Didymorenloids A and B, two polycyclic cyclopenta[b]fluorene-type alkaloids with anti-hepatoma activity from the mangrove endophytic fungus Didymella sp. CYSK-4

Molecular networking guidance lead to the isolation of a new cyclopenta[ b ]fluorene-type alkaloid didymorenloid A (1), containing an unprecedented 6/5/6/5/13(6)/5/5/5-fused ring system, from the mangrove endophytic fungus Didymella sp. CYSK-4.