Anti-inflammatory and anti-arthritic properties of aqueous extract of Nauclea diderrichii (Rubiaceae) stem bark in rats

Nauclea diderrichii , is a common woody plant in Africa where it is traditionally used for the relief and treatment of multiple pain-related conditions. The aim was to evaluate the inflammatory and anti-arthritic properties of the aqueous extract of N. diderrichii stem bark. Carrageenan and formalin were used to induce inflammation while zymosan A was used to induce monoarthritis in rats. The extract was given orally at doses of 100, 200 and 400 mg/kg. The extract significantly reduced carrageenan-induced edema up to 6 h, with 61.94% (6th hour). The extract induces a significant inhibition of the formalin-induced edema from the 2nd to the 8th hour with 61.50% (2nd hour). In continuous treatment, the activity of the extract remains significant from the 2nd to the 10th day of treatment with 63.85% (9th day). The extract (400 mg/kg) induces a significant decrease of the organ weight while the body weight increases significantly. At 400 mg/kg, the extract significantly increases the levels of red blood cells, hemoglobin and proteins, as well as the catalase and SOD activities, then a significant decrease of the levels of white blood cells, lymphocytes, hematocrit, MDA and NO. Furthermore, the extract significantly inhibited zymosan A-induced edema from the 1st to the 5th day with 60.99% (5th day). The joints of the treated animals show a close to normal architecture compared to that of the untreated animals. These results demonstrate the anti-inflammatory and anti-arthritic properties of N. diderrichii and confirm its traditional use to relieve pain and inflammation.