Psychrophilins E–H and Versicotide C, Cyclic Peptides from the Marine-Derived Fungus Aspergillus versicolor ZLN-60

Four new cyclic peptides, psychrophilins E–H (1–4), possessing a rare amide linkage between the carboxylic acid in anthranilic acid (ATA) and the nitrogen from an indole moiety, along with a new ATA-containing hexapeptide, versicotide C (5), were obtained from the culture of the marine-derived fungus Aspergillus versicolor ZLN-60. The structures, including absolute configurations, were elucidated by a combination of HRESIMS, NMR, X-ray crystallography, TDDFT ECD calculations, and Marfey’s method. Versicotide C (5) is the first natural cyclic hexapeptide containing two anthranilic acids. Compounds 1–5 were not cytotoxic, and compound 3 showed potent lipid-lowering effects.

从海洋来源真菌杂色曲霉（Aspergillus versicolor）ZLN-60的发酵培养物中，分离得到4个新型环肽——嗜冷菌素E~H（1~4），其结构中含有罕见的邻氨基苯甲酸（anthranilic acid，ATA）羧基与吲哚基团氮原子形成的酰胺键；同时还获得1个含ATA的新型六肽杂色肽C（versicotide C，5）。本研究通过高分辨电喷雾电离质谱（HRESIMS）、核磁共振波谱（NMR）、X射线单晶衍射、时间依赖密度泛函理论电子圆二色谱（TDDFT ECD）计算以及马尔菲伊分析法（Marfey's method）联用，解析了包括绝对构型在内的所有化合物的完整结构。其中，杂色肽C（5）是首例含两个邻氨基苯甲酸单元的天然环六肽。化合物1~5均未表现出细胞毒性，而化合物3展现出显著的降脂活性。