A major metabolite of [3H]ecdysone injected into adults of the nematode Parascaris equorum maintained in vitro for 48 h was secreted into the culture medium. The compound could be hydrolysed with a crude hydrolase preparation from Helix pomatia, yielding ecdysone. Sufficient quantity of this material for identification was produced by administration of ecdysone to the parasites. The resulting compound was purified by h.p.l.c. and identified as ecdysone 25-O-beta-D-glucopyranoside by n.m.r. spectroscopy and by fast atom bombardment mass spectrometry of the conjugate and of the sugar released by enzymic hydrolysis. The significance of formation of the glucoside is uncertain.
