Harpagophytum procumbens (Devil's Claw): A Possible Natural Anti-Inflammatory Agent (An Experimental Study)

Extract of Harpagophytum procumbens (devil's claw) has become the focus of research as a potential therapeutic agent in the treatment of rheumatic arthritis and pain due to its favorable side effects profile compared to synthetic alternatives. This superior safety of treatment is very valuable, especially in view of that in mandatory long duration of therapy in chronic diseases. None of NSAIDs is ideal in controlling or modifying the signs and symptoms of inflammation, particularly in the common inflammatory joint diseases. Many studies evaluated the anti-inflammatory and analgesic effects of Harpagophytum procumbens with inconsistent and contradictory results. The aim of this study was to investigate the effect of Harpagophytum procumbens on both acute and chronic inflammatory processes in rats and pain responses in mice. In addition, its safety on gastric and duodenal mucosa was evaluated histopathologically. Eighty rats of both sexes weighing 150-200 g each and twenty-four mice of both sexes weighing 25-30 grams each, were used in this work. For a pharmacological study, these animals were classified for induction of the different experimental models. The acute model of inflammation includes Carrageenan-induced rat back-paw edema test. The chronic models of inflammation include Complete Freund's adjuvant-induced arthritis test and cotton pellet-induced granuloma test. The analgesic model includes writhing test in mice. A biochemical study was done on the Complete Freund's adjuvant-induced arthritis test group. Blood samples were taken for measuring acute phase proteins; C-reactive protein and serum albumin, and serum cortisol. Histopathological assessment of gastric and duodenal mucosa for the effect of Harpagophytum procumbens in comparison with the effect of indomethacin was done in the Complete Freund's adjuvant-induced arthritis test group. In Carrageenan-induced rat back-paw edema test; Carrageenan sub-plantar injection in right back-paw in rats induced highly significant increase in paw thickness (p = 0.001). Harpagophytum procumbens pre-treatment induced highly significant reduction (p = 0.001) in right back-paw thickness, an effect similar to indomethacin. In Complete Freund's adjuvant-induced arthritis test; Freund`s adjuvant-induced arthritis in rats induced highly significant increase in paw thickness of rats (p = 0.001), significant decrease in serum cortisol (p = 0.05), highly significant decrease in serum albumin (p = 0.001) and significant increase in C-reactive protein (p = 0.05). Harpagophytum procumbens and indomethacin administration caused insignificant effects on these parameters and caused only significant reduction of paw thickness (p = 0.05). In cotton pellet-induced, granuloma test; Harpagophytum procumbens and indomethacin intra-peritoneal administration in cotton pellet-induced granuloma in rats caused a reduction of inflammation manifested by marked and highly significant decrease of cotton pellet weight (p = 0.001). In Writhing test in mice, Harpagophytum procumbens and acetyl salicylic acid had an analgesic effect manifested by highly significant reduction in the number of writhing reactions (p = 0.001). The results of the histopathological study revealed the greater safety of Harpagophytum procum-bens on GIT mucosa in comparison to the more injurious effect of indomethacin as a NSAID.