Cytochalasin-u and Cytochalasin-v, 2 New Cytochalasins, From Phoma-exigua Var Heteromorpha

Two additional cytochalasins were isolated from liquid culture filtrates of Phoma exiqua var. heteromorpha together with some already known cytochalasins. The two new metabolites, named cytochalasin U and V, represent the first natural occurrence of a 25,26-dioxa[16] and 25-oxa[15]cytochalasan, respectively, both bearing a formyl group on the macrocyclic ring. Cytochalasins U and V showed respectively significant and weak activity in the brine shrimp assay.