Immunomodulatory and Antioxidant Potencies of γ‐irradiated Piper cubeba in Complete Freund's Adjuvant‐Induced Arthritis in Rats

Piper cubeba (P. cubeba), renowned for its antioxidant properties, has traditionally been used to counteract pro-oxidant effects caused by toxicants. This study investigated the potential immunomodulatory and antioxidant activities of γ-irradiated P. cubeba in a model of rheumatoid arthritis (RA) induced by complete Freund's adjuvant (CFA) in female Wistar rats. RA was induced by a single subcutaneous injection of 0.1 mL of CFA into the right hind footpad. For 3 weeks, arthritic rats received an oral dose of methanolic extract of γ-irradiated P. cubeba (50 mg/kg body weight/day). Blood and tissue samples were measured for MMP-1, MMP-3, ACCP, TNF-α, IL-17, IL-10, and NQO1 levels using ELISA, as well as for the oxidative stress marker MDA and the antioxidant enzyme SOD. CFA-induced RA resulted in marked increases in the expression of cyclooxygenase-2 (COX-2), tumor necrosis factor-alpha, oxidative stress markers, and matrix metalloproteinases. Meanwhile, treatment with irradiated P. cubeba reduced the severity of these changes by increasing anti-inflammatory cytokine IL-10 and enhancing FOXP3 expression, a key regulator of T regulatory (Treg) cells, in arthritic rats. These findings demonstrate that irradiated P. cubeba exerts immunomodulatory, antioxidant, and anti-inflammatory effects.