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A number of ethyl 4-(2-benzylalkyloxy)benzoates were prepared and their activity to induce precocious metamorphosis was evaluated in larvae of the silkworm, Bombyx mori, which was clearly recognized as a juvenile hormone (JH)-deficiency symptom. Ethyl 4-(2-benzylhexyloxy)benzoate (6) and its 2-benzylheptyloxy analog (7) were found to induce precocious metamorphosis at relatively low doses. Both enantiomers of 6 and 7 were prepared using a chiral auxiliary oxazolidinone. (S)-Enatiomers were more active than (R)-isomers at low doses of 0.1 and 1 mg, but at higher doses their activity was reversed. The activity of compound 6 could be fully counteracted by methoprene, a JH agonist, but not by the dietary administration of 20-hydroxyecdysone. The ester group was important in the ability to induce precocious metamorphosis. The (S)-enatiomer of 6 prolonged the duration of the instar and delayed the onset of cocoon spinning when applied to 5th instar larvae, suggesting that this compound might have JH-like activity as well as anti-JH activity.

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Some octopamine agonists were found to suppress in vitro biosynthesis of the calling pheromone of the Indian meal moth, Plodia interpunctella. Isolated pheromone-gland preparations incorporated sodium [14C]acetate at a linear rate for 3 h when incubated with the pheromone biosynthesis activating neuropeptide (PBAN). This incorporation was dependent on the dose of PBAN (up to 0.5 microM). Thin-layer chromatography of a pheromone-gland extract revealed quantitative incorporation of radioactivity into a product exhibiting the same mobility as (Z,E)-9,12-tetradecadienyl acetate, the main component of the calling pheromone of P interpunctella. Twenty-seven octopamine agonists were initially screened using a calling behaviour bioassay of female P interpunctella. Four derivatives with activity in the nanomolar range were identified which were, in order of decreasing pheromonostatic activity: 2-(2,6-diethylphenylimino)thiazolidine > 2-(2,6-diethylphenylimino)oxazolidine > 2-(2,6-dimethylphenylimino)thiazolidine > 2-(2-ethylphenylimino)oxazolidine. These compounds also showed in vitro inhibitory activity in intracellular de novo pheromone biosynthesis. The results of the present study indicate that these derivatives could provide useful information in the characterization and differentiation of octopaminergic receptor types and subtypes.

Juvenile hormone (JH) I, II and III in the hemolymph of the silkworm, Bombyx mori were quantified by liquid chromatography-mass spectrometry (LC-MS). JHs were treated with methanol and trifluoroacetic acid to convert into JH methoxyhydrines (JH-MHs). The key to the analytical condition for JH-MHs was the addition of 5 µM sodium acetate to the eluting solution. Each JH-MH was observed as the sodium adduct ion with good sensitivity. This improved method enabled the titration of JH I, II and III in hemolymph of the silkworm to be monitored from the 3rd instar through to the early pupal stage. A peak of JH I was observed immediately after ecdysis in the 3rd and 4th instar stages. The JH I titer sharply decreased on day 1 and reached the lowest level before ecdysis, but there was no peak at the beginning of the 5th stadium, and no apparent increase was observed until pupation.