Isolation and identification of 3-acetylecdysone 2-phosphate, a metabolite of ecdysone, from developing eggs of Schistocerca gregaria

Abstract

A major ecdysteroid conjugate, which accumulates in the eggs of the desert locust, S. gregaria, during the later stages of embryogenesis, was isolated by reversed-phase and anion-exchange high-performance liquid chromatography. Hydrolysis of the conjugate with a crude arylsulfatase preparation from Helix pomatia liberates mainly ecdysone 3-acetate. The compound was identified as 3-acetylecdysone 2-phosphate by phosphate analysis of an acid-hydrolyzed sample, fast atom bombardment, electron impact and chemical ionization mass spectrometry and 1H and 13C NMR spectroscopy. The instability of 3-acetylecdysone 2-phosphate on storage results in the formation of ecdysone 2-phosphate, which was identified by physicochemical techniques. 3-Acetylecdysone 2-phosphate and ecdysone 2-phosphate are less susceptible than ecdysone 22-phosphate to hydrolysis in vitro by an enzyme preparation from S. gregaria embryos. The possible role of 3-acetylecdysone 2-phosphate as an inactive end product of ecdysteroid metabolism is discussed.