Fungal Metabolites .29. The Chemical Basis of Hot-tasting and Yellowing of the Mushrooms Lactarius-chrysorrheus and L-scrobiculatus

The chemical background behind yellowing and pungent taste of Lactarius chrysorrheus and L. scrobiculatus has been investigated. The intact fruit bodies originally contain a fatty acid ester of velutinal (i.e. compound 2b and 2a, respectively) as the only sesquiterpenoid. When the fruit bodies are injured the esters are enzymatically converted into sesquiterpene furans, mono- and di-aldehydes, and lactones, which have been isolated and their structures elucidated. These compounds have been submitted to conformational analysis by molecular mechanics and H-1 NMR in order to make correct stereochemical assignments. The pungent taste of the fruit bodies of both species is due to a new dialdehyde, chrysorrhedial (9), while a new triene-enolactone (8) is involved in the change of the colour.