Relationship between the absolute configuration and the biological activity of juvenile hormone III

The activity of the pure 10R (=natural) and 10S enantiomers of juvenile hormone III (JH III) was determined in 3 different bioassays, and the relative binding affinity of the 2 enantiomers to the haemolymph JH-binding protein of the cockroachNauphoeta cinerea was measured. In theGalleria wax test, a local morphogenetic assay, the 10R enantiomer was 5240 times more active than, the 10S enantiomer, 1Galleria unit corresponding to 0.42 pg of 10R-JH III as compared to 2.2 ng for 10S-JH III. In a systemic morphogenetic assay with the cockroachNauphoeta cinerea 380 times less 10R enantiomer was necessary in order to induce detectable juvenilisation (58 ng 10R and 22 μg 10S) and in a systemic gonadotropic assay withNauphoeta cinerea 255 times less 10R was needed to induce vitellogenin synthesis in 50% of the insects (6.7 ng 10R and 1710 ng 10S). In the JH-binding protein assay 10R-JH III had an affinity for the JH-binding protein (lipophorin) which was approximately 46 times higher than that of 10S-JH III.