Design, synthesis and biological activity of peptidomimetic analogs of insect allatostatins.

Allatostatins (ASTs) comprise a family of insect neuropeptides isolated from cockroaches and found to inhibit the production of juvenile hormone (JH) by the corpora allata (CA). For this reason, the ASTs can be regarded as possible IGR candidates for pest control. Six peptidomimetic analogs according to the C-terminal pentapeptide of ASTs were prepared by solid-phase organic synthetic methods in an attempt to obtain new simple substitution agents. Assays of inhibition of JH biosynthesis in vitro by corpora allata from the cockroach Diploptera punctata showed that the activity of analog I (IC(50): 0.09 μM) was more active than that of the C-terminal pentapeptide (Tyr-Xaa-Phe-Gly-Leu-NH(2), IC(50): 0.13 μM) it mimicked and the activity of the analog II (IC(50): 0.13 μM) proved roughly equivalent to the C-terminal pentapeptide. The results indicate that a new simple mimicry for Tyr-Xaa-Phe-Gly has been discovered; analog I may be a novel compound candidate for potential IGRs. This study will be useful for the design of new AST analogs for insect management.