Cyclic Heptapeptides, Cordyheptapeptides C–E, from the Marine-Derived Fungus <i>Acremonium persicinum</i> SCSIO 115 and Their Cytotoxic Activities

Three new cycloheptapeptides, cordyheptapeptides C–E (<b>1</b>–<b>3</b>), were isolated from the fermentation extract of the marine-derived fungus <i>Acremonium persicinum</i> SCSIO 115. Their planar structures were elucidated on the basis of extensive MS, as well as 1D and 2D (COSY, HMQC, and HMBC) NMR spectroscopic data analyses. The absolute configurations of the amino acid residues were determined by single-crystal X-ray diffraction, Marfey’s method, and chiral-phase HPLC analysis. Compounds <b>1</b> and <b>3</b> displayed cytotoxicity against SF-268, MCF-7, and NCI-H460 tumor cell lines with IC₅₀ values ranging from 2.5 to 12.1 μM