Lachnuoic Acids A-F: Ambuic Acid Congeners from a Saprotrophic Lachnum Species.

Chemical prospection of an extract derived from a saprotrophic fungus Lachnum sp. IW157 resulted in the isolation and characterization of six unprecedentedly reported ambuic acid analogues named lachnuoic acids A-F (1-6). Chemical structures of 1-6 were determined based on comprehensive 1D and 2D NMR spectroscopic analyses together with HR-ESI-MS spectrometry. The relative configurations of 1-3 were defined by ROESY spectroscopic analyses while their absolute configurations were unambiguously determined by Mosher's esters method. All isolated compounds were subjected to cytotoxic, antimicrobial, antibiofilm and nematicidal activity assays where only lachnuoic acid A (1) revealed potent antimicrobial activity against Staphylococcus aureus and Bacillus subtilis at MIC values of 16.6 and 8.3 µg/mL, respectively.

Diaporphasines E and F: New Polyketides from the Saprotrophic Fungus Lachnum sp. IW157 Growing on the Reed Grass Phragmites communis.

Chemical investigation for the mycelial extract of a saprotrophic fungus Lachnum sp. IW157 growing on the common reed grass Phragmites communis afforded the identification of two polyketide metabolites diaporphasines E (1) and F (2). Chemical structures of isolated compounds were unambiguously elucidated based on extensive 1D and 2D NMR spectral analyses in addition to their high-resolution mass spectrometry. The isolated compounds were assessed for their cytotoxicity and antimicrobial and biofilm inhibitory activities. While compound 1 revealed potent cytotoxicity against the tested cell lines L929 and KB3.1 with IC50 values of 0.9 and 3.7 µM, respectively, compound 2 exhibited moderate effects on the formation of S. aureus biofilms at 31.25 µg/mL.