Dactylfungins and Tetralones: Bioactive Metabolites from a Nematode-Associated Laburnicola nematophila .

A chemical investigation of Laburnicola nematophila , isolated from cysts of the plant parasitic nematode Heterodera filipjevi , affored three dactylfungin derivatives ( 1 - 3 ) and three tetralone congeners ( 4 - 6 ). Dactylfungin C ( 1 ), laburnicolin ( 4 ), and laburnicolenone ( 5 ) are previously undescribed natural products. Chemical structures of the isolated compounds were determined based on 1D and 2D NMR spectroscopic analyses together with HR-ESI-MS spectrometry and comparison with data reported in the literature. The relative configurations of compounds 1 , 2 , and 4 - 6 were determined based on their ROESY data and analysis of their coupling constants ( J values). The absolute configurations of 4 - 6 were determined through the comparison of their measured and calculated TDDFT-ECD spectra. Compounds 1 - 3 were active against azole-resistant Aspergillus fumigatus .