N2-(1-Methoxycarbonylethyl)guanosine, a new nucleoside coupled with an amino acid derivative from Amanita exitialis

A new purine nucleoside coupled with an amino acid derivative, N2-(1-methoxycarbonylethyl)guanosine 1, along with β-carboline and russulaceramide was isolated from the fruiting bodies of Amanita exitialis, a newly described poisonous mushroom. Its structure was elucidated by spectroscopic methods. This is the first report of naturally occurring nucleosides in which an α-amino acid derivative is bonded through its α-amino nitrogen to a nucleobase aglycone by a C–N bond. The new compound was found to be toxic in brine shrimp lethality test (BST).