Pyrrolizidine alkaloids from Echium glomeratum (Boraginaceae)

Five pyrrolizidine alkaloids were isolated from Echium glomeratum Poir. (Boraginaceae). Three of these were (7S, 8R)-petranine (1), (7S, 8S)-petranine (2), and (7R, 8R)-petranine (3a) or (7R, 8S)-petranine (3b), and two were known but to the species: 7-angeloylretronecine (4) and 9-angeloylretronecine (5).