title: Mechanism of formation of the A/B cis ring junction of ecdysteroids in Polypodium vulgare.
abstract: 1. The fates of the alpha-, 4 alpha- and 4 beta-hydrogen atoms of cholesterol during formation of the A/B cis ring junction of ecdysteroids was investigated by administration of [4-14C, 3 alpha-3H], [4-14C, 4 alpha-3H]- and [4-14C, 4 beta-3H]cholesterol species to the fern, Polypodium vulgare, and isolation of the 20-hydroxyecdysone formed in each case. 2. The 3H was retained in the ecdysteroid formed from each substrate. 3. Location of the 3H in the 20-hydroxyecdysone indicated that migration of 3H from the 3 alpha- and 4 beta-positions to C-4 and C-5, respectively, had occurred, whereas the 4 alpha-3H atom was retained at C-4. 4. A possible mechanism for the formation of the A/B cis ring junction of ecdysteroids in P. vulgare is presented.
mesh_terms: D002250:Carbon Radioisotopes; D055598:Chemical Phenomena; D002621:Chemistry; D002784:Cholesterol / Q000378:metabolism; D004441:Ecdysterone / Q000096:biosynthesis* / Q000302:isolation & purification; D008956:Models, Chemical; D010944:Plants / Q000378:metabolism*; D014316:Tritium
chemical_list: D002250:Carbon Radioisotopes; D014316:Tritium; D004441:Ecdysterone; D002784:Cholesterol