Cordypyridones E-J: Antibiofilm 2-Pyridone Alkaloids from the Nematode Antagonistic Fungus Laburnicola nematophila

Abstract

In the course of biochemical prospection of Laburnicola nematophila isolated from eggs of the plant-parasitic cyst nematode Heterodera filipjevi, eight 2-pyridone alkaloids were isolated from its solid-state BRFT cultures and identified as six previously undescribed, cordypyridones E-J (1-6), and two known congeners, cordypyridones C (7) and D (8). The structures and absolute configurations of all isolated compounds were elucidated through HR-ESI-MS, 1D/2D NMR spectroscopy, and TDDFT-ECD calculations. Compound 4, bearing a rare N-hydroxy-2-pyridone moiety structurally related to that of PF1140, exhibited broad-spectrum bioactivity in cytotoxicity and antimicrobial assays. Compounds 5 and 6 demonstrated potent antibiofilm activities against Staphylococcus aureus, reducing its biofilm formation by almost 50% at 0.25 and 7.8 μg/mL, respectively.