Essential Fatty Acids: Chemistry, Synthesis and Functions

In this article we will discuss about the Essential Fatty Acids:- 1. Chemistry of Essential Fatty Acids 2. Chemical Properties of Essential Fatty Acids 3. Sources 4. Synthesis 5. Functions.

Contents:

1. Chemistry of Essential Fatty Acids
2. Chemical Properties of Essential Fatty Acids
3. Sources of Essential Fatty Acids
4. Synthesis of Essential Fatty Acids
5. Functions of Essential Fatty Acids

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1. Chemistry of Essential Fatty Acids:

Linoleic acid and linolenic acid contain 18 carbon atoms each and aracjhidonic acid contains 20 car­bon atoms. Linoleic acid, linolenic acid and arachi­donic acid have 2, 3 and 4 double bonds, respec­tively, in their structure.

Their structures are:

2. Chemical Properties of Essential Fatty Acids:

a. The essential fatty acids of vegetable oils have low melting point and low iodine number.

b. These essential fatty acids become satu­rated on hydrogenation and the oils are converted to solid fats.

3. Sources of Essential Fatty Acids:

a. Linoleic acid occurs in high concentra­tions in various edible vegetable oils e.g., corn, cotton seed, peanut, safflower.

b. Arachidonic acid occurs in animal fats, al­though in small amounts.

4. Synthesis of Essential Fatty Acids:

Lenoleic acid cannot be synthesized by animals and, therefore, must be supplied preformed in the diet. Arachidonic acid can be formed from linoleic acid in the animal body.

The pathway is first by dehydrogenation of the CoA ester through γ-linolenate followed by the addition of a 2 carbon unit (as acetyl-CoA in the mitochondrial system for chain elongation or as malonyl-CoA in the microsomal system, which is the more active system) to give eicosatrienoate (homo γ-linolenate) which further forms arachidonate by dehydrogenation.

Therefore, the nutritional requirement of arachidonate is compen­sated by the linoleate in the diet. The synthesis is shown in Fig. 18.33.

5. Functions of Essential Fatty Acids:

a. Essential fatty acids found in the struc­tural lipids of the cell are concerned with the structural integrity of the mitochon­drial membrane.

b. These occur in high concentration in the reproductive organs.

c. These effect the prolongation of clotting time and increase the fibrinolytic activ­ity.

d. These are esterified and emulsified with cholesterol and thus retard atherosclero­sis.

e. These are incorporated into lipoproteins for transport to the liver for further oxida­tion.

f. These are present in phospholipids, mainly in the position 2.

g. The fatty livers due to deficiency of the essential fatty acids are cured only by the reintroduction of these substances into the diet.

h. The deficiency of these essential fatty ac­ids causes skin lesion and impairment of lipid transfer.

i. The deficiency of these substances in the diet of babies also causes eczema.