Omega n fatty acids
Omega n fatty acids are unsaturated fatty acids , with the n as a number indicating the position of the first double bond of the fatty acid; this is counted starting from the “ omega end”, the end of the molecule opposite the carboxy group . Alternatively, there is also a method of counting from the carboxy end as “delta n fatty acids”.
Nomenclature of unsaturated fatty acids
Unsaturated fatty acids have either an angled ( cis -fatty acids) or a linear ( trans -fatty acids ) hydrocarbon chain and a carboxy group (-COOH) at the end of the molecule. The unsaturated fatty acid residues in the triglycerides of (natural) oils and fats are almost exclusively cis -configured.
The carbon atom adjacent to the carboxy group is in the α position , the next in β position, etc. Since different fatty acids in nature can also have different chain lengths, the last carbon atom is uniformly referred to as “ω” (“ Omega ”), the last letter in the Greek alphabet , set.
Because the physiological properties of unsaturated fatty acids depend on the relative position of the first double bond to the omega end, these are referred to as “omega minus n”, or “omega-n” for short. There is a lipid name for all fatty acids , which is given in the form X: Y (ω − n) (with X = length of the C chain, Y = number of double bonds, n = position of the first double bond relative to the omega end) . For the omega-3 fatty acid alpha-linolenic acid, the lipid name is 18: 3 (ω − 3) , for the omega-6 fatty acid arachidonic acid 20: 4 (ω − 6) and for the omega-9 fatty acid oleic acid 18: 1 (ω − 9) .
Omega-3 fatty acids
The term "omega-3 fatty acids" stands for compounds in which the first double bond is located in the third position from the omega end. The α-linolenic acid is shown as a model compound :
| α-linolenic acid |
|---|
|
(9 Z , 12 Z , 15 Z ) -Octadeca-9,12,15-trienoic acid |
18: 3 (ω − 3) |
| Common name | Lipid name | Chemical name |
|---|---|---|
| Roughanic acid | 16: 3 (ω − 3) | (7 Z , 10 Z , 13 Z ) -hexadecatrienoic acid |
| Alpha linolenic acid | 18: 3 (ω − 3) | (9 Z , 12 Z , 15 Z ) octadecatrienoic acid |
| Stearidonic acid | 18: 4 (ω − 3) | (6 Z 9 Z , 12 Z , 15 Z ) -Octadecatetraensäure |
|
Eicosatrienoic acid (dihomolinolenic acid) |
20: 3 (ω − 3) | (11 Z , 14 Z , 17 Z ) -Eicosatrienoic acid |
| Eicosatetraenoic acid | 20: 4 (ω − 3) | (8 Z , 11 Z , 14 Z , 17 Z ) -Eicosatetraenoic acid |
| Eicosapentaenoic acid | 20: 5 (ω − 3) | (5 Z , 8 Z , 11 Z , 14 Z , 17 Z ) -Eicosapentaenoic acid |
| Heneicosapentaenoic acid | 21: 5 (ω − 3) | (6 Z , 9 Z , 12 Z , 15 Z , 18 Z ) -henicosapentaenoic acid |
| Docosapentaenoic acid | 22: 5 (ω − 3) | (7 Z , 10 Z , 13 Z , 16 Z , 19 Z ) -Docosapentaenoic acid |
| Docosahexaenoic acid | 22: 6 (ω − 3) | (4 Z , 7 Z , 10 Z , 13 Z , 16 Z , 19 Z ) -Docosahexaenoic acid |
|
Tetracosapentaenoic acid (scoliodonic acid ) |
24: 5 (ω − 3) | (9 Z , 12 Z , 15 Z , 18 Z , 21 Z ) -Tetracosapentaenoic acid |
|
Tetracosahexaenoic acid (nisic acid) |
24: 6 (ω − 3) | (6 Z , 9 Z , 12 Z , 15 Z , 18 Z , 21 Z ) -Tetracosahexaenoic acid |
The "lipid name" for α-linolenic acid is "18: 3 (ω-3)." Other important omega-3 fatty acids are eicosapentaenoic acid [ EPA , "20: 5 (ω-3)."] And docosahexaenoic acid [ DHA , " 22: 6 (ω-3). "].
Omega-6 fatty acids
The essential omega-6 fatty acids have - seen from the omega end (ω end) - the first double bond in the sixth position.
| Linoleic acid |
|---|
|
(9 Z , 12 Z ) -Octadeca-9,12-dienoic acid |
18: 2 (ω − 6) |
| Common name | Lipid name | Chemical name |
|---|---|---|
| Linoleic acid | 18: 2 (ω − 6) | (9 Z , 12 Z ) octadecadienoic acid |
| Gamma linolenic acid | 18: 3 (ω − 6) | (6 Z 9 Z , 12 Z ) -octadecatrienoic acid |
| Calendulic acid | 18: 3 (ω − 6) | (8 E , 10 E , 12 Z ) -Octadecatrienoic acid |
| Eicosadienoic acid | 20: 2 (ω − 6) | (11 Z , 14 Z ) -eicosadienoic acid |
| Dihomogammalinolenic acid | 20: 3 (ω − 6) | (8 Z , 11 Z , 14 Z ) -Eicosatrienoic acid |
| Arachidonic acid | 20: 4 (ω − 6) | (5 Z , 8 Z , 11 Z , 14 Z ) -Eicosatetraenoic acid |
| Docosadienoic acid | 22: 2 (ω − 6) | (13 Z , 16 Z ) -Docosadienoic acid |
| Docosatetraenoic acid | 22: 4 (ω − 6) | (7 Z , 10 Z , 13 Z , 16 Z ) -Docosatetraenoic acid |
|
Docosapentaenoic acid (osbondic acid) |
22: 5 (ω − 6) | (4 Z , 7 Z , 10 Z , 13 Z , 16 Z ) -Docosapentaenoic acid |
| Tetracosatetraenoic acid | 24: 4 (ω − 6) | (9 Z , 12 Z , 15 Z , 18 Z ) -Tetracosatetraenoic acid |
| Tetracosapentaenoic acid | 24: 5 (ω − 6) | (6 Z , 9 Z , 12 Z , 15 Z , 18 Z ) -Tetracosapentaenoic acid |
Omega-9 fatty acids
In omega-9 fatty acids , the first double bond is in the ninth position from the omega end.
| Oleic acid |
|---|
|
( 9Z ) -Octadec-9-enoic acid |
18: 1 (ω − 9) |
| Common name | Lipid name | Chemical name |
|---|---|---|
| Oleic acid | 18: 1 (ω − 9) | (9 Z ) octadecenoic acid |
| Gondo acid | 20: 1 (ω − 9) | (11 Z ) -eicosenoic acid |
| Mead's acid | 20: 3 (ω − 9) | (5 Z , 8 Z , 11 Z ) -Eicosatrienoic acid |
| Erucic acid | 22: 1 (ω − 9) | (13 Z ) -docosenoic acid |
| Nervonic acid | 24: 1 (ω − 9) | (15 Z ) tetracosenoic acid |
| Ximenic acid | 26: 1-delta-17c (ω − 9) | (17 Z ) -17-hexacosenoic acid |
literature
- H.-D. Belitz, W. Grosch, P. Schieberle: Food chemistry . Springer, Berlin / Heidelberg 2008, ISBN 978-3-540-73201-3 , Unsaturated fatty acids, p. 165 , doi : 10.1007 / 978-3-540-73202-0_4 .