1. N -Amino-l-Proline Methyl Ester from an Australian Fish Gut-Derived Fungus: Challenging the Distinction between Natural Product and Artifact.
- Author
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Mohamed OG, Khalil ZG, and Capon RJ
- Subjects
- Animals, Ascomycota isolation & purification, Australia, Benzaldehydes chemistry, Biological Products chemistry, Biological Products isolation & purification, Chromatography, High Pressure Liquid, Mass Spectrometry, Schiff Bases chemistry, Solvents chemistry, Ascomycota chemistry, Fishes microbiology
- Abstract
Further investigation into a fish gut-derived fungus Evlachovaea sp. CMB-F563, previously reported to produce the unprecedented Schiff base prolinimines A-B ( 1 - 2 ), revealed a new cryptic natural product, N -amino-l-proline methyl ester ( 5 )-only the second reported natural occurrence of an N -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 5 to the Schiff base 9 , with the latter more readily detectable by UHPLC-DAD (400 nm) and HPLC-MS analyses. Moreover, we demonstrate that during cultivation 5 is retained in fungal mycelia, and it is only when solvent extraction disrupts mycelia that 5 is released to come in contact with the furans 7 - 8 (which are themselves produced by thermal transformation of carbohydrates during media autoclaving prior to fungal inoculation). Significantly, on contact, 5 undergoes a spontaneous condensation with 7 - 8 to yield the Schiff base prolinimines 1 - 2 , respectively. Observations made during this study prompted us to reflect on what it is to be a natural product (i.e., 5 ), versus an artifact (i.e., 1 - 2 ), versus a media component (i.e., 7 - 8 ).
- Published
- 2021
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