Isolation and identification of apolar metabolites of ingested 20-hydroxyecdysone in frass ofHeliothis virescens larvae

A large amount of 20-hydroxyecdysone was orally administered to larvae of the tobacco budworm,Heliothis virescens, in order to investigate its detoxification mechanisms. Four major relatively nonpolar metabolites were isolated from their frass. These compounds were identified as the 22-linoleate, 22-palmitate, 22-oleate, and 22-stearate of 20-hydroxyecdysone using various forms of spectroscopy, including NMR. This is the first report of this type of metabolite from an insect.