Periconiastone A, an Antibacterial Ergosterol with a Pentacyclo[8.7.0.0^1,5.0^2,14.0^10,15]heptadecane System from <i>Periconia</i> sp. TJ403-rc01

Abstract

Periconiastone A (<b>1</b>), an ergosterol with an unprecedented pentacyclo[8.7.0.0^1,5.0^2,14.0^10,15]heptadecane system, was isolated from <i>Periconia</i> 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 <b>1</b>. Compound <b>1</b> showed antibacterial activity against Gram-positive <i>S. aureus</i> and <i>E. faecalis</i> with MIC values of 4 and 32 μg/mL, respectively.