Emestrin-type epipolythiodioxopiperazines from Aspergillus nidulans with cytotoxic activities by regulating PI3K/AKT and mitochondrial apoptotic pathways

Five novel emestrin-type epipolythiodioxopiperazines (ETPs), prenylemestrins C-G (1-5), along with two known ETPs, prenylemestrin A (6) and prenylemestrin B (7), were obtained from Aspergillus nidulans. Their structures were characterized by spectroscopic data, X-ray crystallographic data, ECD comparisons and calculations. Prenylemestrins C-G (1 - 5) represent a rare class of ETPs, characterized by a 2,5-dithia-7,9-diazabicyclo[4.2.2]decane-8,10-dione core involving a hemiterpene moiety. Notably, compound 6 exhibited moderate cytotoxicity, inducing G2/M cell cycle arrest and apoptosis of L1210 cells by regulating the PI3K/AKT signaling pathway and mitochondrial apoptotic mechanisms.