Five new alkaloids have been isolated from the leaves and stems of Strychnos henningsii: tsilanimbine, Na-desacetyl-17-O-acetyl-18-hydroxyisoretuline, 18-hydroxyisoretuline, Na-desacetylisoretuline and Na-desacetyl-18-hydroxyisoretuline. The two latter, unknown as natural products, have already been obtained by degradation of strychnine. © 1976.