Chemical structure and pharmacological (curarizing) properties of various indole alkaloids extracted from an African Strychnos.

The chemical separation and identification of ten alkaloids extracted from the roots of Strychnos usambarensis are described. The elucidation of their structure by means of elementary analysis, I. R., U.V, and mass spectrometry allows their classification into bistertiary amines, hybrid and bisquaternary ammonium derivatives. This classification is reflected in the pharmacological properties. One of the tertiary amine alkaloids (usambarensine) presents atopine-like and spasmolytic activities while the bisquaternary ammonium compounds (dihydrotoxiferine, calebassine, C-curarine and afrocurarine) are competitive neuromuscular blocking agents.