The isolation and identification of the two juvenile hormones from the Cecropia silk moth

A five-step purification sequence which leads to a pure juvenile hormone preparation is described in detail. This preparation consists of two hormone molecules that were separated by micropreparative gas-liquid chromatography. The structures of the hormone molecules were identified by spectrometric microtechniques. The highresolution mass and infrared spectra of the hormones are presented and discussed. The main component of the preparation, methyl 12,14-dihomojuvenate (formula III), was found to be identical to the hormone molecule elucidated previously by the Wisconsin group. The less abundant compound, accounting for 13–20% of the juvenile hormone activity in Cecropia moths, was the new compound methyl 12-homojuvenate (formula II), which is a lower homolog of the above structure. Our earlier observation that both hormones exhibited about the same potent morphogenetic activity when assayed in Lepidoptera was confirmed; their effectiveness in other insect species is discussed. The two hormones induced ovarian development in species in which this process is under control of the corpora allata. No methyl juvenate (formula I) was present in the examined extracts, nor were there any trans-10 isomers of the hormones detected. The reactivity of the hormone molecules complicated their isolation in pure form. Some interfering reactions were recognized after the compounds had been isolated. Thus we were able to substantiate the presence of noxious contaminants in high-grade solvents and to prescribe procedures for purifying and testing the necessary solvents. Furthermore, the compounds were coverted under conditions of thermal metal catalysis in a manner that indicates the occurrence of a series of most interesting cyclization and rearrangement reactions. To avoid any such destructive conversion in our analytical and micropreparative gas-liquid chromatographic system, a metal-free sample injector and effluent splitter were constructed. It was also essential to neutralize the liquid phases before preparing the gas chromatographic supports. If the hormones were chromatographed on columns for which this precaution had not been taken, acid traces remaining in many ordinary commercial liquid phases transformed a fraction of the applied hormone to Compound A, and thus gave rise to ambiguous analyses of the unsaturated epoxides in our high-sensitivity system. The behavior of the hormones under alkaline and acidic conditions is discussed. The main product of III obtained