SYNTHESIS OF HIGH SPECIFIC ACTIVITY -7-DEHYDROCHOLESTEROL. CONVERSION TO ECDYSONE IN FOLLICLE CELLS OF LOCUSTA (INSECTS)

Article abstract of DOI:10.1016/S0040-4020(01)87837-6

In previous studies we have characterized the last steps of the biosynthetic pathway of the insect moulting hormone ecdysone.We are now extending our studies to the early steps and have postulated that 7-dehydrocholesterol is one of the earliest precursor molecules.To probe this hypothesis we have synthesized this molecule under tritiated form with high specific activity (2 TBq/mmol).We have devised an original pathway which includes, as a last step, the tritiation at positions 1α and 2α.In a first series of investigations, we have demonstrated that injected 7-dehydrocholesterol was efficiently converted in vivo by the ovaries of adult females of Locusta migratoria into conjugated ecdysone and 2-deoxyecdysone.In vitro incubations of 7-dehydrocholesterol with a 1.000g supernatant of a follicle cell homogenate have occasionaly yielded conversion rates into ecdysone which were as high as 10percent.