Cell cycle analysis and stimulation of rat kangaroo cells (PtK 2 ) after pulse labeling.

out that the DL compounds 5, 8 were prepared from DL-aminobutyric acids. By analogy with the compounds 2 — 2 D and 3 3 D we expect that the biologically active components of the racemates were only their L-forms. All the compounds listed in Table I were subjected to additional topical or injection bioassays on a Pentatomid bug Graphosoma and on pupae of Tenebrio. No JH activity was recorded here and also in other orientation tests performed on Gryllus bimaculatus, Dermestes vulpinus, Drosophila melanogaster, etc. Evidently, all these compounds are highly specific, acting only on the insects of the family Pyrrhocoridae, similarly like the JH analogues of juvabione type 2. Contrary to the optical isomers of juvabione8, which all retain the JH activity2, the compounds we have described are aotive only when containing the natural L-amino acids. This phenomenon can perhaps be explained by a more rigid structure of the molecules containing amidic bonds. In order to obtain more information on the specificity and structure-activity relationships of these hormone analogues, we have prepared series of compounds in which other parts of the molecule have systematically been altered. The results will be published later.