Cytochalasin W, a new 24‐oxa[14]cytochalasan from phoma exigua var. heteromorpha

Abstract A further cytochalasin was isolated from liquid culture filtrates of Phoma exigua var heteromorpha together with cytochalasins U and V and other well‐known cytochalasins. The metabolite, named cytochalasin W, was characterized by spectroscopic and chemical methods as a new 24‐oxa[14]cytochalasan, bearing a formyl group on the macrocyclic ring. Cytochalasin W showed toxic activity in the brine shrimp assay.