Inhibitors of juvenile hormone biosynthesis in corpora allata of the cockroach Periplaneta americana (L.) in vitro

The spontaneous biosynthesis of methyl (2E,6E)‐(10R)‐10,11‐epoxy‐3,7,11‐trimethyldodeca‐2,6‐dienoate (juvenile hormone III; JH III) in excised corpora allata of Periplaneta americana was inhibited by a number of synthetic prop‐2‐ynyl ethers and 1,3‐benzodioxole derivatives. One structurally diverse group of compounds inhibited only the final biosynthetic enzyme methyl farnesoate epoxidase (EC.1.14.14.–) at low to moderate concentrations, but at higher concentrations, also inhibited methyl farnesoate (MF) formation, causing an accumulation of MF in the concentration range 10 to 100 μM. For a second, more limited, group of compounds, there was close congruence between the inhibition of JH III biosynthesis and that of total ester (MF plus JH III) biosynthesis over their effective inhibitory concentration ranges. In contrast to the first group, there was no accumulation of MF and these compounds evidently inhibited JH III biosynthesis, at the level of either farnesoic acid esterification by O‐methyl transferase (EC.2.1.1.–), or at an earlier step in the biosynthetic pathway that remains to be elucidated.