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 acid, formyl-leucine, and chloroisoleucine, was elucidated through a combination of spectroscopic techniques. Thirteen additional specimens of T. swinhoei and three of Theonella conica were examined in this study. Many contained the two cyclic peptides, motuporin ( 2 ) and theonellapeptolide 1d ( 3 ), as major components, but none of these were a source of 1 . The rationale behind this study and some additional aspects of these unusual results are presented.