Bioassay-guided isolation of cultures of Aspergillus sp. TJ23 yielded a novel terpene-polyketide hybrid spiromeroterpenoid, spiroaspertrione A (1), bearing a unique spiro[bicyclo[3.2.2]nonane-2,1'-cyclohexane] carbocyclic skeleton, and a new biointermediate, andiconin B (2). Their structures and absolute configurations were elucidated by spectroscopic analyses, single-crystal X-ray diffraction, and electronic circular dichroism calculations. Compound 1 demonstrated potent resensitization of oxacillin against methicillin-resistant Staphylococcus aureus by lowering the oxacillin minimal inhibitory concentration up to 32-fold from 32 to 1 μg/mL.

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Periconiastone A (1), an ergosterol with an unprecedented pentacyclo­[8.7.0.01,5.02,14.010,15]­heptadecane system, was isolated from Periconia sp. TJ403-rc01. Its structure was assigned by extensive spectroscopic analyses and quantum-chemical 13C NMR and ECD calculations. A vinylogous α-ketol rearrangement and an aldol condensation reaction during biosynthesis were proposed as key steps for the formation of 1. Compound 1 showed antibacterial activity against Gram-positive S. aureus and E. faecalis with MIC values of 4 and 32 μg/mL, respectively.