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

Abstract

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 E max (less than 30%) was obtained at 9 × 10 −6 M, while E max of both alkaloids (100%) was obtained at 3 × 10 −4 M.