EICOSAPENTAENOIC ACID: WHAT IS IT, CHEMICAL STRUCTURE, FUNCTIONS - BIOLOGY - 2024

The eicosapentaenoic acid is a polyunsaturated fatty acid omega-3 comprises 20 carbon atoms. It is especially abundant in blue fish such as cod and sardines.

Its chemical structure consists of a long hydrocarbon chain provided with 5 unsaturations or double bonds. It has important biological repercussions, such as the modification of the fluidity and permeability of cell membranes.

Chemical structure of eicosapentaenoic acid. By Edgar181, from Wikimedia Commons.

In addition to these structural repercussions, it has been shown to reduce inflammation, high blood lipid levels, and oxidative stress. Therefore, active compounds based on the chemical structure of this fatty acid are actively synthesized by the pharmaceutical industry, to be used as adjuvants in the treatment of these diseases.

characteristics

Eicosapentaenoic acid is a polyunsaturated ω-3 fatty acid. It is commonly found in the literature as EPA for “Eicosapentanoic Acid”.

It has been widely studied both for its inhibitory effect on inflammatory processes, as well as on triglyceride synthesis in patients with high blood lipid levels.

This fatty acid can be found only in animal cells, being especially abundant in blue sins like sardines and cod.

However, in most of these cells it is synthesized from precursor metabolites, generally other fatty acids of the ω-3 series that are incorporated from the diet.

Chemical structure

EPA is a 20-carbon fatty acid that has five unsaturations or double bonds. Since the first double bond is located three carbons from the terminal methyl, it belongs to the series of polyunsaturated fatty acids ω-3.

This structural configuration has important biological implications. For example, when replacing other fatty acids of the same series or of the ω-6 series in the membrane phospholipids, physical changes are introduced in these that alter the fluidity and permeability of the membrane.

Furthermore, its degradation by β-oxidation in many cases generates metabolic intermediates that act as disease inhibitors. For example, they can act as anti-inflammatories.

In fact, the pharmaceutical industry purifies or synthesizes EPA-based compounds as adjuvants for the treatment of many diseases associated with inflammation and increased blood lipid levels.

Features

Purified eicosapentaenoic acid is used in the treatment of inflammatory diseases. Source: Pixabay.com.

Numerous biochemical studies have identified numerous functions for this fatty acid.

It is known to have an inflammatory effect, since it is capable of inhibiting the transcription factor NF-κβ. The latter activates the transcription of genes that code for pro-inflammatory proteins such as tumor necrosis factor TNF-α.

It also acts as a hypolemic agent. In other words, it has the ability to rapidly decrease blood lipid concentrations when they reach very high values.

It does the latter thanks to the fact that it inhibits the esterification of fatty acids and also reduces the synthesis of triglycerides by liver cells, since it is not a fatty acid used by these enzymes.

Additionally, it decreases atherogenesis or accumulation of lipid substances in the walls of the arteries, which prevents the generation of thrombi and improves circulatory activity. These effects also attribute to EPA the ability to lower blood pressure.

Role of EPA in ulcerative colitis

Ulcerative colitis is a disease that causes excessive inflammation of the colon and rectum (colitis), which can lead to colon cancer.

Currently the use of anti-inflammatory compounds to prevent the development of this disease has been the focus of study of numerous investigations in the area of ​​cancer.

Results from many of these investigations find that the highly purified free eicosapentaenoic acid is capable of acting as a preventive adjuvant of the progress towards this type of cancer in mice.

When giving mice with ulcerative colitis this acid in the diet in concentrations of 1% for a long time, a high percentage of them do not progress to cancer. While those who are not supplied progress to cancer in a higher percentage.

Acids

Fatty acids are molecules of an amphipathic nature, that is, they have a hydrophilic end (soluble in water) and a hydrophobic end (insoluble in water). Its general structure consists of a linear hydrocarbon chain of variable length that has a polar carboxyl group at one of its ends.

Within the hydrocarbon chain, the internal carbon atoms are linked to each other through double or single covalent bonds. Whereas, the last carbon in the chain forms a terminal methyl group that is formed by the union of three hydrogen atoms.

For its part, the carboxyl group (-COOH) constitutes a reactive group that allows the fatty acid to combine with other molecules to form more complex macromolecules. For example, the phospholipids and glycolipids that are part of cell membranes.

Fatty acids have been extensively studied, as they fulfill important structural and metabolic functions in living cells. In addition to being a constituent part of its membranes, its degradation represents a high energy contribution.

As constituents of the phospholipids that make up the membranes, they greatly influence their physiological and functional regulation, since they determine their fluidity and permeability. These latter properties are influential on cellular functionality.

Classification of acids

Fatty acids are classified according to the length of the hydrocarbon chain and the presence or absence of double bonds in:

- Saturated: they lack the formation of double bonds between the carbon atoms that make up their hydrocarbon chain.

- Monounsaturated: those that only have a single double bond between two carbons of the hydrocarbon chain.

- Polyunsaturated: those with two or more double bonds between the carbons of the aliphatic chain.

Polyunsaturated fatty acids can in turn be classified according to the position of the carbon with the first double bond in relation to the terminal methyl group. In this classification, the term 'omega' precedes the number of the carbon that has the double bond.

So, if the first double bond is located between carbons 3 and 4, we will be in a polyunsaturated fatty acid Omega-3 (ω-3), while, if this carbon corresponds to position 6, then we will be in the presence of an acid fatty Omega-6 (ω-6).

References

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3. Kawamoto J, Kurihara T, Yamamoto K, Nagayasu M, Tani Y, Mihara H, Hosokawa M, Baba T, Sato SB, Esaki N. Eicosapentaenoic Acid Plays a Beneficial Role in Membrane Organization and Cell Division of a Cold-Adapted Bacterium, Shewanella livingstonensis Ac10. Journal of bactetiology. 2009; 191 (2): 632-640.
4. Mason RP, Jacob RF. Eicosapentaenoic acid inhibits the formation of the crystalline domain of cholesterol in the membrane induced by glucose through a potent antioxidant mechanism.Biochim Biophys Acta. 2015; 1848: 502-509.
5. Wang Y, Lin Q, Zheng P, Li L, Bao Z, Huang F. Effects of Eicosapentaenoic Acid and Docosahexaenoic Acid on Chylomicron and VLDL Synthesis and Secretion in Caco-2 Cells. BioMed Research International. 2014; Article ID 684325, 10 pages.
6. Weintraub HS. Mechanisms underlying the cardioprotective effects of omega-3 polyunsaturated fatty acids.Postgrado Med. 2014; 126: 7-18.