Insect neuropeptide proctolin and its analogues. An overview of the present literature.

In the present paper, the literature describing synthetic, biological and conformational studies on the insect neuropeptide proctolin (H-Arg-Tyr-Leu-Pro-Thr-OH) and its analogues is summarized. The paper covers proctolin and its 80 analogues modified in positions 1-5, a cycloanalogue and analogues with a truncated or elongated peptide chain. These peptides were bioassayed by different methods, e.g. studies of myotropic activities in several insect species in vitro and behaviour in rats in vivo. Based on these data structure-activity relationships are discussed.