Longitubine and Neolatifoline, New Pyrrolizidine Alkaloids From Hackelia longituba

Abstract

Methanolic extracts of freeze-dried Hackelia longituba I. M. Johnston (Boraginaceae) afforded two new pyrrolizidine alkaloids: longitubine (1), an analogue of latifoline (2) in which an acetoxy group has replaced the angeloxy group at C7 and neolatifoline (3a) or (3b), a diastereomer of latifoline esterified at C9 with a stereoisomer of latifolic acid. In addition, the known alkaloids latifoline (2), 9-angelylretronecine (4) and 7-angelylretronecine (5) were isolated and identified.