A novel antibacterial tyroscherin derivative with a natural unprecedented morpholine-2, 3-dione structural unit from the fungus Pseudallescheria boydii .

A novel tyroscherin derivative named pseudallecin A () with a natural unprecedented morpholine-2, 3-dione structural unit, and a new biogenic synthesis related organic acid named pseudallecin B () were purified from a symbiotic fungus derived from . Their structures were elucidated via spectroscopic analyses and ECD calculation. Pseudallecin A exhibited strong inhibitory activities against both Gram-positive and Gram-negative .