E‐ and Z‐Proxamidines, Unprecedented 1, 3‐Diazacyclooct‐1‐ene Alkaloids from Fruiting Bodies of Laccaria proxima. Issue 34 (17th May 2019)

• Record Type: Journal Article
• Authors: Schrey, Hedda; Spiteller, Peter
• Is Part Of: Chemistry. Volume 25:Issue 34(2019)
• Page Start: 8035
• Page End: 8042
• Publication Date: 2019-05-17
• Subjects: 1, 3-diazacyclooct-1-enes -- alkaloids -- amidines -- fungi -- natural products; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201900566
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: Fruiting bodies of Laccaria proxima were screened for the presence of new secondary metabolites by means of HPLC‐UV and LC‐HR‐(+)‐ESIMS. Thus, two isomeric alkaloids with a highly unusual core structure, E ‐proxamidine and its Z ‐isomer, were isolated from Laccaria proxima . The proxamidines consist of an eight‐membered heterocyclic ring system with a formamidine unit. The structures were established by 2D NMR spectroscopic methods, HR‐(+)‐ESIMS, and HR‐(+)‐ESIMS/MS. The proxamidines are probably biosynthetically derived from tryptophan, dimethylallyl pyrophosphate, and S ‐adenosylmethionine and the eight‐membered ring of the proxamidines is likely to be generated by a rearrangement of the tryptophan sceleton. Metabolic profiling of fruiting bodies of some other Laccaria species revealed that the proxamidines appear in significant amounts only in L. proxima making the compounds suitable as chemotaxonomic markers. E ‐Proxamidine exhibits herbicidal activity against Lepidium sativum . Abstract : Fungi : Two alkaloids, E ‐proxamidine and Z ‐proxamidine (see graphic), have been isolated from Laccaria proxima . The structures are highly unusual in nature, possessing an eight‐membered heterocyclic ring system with a formamidine unit. Metabolic profiling of the crude extract for potential biosynthetic intermediates allowed a hypothetical biosynthesis to be proposed for the proxamidines. E ‐proxamidine exhibits herbicidal activity against Lepidium sativum .