Heneicosapentaenoic acid is 21:5 n-3 fatty acid found in trace amounts in green alga B. pennata and in fish oils. The chemical composition resembles eicosapentaenoic acid except an elongated with one carbon on carbon on carboxyl end which place the first double bond in the Δ6 position. HPA is used to study influence of the position of double bonds in ω-3 fatty acids. It assimilates into phospholipids and into triacylglycerol in vivo having same efficiency as EPA and docosahexaenoic acid & exhibit strong inhibition of arachidonic acid synthesis from linoleic acid. It is a poor substrate for prostaglandin H synthase and 5-lipoxygenase but retains ability to rapidly inactivate PGHS.
Food Sources
| Food name | Weight (g) | Heneicosapentaenoic acid (g) |
| Red (sockeye) salmon | 108 | 0.027 |
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