Evodialones A and B: Polyprenylated Acylcyclopentanone Racemates with a 3‑Ethyl-1,1-diisopentyl-4-methylcyclopentane Skeleton from <i>Evodia lepta</i>

Two polyprenylated acylcyclopentanone racemates, evodialones A (<b>1</b>) and B (<b>2</b>), featuring a 3-ethyl-1,1-diisopentyl-4-methylcyclopentane skeleton, were isolated from an extract of the aerial parts of <i>Evodia lepta</i>. Evodialone A (<b>1</b>) was resolved by chiral-phase HPLC to afford a pair of enantiomers, (+)- and (−)-evodialones A (<b>1b</b>/<b>1a</b>), while evodialone B (<b>2</b>) could not be resolved. Their structures were elucidated by spectroscopic analysis and a combination of computational techniques including gauge-independent atomic orbital calculation of 1D NMR data and experimental and TDDFT-calculated ECD spectra. A putative biosynthetic pathway of <b>1</b> and <b>2</b> starting from the monocyclic polyprenylated acylphloroglucinols is proposed. All the isolates were screened for the antimicrobial activity in vitro, and <b>1a</b> and <b>1b</b> showed moderate inhibitory activities against several pathogenic fungi with MICs values of 17.1–68.3 μM