Positional distribution of Δ5-olefinic acids in triacylglycerols from Torreya grandis seed oil: Isolation and purification of sciadonic acid

In recent years, in concern for human health, increasing attention was focused on sciadonic acid (SA), a unique Δ5-olefinic acid. Torreya grandis ( T. grandis ), a large, evergreen coniferous tree, whose seed yields rare and is known for a high level of SA. Triacylglycerols (TAGs) from the seeds of four different T. grandis varieties (Yuanfei, Xifei, Xiangyafei, and Zhimafei), were analyzed with respect to fatty acid profiles and positional distributions. The results indicated that SA represented the majority of the Δ5-olefinic acids in T. grandis seed oil. Irrespective of the variety, SA was naturally abundant at the sn-3 position of TAGs where they accounted for approximately 7.52%–12.00%. Based on this specific characteristic of Δ5-olefinic acids, T. grandis seed oil was subjected to a two-step enrichment process involving specific lipase-catalyzed ethanolysis and urea complexing. The content of SA in the fatty acid ethyl ester was increased to 80.14% from an initial value of 9.95%. These results suggested that the developed enrichment strategy was simple and effective in concentrating SA, and had the potential for commercial application.