An antifungal cyclodepsipeptide, cyclolithistide A, from the sponge Theonella swinhoei

A novel antifungal cyclic depsipeptide, cyclolithistide A (1), was isolated from a marine sponge, Theonella swinhoei. The structure of cyclolithistide A, which contains the unique amino acids 4-amino-3, 5-dihydroxyhexanoic ac id, formyl-leucine, and chloroisoleucine, was elucidated through a combinat ion of spectroscopic techniques. Thirteen additional specimens of T. swinho ei and three of Theonella conica were examined in this study. Many containe d the two cyclic peptides, motuporin (2) and theonellapeptolide Id (3), as major components, but none of these were a source of 1. The rationale behin d this study and some additional aspects of these unusual results are prese nted.