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E ‐ and Z ‐Proxamidines, Unprecedented 1,3‐Diazacyclooct‐1‐ene Alkaloids from Fruiting Bodies of Laccaria proxima
Author(s) -
Schrey Hedda,
Spiteller Peter
Publication year - 2019
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201900566
Subject(s) - chemistry , tryptophan , stereochemistry , pisum , biochemistry , amino acid
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 .