Synthesis of Four Lysine-Linked Cereulide Analogues Showing Ionophoric Activity Towards Potassium Cations as Lead Compounds for Emetic Toxin-Detection by Immunoassays
作者:Minoru Isobe、Arthit Makarasen、Toshio Nishikawa
DOI:10.1055/s-0029-1216837
日期:2009.7
An improved total synthesis of the emetic toxin cereulide and the preparation of four lysine-linked cereulide analogues is described. The cereulide analogues are prepared by replacing one of the amino acid residues in cereulide with lysine. The cereulide analogues demonstrate ionophoric activity towards alkali metal ions and inorganic ammonium ions, and are currently being used to develop an enzyme-linked immunosorbent assay for cereulide.
Homocereulide, isolated from marine bacterium Bacillus cereus, is an analog of emetictoxincereulide. There is no report on its structure determination and involvement in B. cereus-associated food poisoning. Homocereulide is a cyclic dodecadepsipeptide composed of l-O-Val-l-Val-d-O-Leu-d-Ala and l-O-allo-Ile-d-Val-d-O-Leu-d-Ala. Here, we synthesized homocereulide using liquid phase fragment condensation
Hydrolysates of an emetic toxin cereulide were found in the broth of Bacillus cereus. The ester cleaved depsipeptides of cereulide were synthesized using liquid phase fragment condensation method starting from commercially available amino acids. The chemical structure of hydrolysates was verified tetradepsipeptide L-O-Val-L-Val-D-O-Leu-D-Ala and dodecadepsipeptide (D-O-Leu-D-Ala-L-O-Val-L-Val)(3) using LC-TOFMS. Quantitative analysis of cereulide in the broth revealed production of cereulide in the stationary phase and decomposition in the death phase. The increase in tetradepsipeptide continued after the stationary phase until decomposition occurred.