Unusual 5-olefinic acids in the lipids of algae from Japanese waters.

Abstract

The fatty acid details of 2 species of Chlorophyta and Rhodophyta, and 5 species of Phaeophyta were elucidated by open-tubular gas-liquid chromatography. These algae contained a small amount of the unusual 5-olefinic acids such as 5-20:1, 5, 11-20:2, 5, 13-20:2, 5, 11, 14-20:3, and 5, 11, 14, 17-20:4 ( ?? 0.3%). The main 5-olefinic acids in sea urchin lipids such as 5-20:1, 5, 11-20:2 and 5, 13-20:2 were hardly seen in algal lipids. Therefore, it is assumed that these 5-olefinic acids in sea urchin lipids are not incorporated from algae as foods of sea urchin, but synthesized in sea urchins. The unusual 7-olefinic acids (7, 13-22:2 and 7, 15-22:2) formed by C2 elongation of 5, 11-20:2 and 5, 13-20:2 were also found in some algae slightly ( ?? 0.1%). Chlorophyta contained high levels of C16 (15.9-30.4%) and C18 (38.0-52.5%) polyunsaturated fatty acids (PUFA) and 22:5 (n-3) (2.0-6.0%). The major fatty acid components of Phaeophyta were C18 (15.4-44.0%) and C20 (11.5-33.5%) PUFA. Rhodophyta contained high levels of 20:4 (n-6) and 20:5 (n-3). The sums of these fatty acids in this class were more than 50%.