INHIBITION OF JUVENILE-HORMONE BIOSYNTHESIS AND METHYL FARNESOATE EPOXIDASE ACTIVITY BY 1,5-DISUBSTITUTED IMIDAZOLES IN THE COCKROACH, DIPLOPTERA-PUNCTATA

Seventeen substituted imidazoles were tested as inhibitors of juvenile hormone (JH) III synthesis by cockroach corpora allata in an in-vitro radiochemical assay. Most of these 1,5-disubstituted imidazoles were highly potent, with IC,, values of less than 100 nM. The compounds dif fered in their ability to cause an accumulation of the precursor methy l farnesoate in the glands. Four of the imidazoles were tested by topi cal application to previtellogenic adult females, and ail caused a sig nificant inhibition of JH synthesis and an accumulation of intraglandu lar methyl farnesoate for at least three days after treatment. Methyl farnesoate epoxidase activity of homogenates of corpora allata was inh ibited by the compounds TH-14 and TH-27. This P450-dependent epoxidase activity was inhibited at less than 10 nM. The results show that the 1,5-disubstituted imidazoles are powerful inhibitors of the last step of juvenile synthesis in this cockroach.