Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD 4072, Australia.
Natural Products Discovery Core, Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA.
Mar Drugs. 2021 Mar 12;19(3):151. doi: 10.3390/md19030151.
Further investigation into a fish gut-derived fungus sp. CMB-F563, previously reported to produce the unprecedented Schiff base prolinimines A-B (-), revealed a new cryptic natural product, -amino-l-proline methyl ester ()-only the second reported natural occurrence of an -amino-proline, and the first from a microbial source. To enable these investigations, we developed a highly sensitive analytical derivitization methodology, using 2,4-dinitrobenzaldehyde (2,4-DNB) to cause a rapid in situ transformation of to the Schiff base , with the latter more readily detectable by UHPLC-DAD (400 nm) and HPLC-MS analyses. Moreover, we demonstrate that during cultivation is retained in fungal mycelia, and it is only when solvent extraction disrupts mycelia that is released to come in contact with the furans - (which are themselves produced by thermal transformation of carbohydrates during media autoclaving prior to fungal inoculation). Significantly, on contact, undergoes a spontaneous condensation with - to yield the Schiff base prolinimines -, respectively. Observations made during this study prompted us to reflect on what it is to be a natural product (i.e., ), versus an artifact (i.e., -), versus a media component (i.e., -).
进一步研究一种先前报道过能产生前所未有的席夫碱脯氨酸亚胺 A-B(-)的鱼肠真菌 sp. CMB-F563，揭示了一种新的隐色天然产物，-氨基-L-脯氨酸甲酯(-)——仅有的第二个报道的 -氨基-脯氨酸天然产物，也是第一个来自微生物源的 -氨基-脯氨酸天然产物。为了进行这些研究，我们开发了一种高灵敏度的分析衍生化方法，使用 2,4-二硝基苯甲醛 (2,4-DNB) 引起快速原位转化为席夫碱，后者更易于通过 UHPLC-DAD(400nm) 和 HPLC-MS 分析检测。此外，我们证明在培养过程中保持在真菌菌丝体中，只有当溶剂提取破坏菌丝体时，才会释放与呋喃(-接触，-本身是在真菌接种前培养基高压灭菌过程中碳水化合物热转化产生的)。重要的是，接触时，-会自发与 -缩合分别生成席夫碱脯氨酸亚胺-。在这项研究中观察到的现象促使我们思考什么是天然产物(即 -)，什么是人工制品(即 -)，什么是培养基成分(即 -)。
