Research on the Metabolites and Antibacterial Activities of the Endophytic Fungus <i>Talaromyces primulinus</i> WZ‐883 From <i>Pseudostellaria heterophylla</i>

Investigation of the secondary metabolites from the endophytic fungus Talaromyces primulinus WZ-883, derived from the leaf of fresh Pseudostellaria heterophylla, led to the isolation of one new meroterpenoid, talapenoid A (1), and one new isocoumarin, talaromarin A (5), along with eight known compounds chrodrimanin B (2), chrodrimanin E (3), carnemycin B (4), aspergillumarin A (6), aspergillumarin B (7), 4-hydroxy-2,2-dimethyl-3,4-dihydrochromene-6-carboxylic acid (8), penicichrysogene B (9), and 1-naphthalenecarboxylic acid (10). Their structures were primarily determined through extensive spectroscopic analyses. The configurations were assigned using ROESY spectra, ECD, and NMR calculations, as well as x-ray single crystal diffraction. Among them, compound 1 is an uncommon meroterpenoid featuring a 5/6/6/6-pentacyclic α-pyrone skeleton. All isolated compounds were evaluated for their inhibitory effects on pathogenic bacteria. Compounds 1-4 and 9 exhibited selective antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA), S. aureus, Enterococcus faecalis, and Escherichia coli, but showed no significant activity against Shigella sonnei and Klebsiella pneumoniae.