Metabolism and fate of ecdysteroids in the nematodes Ascaris suum and Parascaris equorum.

When injected with [3H]ecdysone and maintained in vitro, the parasitic nematodes, Ascaris suum and Parascaris equorum each produced a series of polar and relatively apolar metabolites. A. suum metabolised the compound into ecdysonoic acid ([3H]EOIC), ecdysone 25-glucoside ([3H]E25gluc), putative ecdysone 22-phosphate ([3H]E22P) and a series of at least six relatively apolar metabolites. All of these, except ecdysonoic acid, were hydrolysed by a crude enzyme preparation from Helix pomatia, releasing ecdysone. In a similar study, P. equorum produced ecdysone 25-glucoside, putative ecdysone 22-phosphate and a series of relatively apolar compounds all of which were hydrolysed by H. pomatia enzymes, releasing ecdysone. [3H]Ecdysone 25-glucoside was the most abundant single metabolite in both species, and in P. equorum, at least, was released into the culture medium in relatively large amounts. Apolar metabolites were present in worm samples and were the major, if not the only radiolabelled compounds detected in eggs of both species. Data indicated a metabolic relationship between some of the apolar conjugates found in both nematode species and ecdysone 25-glucoside.