Lipids from the marine worm Urechis unicinctus.

The lipid composition of four tissues, musculo-cutaneous, blood, internal organs, and gonads, from the marine worm Urechis unicinctus was studied. It was shown that the principal phospholipids (PL) in the studied tissues were phosphatidylcholine (PC) and phosphatidylethanolamine (PE). Depending on the tissue type, the fraction of PC was 31.8-42.6%; PE, 16.1-25.7% (of total PL). Blood contained a high percentage of lyso-PE (20.8%). The fatty-acid (FA) composition of the tissues consisted of C16, C18, C20, and C22 families with different degrees of unsaturation. Eicosapentaenoic acid (20:5) had the highest percentage in all tissues at 15.5-26.1%. Tissues with different functions such as musculo-cutaneous and gonads contained the same amounts of 20:5 FA, 26.1% (of total FA). The high content of polyunsaturated FA and, in particular, eicosapentaenoic FA in U. unicinctus confirmed that it was valuable as not only an energy source but also a source of PL and essential FA. [ABSTRACT FROM AUTHOR]