Isolation and structure of three new ceramides from the starfish Acanthaster planci

Three new phytosphingosine-type ceramides, AC-1-6, AC-1-10 and AC-1-11, were isolated from the ceramide molecular species AC-1, obtained from the less polar fraction of the CHCl₃/MeOH extract of the starfish Acanthaster planci. The structures of these ceramides were determined on the basis of chemical and spectroscopic evidence as (2S,2′ R,3S,4R,9Z)-2-(2-hydroxyhexadecanoylamino)-9-docosene-1,3,4-triol (AC-1-6), (2S,2′ R,3S,4R,)-2-(2-hydroxytricosanoylamino)hexadecane-1,3,4-triol (AC-1-10) and (2S,2′ R,3S,4R,)-2(2-hydroxytetracosanoylamino)hexadecane-1,3,4-triol (AC-1-11). Positive ion FABMS/MS of each ceramide gave important information for their structure elucidation. Mass spectrometry of the dimethyl disulfide derivatives of ceramide was also useful for the determination of the double bond position in the long-chain base.