Docosapentaenoic acid

Docosapentaenoic acid (DPA) designates any straight chain 22:5 fatty acid, that is a straight chain open chain type of polyunsaturated fatty acid (PUFA) which contains 22 carbons and 5 double bonds. DPA is primarily used to designate two isomers, all-cis-4,7,10,13,16-docosapentaenoic acid (i.e. 4Z,7Z,10Z,13Z,16Z-docosapentaenoic acid) and all-cis-7,10,13,16,19-docosapentaenoic acid (i.e. 7Z,10Z,13Z,16Z,19Z-docosapentaenoic acid). They are also commonly termed n-6 DPA and n-3 DPA, respectively; these designations describes the position of the double bond being 6 or 3 carbons closest to the (omega) carbon at the methyl end of the molecule and is based on the biologically important difference that n-6 and n-3 PUFA are separate PUFA classes, i.e. the omega-6 fatty acids and omega-3 fatty acids, respectively. Mammals, including humans, can not interconvert these two classes and therefore must obtain dietary essential PUFA fatty acids from both classes in order to maintain normal health (see essential fatty acids).[1][2]

Isomers
For nomenclature, see essential fatty acid § nomenclature.

all-cis-4,7,10,13,16-docosapentaenoic acid (osbond acid)
The chemical structure of osbond acid showing physiological numbering (red) and chemical numbering (blue) conventions.

n-6 DPA is an ω-6 fatty acid with the trivial name osbond acid. It is formed by the stepwise elongation and desaturation of arachidonic acid i.e. 5Z,8Z,11Z,14Z-eicosatetraenoic acid (5,8,11,14-20:4n-6) to the 24 carbon PUFA intermediate (i.e. 6,9,12,15,18:24-5n-6) and the retro-conversion of this intermediate to DPAn-6 as follows:[3]

all-cis-7,10,13,16,19-docosapentaenoic acid (clupanodonic acid)
The chemical structure of clupanodonic acid showing physiological numbering (red) and chemical numbering (blue) conventions.

n-3 DPA is an n-3 fatty acid with the trivial name clupanodonic acid. It is an intermediary between eicosapentaenoic acid (EPA, 5,8,11,14,17-20:5n-3) and docosahexaenoic acid (DHA, 22:6 ω-3) in the following stepwise pathway in which DPAn-3 is a precursor to DHA (6,9,12,15,18,21:24:6n-3) and the final product, 4,7,10,13,16,19-22:6n-3, can be retro-converted to DPAn-3:[1][4]

Mammalian cells, including human cells, metabolize DPAn-3 to an array of products that are members of the specialized proresolving mediators class of PUFA metabolites. These metabolites include seven resolvins Ds (RvT1, RvT2, RvT3, RvT4, RvD1n-3, RvD2n-3, and RvD5n-3; see specialized proresolving mediators#n-3 DPA-derived resolvins and Resolvin); two protectins (PD1n-3 and PD2n-3; see specialized proresolving mediators#n-3 DPA-derived protectins/neuroprotectins and neuroprotectin); and three maresins (MaR1n-3, MaR2n-3,and MaR3n-3l see specialized proresolving mediators#n-3 DPA-derived maresins and maresin.

Nutrition

Docosapentaenoic acid (DPA) is an n-3 fatty acid that is structurally similar to eicosapentaenoic acid (EPA) with the same number of double bonds, but two more carbon chain units.[5]

Dietary sources

These are the top five sources for DPA according to the USDA Agricultural Research Service:[6]

  1. Fish oil, menhaden 0.668g in 1 tbsp. (13.6g)
  2. Fish oil, salmon 0.407g in 1 tbsp. (13.6g)
  3. Salmon, red (sockeye), filets with skin, smoked (Alaska Native) 0.335g in 1 filet (108g)
  4. Fish, salmon, Atlantic, farmed, raw 0.334g in 3 oz (85g)
  5. Beef, variety meats and by-products, brain, cooked, simmered 0.326g in 3oz (85g)

Seal meat and human breast milk are rich in DPA.[5]

Functions

Clupanodonic acid, an omega-3 fatty acid, along with its metabolite DHA and other long chain omega-3 fatty acids, is under study to determine properties of omega-3 fats in humans, such as in inflammation mechanisms.[7]

See also

References
  1. Edwards IJ, O'Flaherty JT (2008). "Omega-3 Fatty Acids and PPARgamma in Cancer". PPAR Research. 2008: 358052. doi:10.1155/2008/358052. PMC 2526161. PMID 18769551.
  2. Spector AA, Kim HY (2015). "Discovery of essential fatty acids". Journal of Lipid Research. 56 (1): 11–21. doi:10.1194/jlr.R055095. PMC 4274059. PMID 25339684.
  3. Sprecher H (2000). "Metabolism of highly unsaturated n-3 and n-6 fatty acids". Biochimica et Biophysica Acta (BBA) - Molecular and Cell Biology of Lipids. 1486 (2–3): 219–31. doi:10.1016/s1388-1981(00)00077-9. PMID 10903473.
  4. Spector AA (1999). "ssentiality of fatty acids". Lipids. 34 Suppl: S1–3. doi:10.1007/bf02562220. PMID 10419080. S2CID 4061017.
  5. Yazdi, PG (Nov 2013). "A review of the biologic and pharmacologic role of docosapentaenoic acid n-3". F1000Res. 2: 256. doi:10.12688/f1000research.2-256.v2. PMC 4162505. PMID 25232466.
  6. "DPA Nutrient List." National Nutrient Database for Standard Reference Release 27.
  7. Dalli, J; Chiang, N; Serhan, C. N. (2015). "Elucidation of novel 13-series resolvins that increase with atorvastatin and clear infections" (PDF). Nature Medicine. 21 (9): 1071–5. doi:10.1038/nm.3911. PMC 4560998. PMID 26236990.
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