Linarin Inhibits Mast Cell Degranulation and Ameliorates AllergicRhinitis in Rats by Suppressing ERK/p38 MAPK Signaling Pathway

INTRODUCTION: Linarin, a flavonoid abundant in medicinal plants such as Chrysanthemum indicum, has been reported to possess anti-inflammatory properties, yet its anti-allergic potential remains unclear. To evaluate the anti-allergic effects of linarin and investigate its underlying mechanisms using in vitro and in vivo models. METHODS: An in-vitro model of mast-cell activation was created by stimulating RBL-2H3 cells with compound 48/80. Degranulation was quantified by β-hexosaminidase (β-Hex) release, and the expression levels of MAPK pathway proteins were analysed using Western blotting. An ovalbumin-induced allergic rhinitis model was estalished in rats, chlorpheniramine was used as the positive control. Serum IgE, IL-4 and TNF-α levels were measured, nasal-mucosa histopathology was examined. Safety evaluations included body weight, serum biochemistry and histology of the heart, liver and kidneys. RESULTS: Linarin inhibited C48/80-induced degranulation in a dose-dependent manner, reducing β-Hex release (P < 0.05) and suppressing ERK1/2 and p38 MAPK phosphorylation. In rats, all linarin doses lowered serum IgE, IL-4 and TNF-α levels (P < 0.05), alleviating pathological damages of the nasal mucosa, including congestion, oedema, and inflammatory-cell infiltration. Spleen index showed normalisation after linarin treatment, indicating improved immune function. No adverse effects on body weight, blood chemistry or major organ histology were detected, demostrating a favrouable safety profile. DISCUSSION: Linarin showed anti-allergnic effect by regulating mast-cell degranulation and pro-flammatory cytokine release via MAPK signaling pathway inhibition, without adverse effects. CONCLUSION: These findings support linarin as a promising safe, natural anti-allergic agent.