Isolation and Spasmolytic Evaluation of New Alkaloids from Dichrostachys cinerea (L.) Wight et Arn. (Fabaceae)

Dichrostachys cinerea (L.) Wight et Arn. (Fabaceae) root bark is used in Ivorian Traditional Medicine to treat asthma, which is a respiratory disorder characterized by inflammation and the restriction of tracheal muscles obstructing the air circulation. The tracheal relaxant effect of a crude aqueous-alcoholic extract of the plant root bark was previously shown. For the present study, alkaloids were isolated from the same extract and investigated ex vivo in C57Bl/6j mice isolated trachea contracted with carbachol 1 μM, in comparison with a reference bronchodilatator, i.e. salbutamol. Two extraction procedures allowed isolating 2 Alkaloids that monodimensional and bi-dimensional nuclear magnetic resonance (NMR) and mass specters allowed identifying a pyrolidine structure type nucleus with a long bi-hydroxyled alkyl chain. Alkaloid 1, carrier of a sugar, is a glycoside of Alkaloid 2. Both alkaloids induced similar spasmolytic effects, but Alkaloid 1 was more effective than Alkaloid 2 at 9 × 10-6 M (p ＜ 0.01), 3 × 10-5 M, and 9 × 10-5 M (p ＜0.001). Salbutamol induced its spasmolytic effect in a different way, and its maximal effect Emax (less than 30%) was obtained at 9 × 10-6 M, while Emax of both alkaloids (100%) was obtained at 3 × 10-4 M.