What is the Difference Between Arachidic Acid and Arachidonic Acid

The main difference between arachidic acid and arachidonic acid is that arachidic acid is a saturated fatty acid, while arachidonic acid is a polyunsaturated fatty acid.

Fatty acids are the building blocks of fat that are present in the body and the food we eat. Fat is broken down into fatty acids in the process of digestion and then absorbed into the body. Fatty acids are usually joined together in threes to make triglycerides. Moreover, they consist of an even number of carbon atoms, with hydrogen atoms along the length of the chain, and one end of the chain has a carboxyl group. Arachidic acid and arachidonic acids are two types of fatty acids.

Key Areas Covered

1. What is Arachidic Acid 
     – Definition, Features
2. What is Arachidonic Acid
     – Definition, Features
3. Difference Between Arachidic Acid and Arachidonic Acid
     – Comparison of Key Differences

Key Terms

Arachidonate, Arachidic Acid, Arachidonic Acid, Eicosanoic acid, n-Eicosanoic acid, Icasonoic acid, Immunocytophyte

What is Arachidic Acid

Arachidic acid is a type of saturated fatty acid. It has a molecular formula of C₂₀H₄₀O₂. Its molecular weight is 312.538 g·mol⁻¹. It is also known as Icasonoic acid, Eicosanoic acid, or n-Eicosanoic acid. This compound belongs to a class of long-chain fatty acids. These are fatty acids with an aliphatic tail that contains between 13 to 21 carbon atoms. They are neutral compounds and are very hydrophobic.

Arachidic acid has a chain of 20 carbons. Its melting point is 75.4°C while its boiling point is 328°C. The density is 0.8240 g/cm³. It is a white and crystalline compound that is insoluble in water. Moreover, it is available naturally as a minor component in peanut oil. It is also present in some vegetables, fats, and oils; in these sources, it occurs as a glycerol ester. It is also present in butter, corn oil, cocoa butter, and perilla oil.

The esters and salts of arachidic acid are known as arachidates. They can form by the hydrogenation of arachidonic acid. Arachidyl alcohol is produced by the reduction of arachidic acid. Generally, lubricants, photographic materials, and detergents use arachidic acid as a constituent.

What is Arachidonic Acid

Arachidonic acid is a long-chain fatty acid that has 20 carbon atoms. Its molecular formula is C₂₀H₃₂O₂. Arachidonic acid may also be called Arachidonate or Immunocytophyte.  Arachidonic acid has a molecular weight of 304.5 g mol-1. It is an unsaturated essential fatty acid. Arachidonic acid is present in human and animal fat, liver, glandular organs, brain, and in animal phosphatides.

It has a boiling point of 169°C, a melting point of -49°C, and a density of 922 kg/m³. Its molar mass is 304.47 g/mol. Its IUPAC ID is (5Z,8Z,11Z,14Z)-Icosa-5,8,11,14-tetraenoic acid. It is soluble in ethanol. Moreover, it’s a polyunsaturated fatty acid with four double bonds. Generally, the addition of two additional carbon atoms to linoleic acid and further desaturation forms arachidonic acid.

Moreover, arachidonic acid is pro-inflammatory and immuno-supportive. In fact, it is one of the most important omega-6 fatty acids. Omega 6 fatty acids are present in legumes, grains, nuts, and seeds. It is also available mostly in the fatty parts of fish and meat. Hence, vegetarians have lower levels of arachidonic acid than people who consume fish and meat.

Furthermore, arachidonic acid is essential to the operation of the prostaglandin system, prostaglandins being a part of a class of eicosanoids. These classes of chemical compounds play a critical role in inflammations, hemorrhages, vasoconstriction, vasodilation, blood pressure, as well as immune function.

Difference Between Arachidic Acid and Arachidonic Acid

Definition

Arachidic acid is a saturated fatty acid, while arachidonic acid is a polyunsaturated fatty acid.

Type of Fatty Acid

While arachidic acid is a nonessential fatty acid, arachidonic acid is an essential fatty acid.

Molecular Formula

The molecular formula of arachidic acid is C₂₀H₄₀O₂, whereas the molecular formula of arachidonic acid is C₂₀H₃₂O₂.

Molar Mass

The molar mass of arachidic acid is 312.538 g·mol^-1 but the molar mass of arachidonic acid is 304.5 g mol^-1.

Uses

Arachidic acid is mainly useful in industrial applications (in the production of detergents, lubricants, coatings, etc.), while arachidonic acid is an important nutrient with significant biological functions in the body.

Conclusion

Arachidic acid and arachidonic acids are two different types of fatty acids. The main difference between arachidic acid and arachidonic acid is that arachidic acid is a saturated fatty acid, while arachidonic acid is a polyunsaturated fatty acid.

Reference:

1. “Arachidic acid.” National Library of Medicine. 
2. “Arachidonic acid.” National Library of Medicine. 

Image Courtesy:

1. “Arachidic formula representation” By LadyofHats – Own work (CC0) via Commons Wikimedia