Polycyclic meroterpenoids, talaromyolides E - K for antiviral activity against pseudorabies virus from the endophytic fungus Talaromyces purpureogenus

Anti-pseudorabies virus (PRV) activity-guided isolation of an endophytic fungus Talaromyces purpureogenus resulted in seven rare polycyclic meroterpenoids talaromyolides E-K, together with two known compounds preaustinoid and austinolide. Their structures and absolute configurations were elucidated by HRESIMS, extensive NMR spectroscopic analyses, time-dependent density functional theory (TDDFT) calculations of ECD spectra, and single crystal X-ray diffraction. Talaromyolides I and K showed a dose-dependent inhibition of PRV, of which talaromyolide K had the most potent inhibition effect rate (60.11%), blocking effect rate (53.24%) and killing effect rate (62.16%) at a concentration of 50 mu g/mL. A plausible biosynthetic pathway for talaromyolides E-K was proposed. (C) 2020 Elsevier Ltd. All rights reserved.