Ergochaeglobosins A—E, Unprecedented Heterodimers of Cytochalasan and Ergosterol fromChaeglobosin globosumP2‐2‐2

Comprehensive Summary Five novel heterodimers of cytochalasan and ergosterol, ergochaeglobosins A—E, were isolated from an endophytic fungus Chaetomium globosum P2‐2‐2. Ergochaeglobosin A (1) possesses an unprecedented 5/6/13/6/5/6/6/6 fused octacyclic ring system, and ergochaeglobosins B (2) and C (3) form a unique 5/6/13/6/6/6/6/5 fused octacyclic ring system, whereas ergochaeglobosins D (4) and F (5) are the first cytochalasan heterodimers formed via a N‐1′/C‐3′′ single bond. Their structures with absolute configurations were established by extensive spectroscopic analyses, single‐crystal X‐ray diffraction, and ECD calculations. The plausible biogenetic pathway of 1—5 was postulated. Compound 1 exhibited inhibitory effects against ConA‐induced T cells and LPS‐induced B cells proliferation with IC 50 values of 19.2 and 14.1 μmol/L, respectively. Co‐treatment of 3 (20 μmol/L) with TRAIL (150 ng/mL) could significantly decrease the cell viability of A549 by 24.9% comparing with monotherapy of 3 (20 μmol/L).