production and inflammatory gene expression were evaluated using Griess assays, ELISA, and qRT-PCR, respectively. NF-κB and AP-1/MAPK signaling were determined using luciferase reporter assays and Wwestern blotting. Serum inflammatory cytokine levels of endotoxemic mice were measured by ELISA. Results: Four characteristic isoflavones/glycosides in CSG were identified, including tectoridin, iridin, tectorigenin, and irigenin. In LPS-activated RAW264.7 macrophages, CSG not only dose-dependently suppressed supernatant NO by inhibiting iNOS activity and downregulating iNOS expression, but also reduced IL-6, MCP-1, and intracellular pro-IL-1β at the protein and mRNA levels. Mechanistic analyses indicated that CSG attenuated NF-κB activation by reducing IκBα phosphorylation and limiting p65 nuclear accumulation, while AP-1/MAPK signaling remained largely unchanged. In endotoxemic mice, a single oral gavage of CSG (50-200 mg/kg) significantly lowered serum IL-6, MCP-1, and TNF-α levels. Conclusions: CSG showed anti-inflammatory activity in LPS-stimulated macrophages and endotoxemic mice. In LPS-stimulated macrophages, CSG suppressed inflammatory mediator production primarily through the inhibition of NF-κB signaling. In endotoxemic mice, CSG reduced the serum levels of pro-inflammatory cytokines. These findings provide pharmacological basis for the traditional use of Chuan She Gan.