Lithocarpins E—G: Potent Anti-Tumor Tenellone-Macrolides from Deep-Sea Fungus

Abstract

Main observation and conclusion Lithocarpins E—G, featuring a rare naturally-occurring highly oxygenated tenellone-macrolide skeleton, were isolated from the culture extract of a marine-derived fungus Phomopsis lithocarpus FS508. Their structures were fully elucidated by NMR and MS spectroscopic analyses and electronic circular dichroism calculations. Compounds 1 — 3 were evaluated for their in vitro cytotoxicities against HepG2, MCF-7, SF-268, as well as A549 cell lines, among which, compound 1 exhibited inhibitory activity against HepG2 cells with an IC 50 value of 6.3 μmol/L. The further mechanistic investigation demonstrated that lithocarpin E could cause the apoptosis of HepG2 cells through activation of p-ERK, Bax, and caspase-3 gene expressions.