Enzymatic and chemical synthesis of 3-dehydroecdysterone, a metabolite of the moulting hormone of insects.

3-Dehydroecdysterone, a less polar metabolite of ecdysterone, was synthesized in vitro using either an enzyme (edcysone oxidase, EC 1.1.3.16) or the chemical catalyst platinum. 3-Dehydroecdysterone was purified and characterized by its chromatographic behaviour, its staining properties and by UV, IR, NMR and mass spectroscopy. The compound is 1/15 as active as ecdysone in the Calliphora moulting hormone bioassay. Its biological relevance is discussed.