Omega-7 fatty acid

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Omega-7 fatty acids are a class of unsaturated fatty acids in which the site of unsaturation is seven carbon atoms from the end of the carbon chain. The two most common omega-7 fatty acids in nature are palmitoleic acid and vaccenic acid. [1] They are widely used in cosmetics due to their moisturizing properties. Omega-7 fats are not essential fatty acids in humans as they can be made endogenously. Diets rich in omega-7 fatty acids have been shown to have beneficial health effects, such as increasing levels of HDL cholesterol and lowering levels of LDL cholesterol.

Contents

Rich sources include macadamia nut oil and sea buckthorn (berry) oil in the form of palmitoleic acid, while dairy products are the primary sources of vaccenic acid and rumenic acid. [2] A lesser but useful source of palmitoleic acid is avocado fruit (25,000ppm). [3]

The monounsaturated omega-7 fatty acids have the general chemical structure CH3-(CH2)5-CH=CH-(CH2)n-CO2H.

Common nameLipid nameChemical name
none12:1 (n−7)5-Dodecenoic acid
none14:1 (n−7)7-Tetradecenoic acid
Palmitoleic acid 16:1 (n−7)9-Hexadecenoic acid
Vaccenic acid 18:1 (n−7)11-Octadecenoic acid
Rumenic acid 18:2 (n−7)Octadeca-9,11-dienoic acid
Paullinic acid 20:1 (n−7)13-Eicosenoic acid
none22:1 (n−7)15-Docosenoic acid
none24:1 (n−7)17-Tetracosenoic acid

Metabolism

16- and 18-carbon omega-7 unsaturated fatty acids are known to be converted into 18- or 20-carbon highly unsaturated fatty acids in the body by nonselective desaturating enzymes. [4]  The same enzymes also act on omega-3, omega-6, and omega-9 fatty acids.  As a result, while proportions of individual highly unsaturated fatty acids may vary greatly in different tissue types due to factors such as diet, the overall concentration of highly unsaturated fatty acids is kept stable in a living organism.  These individual concentrations are highly influential in determining what fatty acids will be used by a given tissue type in phospholipid synthesis such as that required for the maintenance of the cellular membrane. [4]

Research

Diabetes

Omega-7 fatty acids, especially palmitoleic acid, have been shown in vitro to decrease glucose-sensitive apoptosis in beta cells in the pancreas, a condition associated with diabetes. [5] [6]   In adult organisms, new beta cells are most commonly the result of replication rather than from direct stem cell differentiation, meaning that preventing apoptosis of beta cells is crucial for maintaining a stable population of beta cells.  The cytoprotective effect of omega-7 fatty acids makes them a candidate for diabetes treatment. [5]

Production

In cows

Dairy products are one of the primary sources of dietary omega-7 fatty acids.  However, the production of omega-7 fatty acids in cows is heavily diet-dependent. [7]   Specifically, a reduction in the proportion of herbage consumed by a cow is correlated with a significant decrease in the omega-7 fatty acid content of the cow's milk. Rumenic and vaccenic acid concentrations declined significantly within one week of removing herbage from the cow's diet, suggesting that modern dairy farming methods may lead to decreases in beneficial fatty acid content of dairy products. [7]

Algal extraction

Traditional sources of omega-7 fatty acids such as macadamia nuts have proved expensive on the industrial scale, prompting the discovery of new omega-7 rich sources such as algae.  Alterations to algal growing conditions such as carbon dioxide or dipotassium phosphate enrichment have been shown to potential bias algal biosynthesis towards lipids. [8]   Up to 90% of their dry weight may be harvested as lipids. In this process, raw algae is dewatered to yield algal oil.  Algal oil gets degummed, typically via washing with acid, to removing polar lipids and metals.  Degummed algal oil is then transesterified and purified to yield a mixture of omega-7 esters and eicosapentaenoic acids, which can be hydrodeoxygenated to form algae jet fuel and algae green diesel, respectively. These products are then crystallized and separated to yield the desired omega-7 fatty acid [ citation needed ].

See also

Related Research Articles

<span class="mw-page-title-main">Fatty acid</span> Carboxylic acid

In chemistry, particularly in biochemistry, a fatty acid is a carboxylic acid with an aliphatic chain, which is either saturated or unsaturated. Most naturally occurring fatty acids have an unbranched chain of an even number of carbon atoms, from 4 to 28. Fatty acids are a major component of the lipids in some species such as microalgae but in some other organisms are not found in their standalone form, but instead exist as three main classes of esters: triglycerides, phospholipids, and cholesteryl esters. In any of these forms, fatty acids are both important dietary sources of fuel for animals and important structural components for cells.

<span class="mw-page-title-main">Fat</span> Esters of fatty acid or triglycerides

In nutrition, biology, and chemistry, fat usually means any ester of fatty acids, or a mixture of such compounds, most commonly those that occur in living beings or in food.

