Ceramides from the Taiwan Red Alga Ceratodictyon Spongiosum and Symbiotic Sponge Sigmadocia Symbiotica

The structure of a mixture of ceramides ( 1 ) de rived from 2‐amino‐4(E)‐alkene‐1,3‐diol sphingenines with C₂₂, C₂₃, and C₂₄ saturated fatty acid residues from red alga Ceratodictyon spongiosum ZANARDINI (Rhodymeniaceae) containing the symbiotic sponge Sigmadocia symbiotica has been elucidated on the basis of spectroscopic and chemical evidence. In addition, one new sterol, n‐nonadecanoic acid 24‐ methylenecholesteryl ester ( 2 ), and six known sterols were also isolated from the marine organisms.