Bioassay-Guided Isolation of Antibacterial Metabolites from Emericella sp. TJ29

Bioassay-guided isolation of metabolites from cultures of the plant-derived fungus Emericella sp. TJ29 yielded three new terpene–polyketide hybrid meroterpenoids, emervaridones A–C (1–3), two new polyketides, varioxiranediols A and B (5 and 6), and three known analogues (4, 7, and 8). The structures and absolute configurations of these new compounds were elucidated by spectroscopic analyses, single-crystal X-ray diffraction, Mo2(OAc)4-induced electronic circular dichroism (ECD) data, and ECD calculations. To date, only one compound (4) bearing the emervaridone-type carbocyclic skeleton has been reported. The structures of emervaridones A–C (1–3) are new members of this type of natural product, and 1 features the first example of an α-directional H-7′ in this structural category. Compounds 1 and 5 were active against five drug-resistant microbial pathogens [methicillin-resistant Staphylococcus aureus (MRSA), Enterococcus faecalis, extended-spectrum β-lactamase-producing Escherichia coli (ESBL-producing E. ...