Isolation of Four New Secondary Metabolites from the Cold Seep Chemosynthetic Ecosystem-Derived Fungus <i>Arachnomyces bostrychodes</i>

Ultra performance liquid chromatography (UPLC)-high resolution (HR)MS/MS and feature-based molecular networking analysis were performed for the extract of a fungus, Arachnomyces bostrychodes, obtained from a cold seep chemosynthetic ecosystem, revealing the presence of new peptides. LC-MS-guided purification afforded three new cyclic tetrapeptides (3-5) containing two N-methyl-l-leucine residues. During the isolation procedure, a new benzophenone (1) and MDN-0093 (2) were isolated. Compounds 4 and 5 exhibited cytotoxicity against HeLa cells with IC₅₀ values of 3.1 and 5.8 μM, respectively.