Characterization of Leptazolines A–D, Polar Oxazolines from the Cyanobacterium Leptolyngbya sp., Reveals a Glitch with the “Willoughby–Hoye” Scripts for Calculating NMR Chemical Shifts

The bioactivity-guided examination of a Leptolyngbya sp. led to the isolation of leptazolines A–D (1–4), from the culture media, along with two degradation products (5 and 6). Density functional theory nuclear magnetic resonance calculations established the relative configurations of 1 and 2 and revealed that the calculated shifts depended on the operating system when using the “Willoughby–Hoye” Python scripts to streamline the processing of the output files, a previously unrecognized flaw that could lead to incorrect conclusions.

本研究通过生物活性导向的考察，从一株鞘丝藻属（Leptolyngbya sp.）的培养基中分离得到莱普唑啉A-D（leptazolines A-D，1~4），同时分离得到两种降解产物（5和6）。借助密度泛函理论核磁共振计算，确定了化合物1与2的相对构型，并发现当使用“威洛比–霍伊”Python脚本（Willoughby–Hoye Python scripts）优化输出文件的处理流程时，计算得到的化学位移会因操作系统不同而存在差异，这是此前未被发现的、可能导致错误结论的缺陷。