Identification of new fluorophores in coelomic fluid of Eisenia andrei earthworms

Coelomic fluid of Eisenia andrei contains a number of UV-fluorescent compounds. In the present study we have found that four of these compounds showed identical fluorescence excitation and emission maxima at 310 nm and 364 nm, respectively, suggesting they share the same chromophore. NMR and HR-MS spectroscopy of the most abundant fluorophore reavealed that its molecule is composed of two quinazoline-2,4-dione rings connected by spermine linker. This compound was earlier indentified in Eisenia andrei as SP-8203. Moreover, we have identified the structure of the two other fluorophores, one differing from SP-8203 by the absence of N-acetyl group, the compound not reported in any other organisms before, and the other already found in E. fetida and regarded as species specific. However, our results indicate that this metabolite is also present in E. andrei in significant amounts. The possible origin and function of these new metabolites is discussed.