Structure Revisions of Phenolic Bisabolane Sesquiterpenes and a Ferroptosis Inhibitor from the Marine-Derived Fungus Aspergillus versicolor YPH93.

Seven new phenolic bisabolane sesquiterpenoids (-), along with 10 biogenetically related analogues (-), were obtained from the deep-sea-derived fungus YPH93. The structures were elucidated based on extensive analyses of the spectroscopic data. Compounds - are the first examples of phenolic bisabolanes that contain two hydroxy groups attached to the pyran ring. The structures of sydowic acid derivatives (- and -) were carefully studied, leading to the structure revisions of six known analogues, including a revision of the absolute configuration for sydowic acid (). All metabolites were evaluated for their effects on ferroptosis. Compound exerted inhibition on erastin/RSL3-induced ferroptosis with EC values ranging from 2 to 4 μM, while it exhibited no effects on TNFα-induced necroptosis or HO-induced cell necrosis.