Ameliorative Effect of Morin, a Plant Flavonoid against Freund’s Complete Adjuvant‑Induced Polyarthritis in Rats

Objective: The aim is to study the anti‑arthritic activity of the morin against adjuvant‑induced polyarthritis in rats. Materials and Methods: Polyarthritis was induced in female Wistar rats (150–180 g) using Freund’s complete adjuvant (FCA) in the tail. Leflunomide (10 mg/kg, as a standard) and morin (10, 30 and 100 mg/ kg) were administered orally daily for 28 days. Results: Treatment with morin (30 and 100 mg/kg) showed statistically significant inhibition (P < 0.05) in FCA‑induced decrease in thermal hyperalgesia and mechanical hyperalgesia. It also showed significant attenuation (P < 0.05) in FCA‑induced alterations in hematological parameters, aspartate aminotransferase, alanine transaminase, alkaline phosphatase, serum turbidity, albumin, C‑reactive protein, blood sugar levels, and erythrocyte sedimentation rate. Altered levels of serum and liver lipid profile were significantly attenuated (P < 0.05) by morin (30 and 100 mg/kg). Morin treatment significantly decreased (P < 0.05) serum oxido‑nitrosative stress, tumor necrosis factor‑alpha (TNF‑α), and interleukin‑1β (IL‑1β) levels. Morin (30 and 100 mg/kg) also significantly (P < 0.05) inhibited FCA‑induced up‑regulated liver TNF‑α, IL‑1β, IL‑6, heme oxygenase‑1, transforming growth factor‑beta and down‑regulated nuclear factor erythroid 2‑related factor‑2 messenger RNA expression. Histopathology alteration‑induced by FCA was also reduced by morin treatment. Conclusion: Morin showed promising curative properties against FCA‑induced polyarthritis in rats via modulation of endogenous biomarkers. Thus, morin can be considered as an alternative treatment regimen for the management of arthritis.