title: The stereochemistry of hydrogen elimination from C-7 during biosynthesis of ecdysones in insects and plants.
abstract: 1. [7alpha-(3)H(1)]- and [7beta-(3)H(1)]-Cholesterol were synthesized by a modified method. 2. The stereochemistry of Delta(7)-bond formation during ecdysone and ecdysterone biosynthesis in the insect, Calliphora erythrocephala and the plants, Taxus baccata and Polypodium vulgare was investigated by using [4-(14)C,7alpha-(3)H(1)]cholesterol and [4-(14)C,7beta-(3)H(1)]cholesterol. 3. In each case, the 7beta hydrogen was stereospecifically eliminated. 4. The possible significance of the results is discussed in relation to double-bond formation in other systems and the stage at which the Delta(7) bond is introduced during ecdysone biosynthesis.
mesh_terms: D000818:Animals; D002250:Carbon Radioisotopes; D002784:Cholesterol / Q000378:metabolism; D004175:Diptera / Q000378:metabolism*; D004440:Ecdysone / Q000096:biosynthesis*; D006859:Hydrogen / Q000378:metabolism; D007447:Invertebrate Hormones / Q000096:biosynthesis; D007553:Isotope Labeling; D010084:Oxidation-Reduction; D010944:Plants / Q000378:metabolism*; D013237:Stereoisomerism; D014316:Tritium
chemical_list: D002250:Carbon Radioisotopes; D007447:Invertebrate Hormones; D014316:Tritium; D004440:Ecdysone; D006859:Hydrogen; D002784:Cholesterol