Sagittamides A and B. Polyacetoxy long-chain acyl amino acids from a didemnid ascidian.

[structure: see text]. An unidentified tunicate from Pohnpei, Micronesia, yielded sagittamides A and B-compounds comprising a long-chain C26 dicarboxylic acid that acylates terminal L-valine and L-ornithine groups. The structures, which contain an unprecedented internal O-hexacetyl-1,2,3,4,5,6-hexaol moiety, were determined by combined spectroscopic analysis including mass spectrometry and 1D and 2D NMR and chemical degradation. The partial absolute stereochemistry of the new compounds was addressed by Marfey's analysis.