In vitro metabolism of possible ecdysone precursors by the prothoracic glands of the tobacco hornworm, Manduca sexta.
3 beta, 14 alpha-Dihydroxy-5 alpha-7-en-6-one (5 alpha-ketodiol) (1) is metabolized by the prothoracic glands to 2,22-dideoxy-5 alpha-ecdysone (4) and 2-deoxy-5 alpha-ecdysone (3) but not to ecdysone (5) or any other 5 beta-metabolites. Similarly, 3 beta,5 alpha,14 alpha-trihydroxy-cholest-7-en-6-one (5 alpha-ketotriol) (8) is hydroxylated at C-22 and C-25 (9,10) of the side chain. However, 3 beta,14 alhpa-dihydroxy-cholesta-4,7-diene-6-one (ketodienediol) (11) is not metabolized. The absence of 2 beta-hydroxymetabolites for substrates (1) and (8) implies that hydroxylation at C-2 can occur only when the A-B rings are cis fused (5 beta-configuration). By contrast, the enzyme complexes that introduce hydroxyls at C-22 and C-25 do not exhibit a preference for cis over trans fusion and appraently cannot recognize the planar A-B ring configuration.
D000818:Animals; D002851:Chromatography, High Pressure Liquid; D004440:Ecdysone / Q000096:biosynthesis*; D004702:Endocrine Glands / Q000378:metabolism*; D066298:In Vitro Techniques; D007814:Larva; D007915:Lepidoptera / Q000378:metabolism*; D009036:Moths / Q000378:metabolism*
D004440:Ecdysone