Meroterpenoids from Neosetophoma sp.: A Dioxa[4.3.3]propellane Ring System, Potent Cytotoxicity, and Prolific Expression

Six fungal metabolites, of which five were new, including one (1) with a dioxa[4.3.3]propellane ring system, were discovered, identified, and structurally elucidated from Neosetophoma sp. (strain MSX50044); these compounds are similar to the bis-tropolone, eupenifeldin. Three of the meroterpenoids are potent cytotoxic agents against breast, ovarian, mesothelioma, and lung cancer cells with nanomolar IC₅₀ values while not inducing mitochondrial toxicity at 12.5 μM.