Talasteroid, a new withanolide from the marine-derived fungus Talaromyces stollii

A new withanolide, talasteroid (1), and a known steroid (2), along with eight meroterpenoids (3–10), were obtained from the rice culture of the marine-derived fungus Talaromyces stollii HBU-115. The structure of 1 including its absolute configuration was determined by extensive 1 D and 2 D NMR spectroscopy, and single-crystal X-ray diffraction analysis. Compound 1 represents the first withanolide featuring a 4-substituted 2,3-dimethyl-2-butenolide ring in the side chain. The isolated compounds were evaluated for their antimicrobial and antioxidant activities.