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

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 .