Destruxin analogs: variations of the alpha-hydroxy acid side chain

This work describes the synthesis of three destruxin E cyclodepsipeptidic analogs. These compounds have an identical amino acid sequence but differ by the nature of the hydroxy acid residue with is 2-hydroxy-3-phenylpropionic (Hpp), 2-hydroxy-5-trimethylsilyl-4-pentynoic (Hpy-TMS) and 2-hydroxy-4-pentynoic (Hpy) acid, respectively. The insecticidal properties on the Galleria mellonella larvae (paralysis and lethal effect) of these analogs are presented in comparison with the natural destruxin E. All these compounds have toxic effects, the most potent being Hpy that induces the same effect as destruxin E.