Anti-inflammatory mechanism of Achyranthes longifolia extract and its component chikusetsusaponin IVa by modulating Nrf2/NF-κB pathways in vitro and in vivo

This study aims to explore the anti-pharyngitis mechanisms of Achyranthes longifolia (Makino) Makino. extract (ALE) and the anti-inflammatory mechanisms of its major bioactive component, chikusetsusaponin IVa (CIVa). To this end, the present study established an ammonia-induced acute pharyngitis rat model to assess the therapeutic efficacy of ALE and a lipopolysaccharide (LPS)-induced RAW264.7 cells model to evaluate the anti-inflammatory and antioxidant properties of CIVa. Pharyngeal severity was evaluated using appearance index and HE staining, while ELISA was employed to quantify inflammatory cytokines TNF-α, PGE2, and IL-6. Additionally, the levels of SOD, CAT, and MDA were measured to assess antioxidant status. Western blot was conducted to analyze the expression of proteins associated with the Nrf2/NF-κB pathways. The findings indicate that ALE provides protection in the ammonia-induced acute pharyngitis rat model, as evidenced by reduced pharyngeal redness, swelling, and improved histopathological changes. CIVa, the primary constituent of ALE, demonstrates anti-inflammatory effects in LPS-induced RAW 264.7 cells by inhibiting NO production and reducing the levels of inflammatory cytokines in a dose-dependent manner. The underlying mechanism appears to involve the inhibition of the NF-κB pathway, activation of the Nrf2 pathway, modulation of oxidative stress, and reduction of pro-inflammatory cytokine release. These results position ALE and CIVa as promising alternative therapeutic agents for the management of acute pharyngitis and potentially other inflammatory disorders.