Discovery of a Hepatoprotective Trinor-Sesterterpenoid from the Marine Fungus Talaromyces sp. Against Hepatic Ischemia-Reperfusion Injury

A new trinor-sesterterpenoid penitalarin D (1), with a 3,6-dioxabicyclo[3.1.0]hexane moiety, as well as two known compounds, penitalarin C (2) and nafuredin A (3), were obtained from the mangrove sediment-derived Talaromyces sp. SCSIO 41412. Their structures were determined by detailed NMR, MS spectroscopic analyses, and ECD calculations. Penitalarin D (1) and nafuredin A (3) showed toxicity or no toxicity against HepG2 cells at a concentration of 200 μM. The transcriptome sequencing and bioinformatics analysis revealed that 3 could be effective by regulating ferroptosis pathways in HepG2 cells, which was subsequently validated by RT-qPCR, demonstrating significant upregulation of ferroptosis-related genes. Pre-treatment with 3 could mitigate hypoxia-reoxygenation-induced damage in the oxygen glucose deprivation/reperfusion (OGD/R) cell model. Given the structural similarity of compounds 1, 2, and 3, we also screened compounds 1 and 2 in an AML12 OGD/R model. As no significant activity was observed, compound 3 was selected for subsequent in vivo studies. Subsequently, in vivo experiments demonstrated that 3 could significantly decrease pro-inflammatory cytokines and display the hepatoprotective effects against hepatic ischemia-reperfusion injury (HIRI). These findings identified nafuredin A (3) as a promising hepatoprotective agent for new drug development.