Protoilludane-type sesquiterpenoids from Armillaria sp. by co-culture with the endophytic fungus Epicoccumsp. associated with Gastrodia elata.

An investigation of a co-culture of the Armillaria sp. and endophytic fungus Epicoccum sp. YUD17002 associated with Gastrodia elata led to the isolation of eight new compounds, including five protoilludane-type sesquiterpenes (1-5) and three aryl esters (6-8), together with six known analogues (9-14). The assignments of their structures were conducted via extensive analyses of the spectroscopic data and comparison of experimental and calculatedelectronic circular dichroism(ECD)data. Notably, these new compounds were not present in the pure culture controls and were only detected in the co-cultures. Compound 4 is the first example of an ent-protoilludane sesquiterpenoid scaffold bearing a five-membered lactone. Compound 6 exhibited moderate in vitro cytotoxic activities against five human cancer cell lines (HL-60, A549, MCF-7, SMMC-7721, and SW480) with IC₅₀ values ranging from 15.80 to 23.03 μM. Moreover, 6 showed weak acetylcholinesterase inhibitory activity (IC₅₀ value of 23.85 μM).