Purification of stearidonic acid (18:4(n-3)) and hexadecatetraenoic acid (16:4(n-3)) from algal fatty acid with lipase and medium pressure liquid chromatography.

Stearidonic acid (18:4(n-3)) and hexadecatetraenoic acid (16:4(n-3)) are included in some edible marine algae such as Undaria pinnatifida and Ulva pertusa with relatively high compositions (up to 40%) of total fatty acids. In order to prepare 16:4(n-3) and 18:4(n-3) enriched fatty acid concentrates, we screened for a suitable lipase which concentrates these acids by the removal of other fatty acids in the selective esterification reaction reported by Shimada et al. (Shimada et al. (1997), J. Am. Oil Chem. Soc., 74, 1465-1470). In combination with the lipase reaction and reversed-phase medium pressure liquid chromatography, we purified 18:4(n-3) and 16:4(n-3) to more than 95% purity.

Effect of tetracosahexaenoic acid on the content and release of histamine, and eicosanoid production in MC/9 mouse mast cell.

6,9,12,15,18,21-Tetracosahexaenoic acid (24:6n-3) was isolated from a brittle star, Ophiura sarsi Lütken, at >95% purity to evaluate its physiological functions. The effects of 24:6n-3 on the production of leukotriene (LT)-related compounds such as LTB4, LTC4 and 5-hydroxyeicosatetraenoic acid, and the accumulation and release of histamine in an MC/9 mouse mast cell line were studied. We found that 24:6n-3 could inhibit the antigen-stimulated production of LT-related compounds as well as other n-3 polyunsaturated fatty acids (PUFA) such as eicosapentaenoic acid (20:5n-3) and docosahexaenoic acid (22:6n-3), which are major n-3 PUFA in fish oils; 24:6n-3 was also shown to reduce the histamine content in MC/9 cells at 25 microM (27% reduction from the control), and the effect was diminished with increase of the fatty acid concentration (up to 100 microM). These two n-3 PUFA, 20:5n-3 and 22:6n-3, also reduced the histamine content (16 and 20% reduction at 25 microM, respectively), whereas arachidonic acid (20:4n-6) increased it (18% increase at 25 microM). Spontaneous- and antigen-induced release of histamine was not influenced with these PUFA (at 25 microM). Ionophore-stimulated release of histamine was suppressed by the PUFA (13, 9, 15, and 11% reduction with 20:4n-6, 20:5n-3, 22:6n-3, and 24:6n-3, respectively). The patterns of the effects of 24:6n-3 on the synthesis of eicosanoids and histamine content were more similar to those of 22:6n-3 than 20:5n-3. From these results, 24:6n-3 can be expected to have anti-inflammatory activity and antiallergic activities similar to those of 22:6n-3.

Inhibition of icosanoid production in MC/9 mouse mast cells by n-3 polyunsaturated fatty acids isolated from edible marine algae.

The effects of two polyunsaturated fatty acids, 18:4n-3 and 16:4n-3 purified from the marine algae, Undaria pinnatifida and Ulva pertusa, on icosanoid production in MC/9 mouse mast cells were assessed. Both fatty acids suppressed the production of leukotriene B4 (LTB4), leukotriene C4 (LTC4), and 5-hydroxyeicosatetraenoic acid (5-HETE). The order of the suppressive activity for the two marine algae-derived fatty acids and three other common polyunsaturated fatty acids was as follows; 22:6n-3 = 18:4n-3 = 18:3n-3 > 20:5n-3 = 16:4n-3 for LTB4; 22:6n-3 = 18:4n-3 = 18:3n-3 > 16:4n-3 > 20:5n-3 (no suppression) for LTC4; 22:6n-3 = 18:4n-3 > 18:3n-3 > 20:5n-3 = 16:4n-3 for 5-HETE.