Plectosphaeroic Acids A, B, and C, Indoleamine 2,3-Dioxygenase Inhibitors Produced in Culture by a Marine Isolate of the Fungus Plectosphaerella cucumerina

Laboratory cultures of the fungus Plectosphaerella cucumerina obtained from marine sediments collected in Barkley Sound, British Columbia, yielded the novel alkaloids plectosphaeroic acids A (1) to C (3). The alkaloids 1-3 are inhibitors of indoleamine 2,3-dioxygenase (IDO).