The Ethanolic Extract of Eysenhardtia polystachya (Ort.) Sarg. Bark and Its Fractions Delay the Progression of Rheumatoid Arthritis and Show Antinociceptive Activity in Murine Models

Eysenhardtia polystachya is widely used in folk medicine as an anti-rheumatic and analgesicagent, but no systematic study of its effects on several markers associated with rheumatoidarthritis and its ethnomedical use as analgesic agent has been performed. We evaluated theanti-arthritic and antinociceptive properties of an ethanolic extract of E. polystachya (EE) barkand its rich-flavonoids fractions in murine models. The EE was administered orally at doses of25, 50, 100, and 200 mg/kg/day, and its fractions at 25 mg/kg/day in all animal models. Antiarthriticactivity was evaluated using a complete Freund´s adjuvant (CFA)-induced rheumatoidarthritis model in rats. The severity of arthritis was evaluated by changes in paw oedema,body weight, arthritic index, radiological scores, histological assessment of synovial joints,erythrocyte sedimentation rate, haematocrit, haemoglobin, serum rheumatoid factor, serumC-reactive protein and serum levels of the pro-inflammatory cytokines IL-1β, IL-6, TNF-α,IL-18, IFN-γ, GM-CSF, and anti-inflammatory cytokines IL-4, IL-10, IL-13. Antinociceptiveactivity was evaluated using an acetic acid-induced abdominal contraction test and a hot-platetest in mice. EE and its rich-flavonoids fractions inhibited secondary inflammatory reactions,diminished the specific histopathological alterations in the joint capsule and reduced the serumconcentrations of the pro-inflammatory cytokines IL-6, TNF-α, and GM-CSF in arthritic rats.EE also reduced the number of writhes produced by acetic acid and increased the response timeon the hot plate for mice. Our findings support the use of Eysenhardtia polystachya bark for thetreatment of rheumatoid arthritis and pain management.