New Polyketides from a Marine Sponge-Derived Fungus, Neopestalotiopsis sp., with Anti-Renal Fibrosis Activity

Sixteen polyketides, including six new compounds (1–2, and 5–8), were isolated from the culture of the marine sponge-associated fungus Neopestalotiopsis sp. SCSIO 41422. Their structures were elucidated through NMR, MS spectroscopic analyses, calculated electronic circular dichroism, quantum chemical NMR calculations, and X-ray single-crystal diffraction. To screen and evaluate the inhibitory activity of these polyketides in renal fibrosis, a TGF-β1-stimulated HK-2 cell model was used. All tested compounds (1, 5–8, and 11–12) at 10 µM showed obvious anti-fibrotic activity by inhibiting TGF-β1-induced α-SMA expression and extracellular matrix production (collagen I and fibronectin). Among them, gamahorin A (1) was shown to be the most potent and the most promising inhibitor against renal fibrosis.