Bulbs of Pancratium maritimum were found to contain a new glucosyloxy phenolic metabolise as well as 14 known Amaryllidaceae alkaloids. The structure of the phenolic metabolite was elucidated by spectroscopic and chemical methods, and it was identified as narciclasine-4-O-β-d-glucopyranoside. When tested in Artemia salina and potato disc assays the new glucoside showed cytotoxic and antitumour activity very similar to narciclasine. © 1991.