Omega−3 fatty acids, also called Omega−3 oils, ω−3 fatty acids or n−3 fatty acids, are polyunsaturated fatty acids (PUFAs) characterized by the presence of a double bond, three atoms away from the terminal methyl group in their chemical structure. They are widely distributed in nature, being important constituents of animal lipid metabolism, and they play an important role in the human diet and in human physiology. The three types of omega−3 fatty acids involved in human physiology are α-linolenic acid (ALA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). ALA can be found in plants, while DHA and EPA are found in algae and fish. Marine algae and phytoplankton are primary sources of omega−3 fatty acids. DHA and EPA accumulate in fish that eat these algae. Common sources of plant oils containing ALA include walnuts, edible seeds, and flaxseeds as well as hempseed oil, while sources of EPA and DHA include fish and fish oils, and algae oil.

Essential fatty acids, or EFAs, are fatty acids that humans and other animals must ingest because the body requires them for good health, but cannot synthesize them.

An unsaturated fat is a fat or fatty acid in which there is at least one double bond within the fatty acid chain. A fatty acid chain is monounsaturated if it contains one double bond, and polyunsaturated if it contains more than one double bond.

<span class="mw-page-title-main">Palmitic acid</span> Chemical compound

Palmitic acid is a fatty acid with a 16-carbon chain. It is the most common saturated fatty acid found in animals, plants and microorganisms. Its chemical formula is CH3(CH2)14COOH, and its C:D ratio is 16:0. It is a major component of palm oil from the fruit of Elaeis guineensis, making up to 44% of total fats. Meats, cheeses, butter, and other dairy products also contain palmitic acid, amounting to 50–60% of total fats.

In biochemistry and nutrition, a monounsaturated fat is a fat that contains a monounsaturated fatty acid (MUFA), a subclass of fatty acid characterized by having a double bond in the fatty acid chain with all of the remaining carbon atoms being single-bonded. By contrast, polyunsaturated fatty acids (PUFAs) have more than one double bond.

<span class="mw-page-title-main">Docosahexaenoic acid</span> Chemical compound

Docosahexaenoic acid (DHA) is an omega-3 fatty acid that is a primary structural component of the human brain, cerebral cortex, skin, and retina. It is given the fatty acid notation 22:6(n-3). It can be synthesized from alpha-linolenic acid or obtained directly from maternal milk, fatty fish, fish oil, or algae oil. The consumption of DHA contributes to numerous physiological benefits, including cognition. As the primary structural component of nerve cells in the brain, the function of DHA is to support neuronal conduction and to allow optimal function of neuronal membrane proteins.

<span class="mw-page-title-main">Palmitoleic acid</span> Chemical compound

Palmitoleic acid, or (9Z)-hexadec-9-enoic acid, is an omega-7 monounsaturated fatty acid (16:1n-7) with the formula CH3(CH2)5CH=CH(CH2)7COOH. It is a rare component of fats. It is a common constituent of the glycerides of human adipose tissue. It is present in all tissues but, in general, found in higher concentrations in the liver.

Omega-9 fatty acids are a family of unsaturated fatty acids which have in common a final carbon–carbon double bond in the omega−9 position; that is, the ninth bond from the methyl end of the fatty acid.

<span class="mw-page-title-main">Polyunsaturated fat</span> Type of fatty acid defined by molecular bonds

In biochemistry and nutrition, a polyunsaturated fat is a fat that contains a polyunsaturated fatty acid, which is a subclass of fatty acid characterized by a backbone with two or more carbon–carbon double bonds. Some polyunsaturated fatty acids are essentials. Polyunsaturated fatty acids are precursors to and are derived from polyunsaturated fats, which include drying oils.

Fatty acid desaturases are a family of enzymes that convert saturated fatty acids into unsaturated fatty acids and polyunsaturated fatty acids. For the common fatty acids of the C18 variety, desaturases convert stearic acid into oleic acid. Other desaturases convert oleic acid into linolenic acid, which is the precursor to alpha-linolenic acid, gamma-linolenic acid, and eicosatrienoic acid.

A wax ester (WE) is an ester of a fatty acid and a fatty alcohol. Wax esters are the main components of three commercially important waxes: carnauba wax, candelilla wax, and beeswax.

Vaccenic acid is a naturally occurring trans fatty acid and an omega-7 fatty acid. It is the predominant kind of trans-fatty acid found in human milk, in the fat of ruminants, and in dairy products such as milk, butter, and yogurt. Trans fat in human milk may depend on trans fat content in food.

