Corallomycetellains A–J, Cytotoxic Epipolythiodioxopiperazine Alkaloids Isolated from the Fungi Corallomycetella repens HDN23-0007

Ten new epipolythiodioxopiperazine (ETP) alkaloids, named corallomycetellains A–J (1–10), along with one known analogue, haematocin (11), were isolated from the fungi Corallomycetella repens HDN23-0007. Their structures, including absolute configurations, were established by comprehensive spectroscopic data and electronic circular dichroism (ECD) calculations. Compounds 1–2 represent the first two examples of aranotin-type ETPs possessing an aromatic indole moiety. Compounds 2–4 all featured a unique C2-methyl disulfide substituent, whereas compound 4 additionally possessed a C2′-oxomethyl group. In in vitro cytotoxicity assays, compounds 7–10, which contained α–α′ polysulfide bridges, exhibited strong anticancer activity, with IC50 values ranging from 1.1 to 9.3 μM.