Polyazamacrolides from ladybird beetles: Ring-size selective oligomerization

Abstract

The pupal defensive secretion of the 24-pointed ladybird beetle, Subcoccinella vigintiquatuorpunctata, consists of a mixture of macrocyclic polyamines, dominated by the three dimeric, 30-membered macrocycles 11-13, derived from the two building blocks 11-(2-hydoxyethylamino)-5-tetradecenoic acid (9) and 11-(2-hydoxyethylamino)-5,8-tetradecadienoic acid (10). Smaller amounts of the four possible cyclic trimers of 9 and 10 were also detected, corresponding to 45-membered macrocycles. Structural assignments were based on NMR-spectroscopic investigations and HPLC-MS analyses. In addition, the all-S absolute configuration of the S. vigintiquatuorpunctata macrocycles was determined by comparison of derivatives of the natural material with enantiomerically pure synthetic samples. Comparing this alkaloid mixture with that of the pupal defensive secretion in related ladybird beetle species indicates that the degree of oligomerization of the 2-hydroxyethylamino carboxylic acid building blocks can be carefully controlled by the insects.

Mayolenes: Labile defensive lipids from the glandular hairs of a caterpillar ( Pieris rapae )

“…They are of less frequent occurrence in insects, but the chemistry of the secretion of insectan hairs, to the extent that it is known, can be of interest. Thus, for instance, the pupal hairs of certain coccinellid beetles have been shown to produce, in one species, a series of azamacrolides, and in others a combinatorial mixture of macrocyclic polyamines (15)(16)(17). The present discovery of yet another novel group of secondary products from the glandular hairs of an insect suggests that the study of such defensive materials can be rewarding.…”

Natural Enemies of Ladybird Beetles

“…Refl ex bleeding is commonly used by adults of many ladybird species and by larvae and/or pupae of some species, but in the latter cases, the fl uid is usually released from pores in the dorsal body surface (Holloway et al 1991, Daloze et al 1995. The pupae of some Epilachninae are known to exude the droplets of defensive fl uid by specialized, glandular hairs (Schroeder et al 1998 ). In adult ladybirds, refl ex bleeding is often associated with thanatosis (Daloze et al 1995, Ceryngier & Hodek 1996.…”

The 2013 Benjamin Franklin Medal in Chemistry presented to Jerrold Meinwald, Ph.D.

“…None were detected by GC-MS. However, when an NMR analysis of the crude secretion was conducted a number of polyazamacrolides, such as 29, were identified [30][31][32][33]. Following the preparation of synthetic samples, these molecules were shown to repel ants [34].…”