Objective: To evaluate spasmolytic mechanisms of aqueous and methanolic extracts from Distemonanthus benthamianus trunk-bark. Methods: Spasmolytic activities of extracts were evaluated in vitro on spontaneous and potassium chloride-induced jejunum contractions, or against cholinergic [acetylcholine (0.3μmol/L)] stimulations. High performance liquid chromatography analysis of both extracts was performed in reference to standard compounds. Results: Extracts developed concentration-dependent inhibitory activities. The methanolic extract, which revealed better activity, produced spasmolytic and myorelaxant effects at concentrations of 0.01-0.30 mg/mL with EC50 of 0.06 and 0.09 mg/mL (95％ CI: 0.03-0.3 mg/mL), respectively. Its anticholinergic effect was obtained at the same concentrations with EC50 of 0.11 mg/mL (95％ CI:0.03-0.3 mg/mL). Chromatograms showed the presence of gallic acid in both extracts, rutin being only detected in the aqueous extract. Conclusions: Distemonanthus benthamianus extracts exhibit verapamil and atropine-like activities, thus highlighting calcium channels and muscarinic receptors blocking potentials, which may be conveyed by some phenolic compounds. These results confirm the antidiarrheal activity of Distemonanthus benthamianus extracts.

Objective: To evaluate the anti-arthritic effect of aqueous and methanolic extracts of Distemonanthus benthamianus. Methods: Monoarthritis was induced by an injection of 0.3 mL zymosan A (0.9% NaCl, v/v) in the right posterior knee joints of rats. Then, joint diameter and pain threshold were determined. Polyarthritis was induced by an intracaudal injection of complete Freund’s adjuvant and rats were treated from day 14 post 1st complete Freund’s adjuvant injection until 28 day. The clinical, hematological, biochemical and oxidative stress parameters were evaluated. In addition, histological analysis of the knee joint was perfomed in both tests. Results: The aqueous and methanolic extracts of Distemonanthus benthamianus at a dose of 500 mg/kg ameliorated zymosan A-induced monoarthritis, as evidenced by reduced joint diameter, increased pain threshold, as well as improved joint architecture. In addition, both extracts of Distemonanthus benthamianus markedly increased body weight and pain threshold, while reducing paw edema in polyarthritic rats. They also led to a marked decrease in platelets and white blood cells (P<0.05), as well as a significant increase in red blood cells, hemoglobin and hematocrit (P<0.05). The aqueous and methanolic extracts of Distemonanthus benthamianus significantly reduced alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase activities, while increasing serum protein levels (P<0.05) with no significant variation in creatinine level. Moreover, both extracts increased catalase and glutathione activities (P<0.05), and inhibited malondialdehyde and nitric oxide production (P<0.01 and P<0.001) in the liver and kidneys. Histological analysis of the joints showed that both extracts triggered tissue reparation. Conclusions: Distemonanthus benthamianus could be used as a potential candidate in the treatment of rheumatoid arthritis.