Structure and stereochemistry of a novel bioactive sphingolipid from a Calyx sp.

Bioassay-directed fractionation of a sponge of the genus Calyx using a yeas t bioassay for DNA-damaging agents yielded the novel sphingolipid calyxosid e (1) as the major bioactive constituent. The structure of 1 was assigned a s 1,3,26-trihydroxy-2,27-diaminooctacosan-18-one-1-beta -D-glucoside by H-1 - and C-13 NMR, DEPT, DQCOSY, HMQC, and HMBC spectra. The carbonyl group wa s located at C-18 by analysis of the EI-MS fragmentation of the amino deriv ative of its aglycone pentaacetate. Its absolute configuration was determin ed as 2S,3R,26S,27S by analysis of the H-1 NMR and CD spectra of its aglyco ne pentabenzoate. (C) 2001 Published by Elsevier Science Ltd.