Isolation and identification of two isomeric glutamylselenocystathionines from the seeds of Astragalus pectinatus

Two glutamylselenocystathionines have been isolated from the seeds of Astragalus pectinatus. These have been identified as 2-γ-glutamylamino-4-(2-amino-2-carboxyethylselenyl) butyric acid and 2-amino-4-(2-γ-glutamylamino-2-carboxyethylselenyl) butyric acid. The evidence for the natural occurrence of the corresponding glutamylcystathionines is also presented.