In biochemistry, fatty acid synthesis is the creation of fatty acids from acetyl-CoA and NADPH through the action of enzymes called fatty acid synthases. This process takes place in the cytoplasm of the cell. Most of the acetyl-CoA which is converted into fatty acids is derived from carbohydrates via the glycolytic pathway. The glycolytic pathway also provides the glycerol with which three fatty acids can combine to form triglycerides, the final product of the lipogenic process. When only two fatty acids combine with glycerol and the third alcohol group is phosphorylated with a group such as phosphatidylcholine, a phospholipid is formed. Phospholipids form the bulk of the lipid bilayers that make up cell membranes and surrounds the organelles within the cells. In addition to cytosolic fatty acid synthesis, there is also mitochondrial fatty acid synthesis (mtFASII), in which malonyl-CoA is formed from malonic acid with the help of malonyl-CoA synthetase (ACSF3), which then becomes the final product octanoyl-ACP (C8) via further intermediate steps.

<span class="mw-page-title-main">Nervonic acid</span> Chemical compound

Nervonic acid is a fatty acid. It is a monounsaturated analog of lignoceric acid (24:0). It is also known as selacholeic acid and cis-15-tetracosenoic acid. Its name derives from the Latin word nervus, meaning nerve or sinew.

<i>Nannochloropsis</i> Genus of algae

Nannochloropsis is a genus of algae comprising six known species. The genus in the current taxonomic classification was first termed by Hibberd (1981). The species have mostly been known from the marine environment but also occur in fresh and brackish water. All of the species are small, nonmotile spheres which do not express any distinct morphological features that can be distinguished by either light or electron microscopy. The characterisation is mostly done by rbcL gene and 18S rRNA sequence analysis.

<i>Nannochloropsis</i> and biofuels

Nannochloropsis is a genus of alga within the heterokont line of eukaryotes, that is being investigated for biofuel production. One marine Nannochloropsis species has been shown to be suitable for algal biofuel production due to its ease of growth and high oil content, mainly unsaturated fatty acids and a significant percentage of palmitic acid. It also contains enough unsaturated fatty acid linolenic acid and polyunsaturated acid for a quality biodiesel.

Only two essential fatty acids are known to be essential for humans: alpha-linolenic acid and linoleic acid. The biological effects of the ω-3 and ω-6 fatty acids are mediated by their mutual interactions. Closely related, these fatty acids act as competing substrates for the same enzymes. The biological effects of the ω-3 and ω-6 fatty acids are largely mediated by essential fatty acid interactions. The proportion of omega-3 to omega-6 fatty acids in a diet may have metabolic consequences. Unlike omega-3 fatty acids and omega-6 fatty acids, omega-9 fatty acids are not classed as essential fatty acids because they can be created by the human body from monounsaturated and saturated fatty acids, and are therefore not essential in the diet.

References

  1. ↑ Mukherjee KD, Kiewitt I (October 1980). "Formation of (n-9) and (n-7) cis-monounsaturated fatty acids in seeds of higher plants". Planta. 149 (5): 461–3. Bibcode:1980Plant.149..461M. doi:10.1007/BF00385748. PMID   24306473. S2CID   22892828.
  2. ↑ Destaillats F, Buyukpamukcu E, Golay PA, Dionisi F, Giuffrida F (February 2005). "Vaccenic and rumenic acids, a distinct feature of ruminant fats". Journal of Dairy Science. 88 (2): 449. doi: 10.3168/jds.S0022-0302(05)72705-3 . PMID   15653508.
  3. ↑ Duke, James A. (1992). Handbook of phytochemical constituents of GRAS herbs and other economic plants. Boca Raton, Florida.: CRC Press.
  4. 1 2 Lands WE (May 1992). "Biochemistry and physiology of n-3 fatty acids". FASEB Journal. 6 (8): 2530–6. doi:10.1096/fasebj.6.8.1592205. PMID   1592205. S2CID   24182617.
  5. 1 2 Morgan NG, Dhayal S (April 2010). "Unsaturated fatty acids as cytoprotective agents in the pancreatic beta-cell". Prostaglandins, Leukotrienes, and Essential Fatty Acids. 82 (4–6): 231–6. doi:10.1016/j.plefa.2010.02.018. PMID   20206490.
  6. ↑ Acosta-Montaño P, García-González V (March 2018). "Effects of Dietary Fatty Acids in Pancreatic Beta Cell Metabolism, Implications in Homeostasis". Nutrients. 10 (4): 393. doi: 10.3390/nu10040393 . PMC   5946178 . PMID   29565831.
  7. 1 2 Elgersma A, Ellen G, Tamminga S (2004). Rapid decline of contents of beneficial omega-7 fatty acids in milk from grazing cows with decreasing herbage allowance. vdf Hochschulverlag. ISBN   9781351442121. OCLC   1019033379.
  8. ↑ USPatent 9200236B2,Shinde, Sandip&Kale,"Omega 7 rich compositions and methods of isolating omega 7 fatty acids",published 2015-12-01, assigned to Heliae Dev LLC.
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