Assessment of anti-arthritic potential of pulegone in formaldehyde- and Complete Freund’s Adjuvant-induced arthritis in rats

Pulegone, a monoterpene phytochemical, was evaluated for its anti-inflammatory and anti-arthritic properties. This study investigated its preventive efficacy against rheumatoid arthritis using in vivo animal models and in vitro assays. The in vitro analysis included the inhibition of egg albumin and bovine serum albumin (BSA) denaturation, as well as the stabilization of red blood cell membranes against hemolysis, across concentrations of 50–6400 μg/mL. For in vivo evaluation, arthritis was induced using formaldehyde and Complete Freund’s Adjuvant (CFA) models, with pulegone administered at doses of 20, 40, and 80 mg/kg. The mRNA expression levels of key inflammatory mediators, including interleukin-1 beta (IL-1β), interleukin-17 (IL-17), nuclear factor-kappa B (NF-κB), tumor necrosis factor-alpha (TNF-α), interleukin receptor-associated kinase (IRAK), and interleukin (IL)-10 and IL-17, were also analyzed. Results showed concentration-dependent inhibition of egg albumin and BSA denaturation, with maximum erythrocyte membrane-stabilizing effects observed at 6400 μg/mL. Pulegone exhibited dose-dependent anti-arthritic activity in the formaldehyde model, with the highest efficacy at 80 mg/kg. In the CFA model, pulegone significantly reduced arthritic lesions, mitigated weight loss, reversed hematological and biochemical abnormalities, and improved radiographic and histopathological outcomes. Additionally, pulegone demonstrated potent antioxidant effects in superoxide dismutase and reducing power assays. Treatment with pulegone significantly reduced pro-inflammatory cytokines (IL-1β, TNF-α, IRAK, and NF-κB) while increasing anti-inflammatory cytokines (IL-10 and IL-17) compared to the control group. In conclusion, pulegone effectively suppressed inflammatory responses in rheumatoid arthritis by modulating cytokine levels and enhancing antioxidant activity, making it a promising candidate for therapeutic development.