Aromatic metabolites from the coelomic fluid of Eisenia earthworm species

Earthworms from the genus Eisenia express coelomic fluid when under severe stress. This coelomic fluid contains a complex mixture of small-molecule metabolites, including aromatic metabolites which are known to be species-specific, yet their actual identities remain unknown. We have aimed to characterize selected high-concentration coelomic fluid metabolites. The major aromatic compound in Eisenia veneta coelomic fluid is the rare metabolite a-nicotinamide riboside; and the major aromatic compound for Eisenia fetida is closely related to the (already characterized) metabolite of Eisenia andrei, which consists of two aromatic quinazoline-2,4-dione ring structures linked by N-acetylspermine. The biological function(s) of these metabolites in earthworms is unknown, but we hypothesize that they represent remnants of larger molecules, possibly bacterial in origin, that are recalcitrant to metabolism by earthworm enzymes. (C) 2016 The Authors. Published by Elsevier Masson SAS.