Key Laboratory of Marine Drugs, The Ministry of Education of China, School of Medicine and Pharmacy, Ocean University of China, Qingdao 266003, People's Republic of China.
College of Food Science and Engineering, Ocean University of China, Qingdao 266003, People's Republic of China.
J Nat Prod. 2021 Apr 23;84(4):1353-1358. doi: 10.1021/acs.jnatprod.1c00098. Epub 2021 Mar 25.
Under the guidance of MS/MS-based molecular networking and HPLC-UV, two new alkaloid racemates, (±)-17-hydroxybrevianamide N () and (±)-N1-methyl-17-hydroxybrevianamide N (), featuring a rare -hydroxyphenylalanine residue and an imide subunit, were isolated from a soft-coral-derived sp. fungus. The true natural products (+)- and (+)- were further monitored and obtained from the freshly prepared EtOAc extracts, while (-)- and (-)- are artifacts generated during extraction and purification processes. Simultaneously, the structures including absolute configurations of (+)-13-, (-)-13-, (+)-13-, and (-)-13- were elucidated on the basis of comprehensive spectroscopic analysis, ECD calculations, and X-ray diffraction data. Interestingly, basic solution promotes the racemization of (+)- and (-)-, whereas acidic solution suppresses the transformation. The current research was concerned with the true natural products and their artifacts, providing critical insight into the isolation and identification of natural products.
在基于 MS/MS 的分子网络和 HPLC-UV 的指导下，从软珊瑚衍生的 sp. 真菌中分离得到了两种新的生物碱对映异构体，（±）-17-羟基缬氨酰胺 N () 和（±）-N1-甲基-17-羟基缬氨酰胺 N ()，它们具有罕见的 -羟基苯丙氨酸残基和酰亚胺亚基。真正的天然产物 (+)- 和 (+)- 进一步通过从新鲜制备的 EtOAc 提取物中监测和获得，而 (-)- 和 (-)- 则是在提取和纯化过程中产生的人工产物。同时，基于综合光谱分析、ECD 计算和 X 射线衍射数据，阐明了 (+)-13-、(-)-13-、(+)-13-和 (-)-13-的结构包括绝对构型。有趣的是，碱性溶液促进了 (+)-和 (-)-的外消旋化，而酸性溶液则抑制了这种转化。本研究关注的是真正的天然产物及其人工产物，为天然产物的分离和鉴定提供了重要的见解。
