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.
- Chemistry of Essential Fatty Acids
- Chemical Properties of Essential Fatty Acids
- Sources of Essential Fatty Acids
- Synthesis of Essential Fatty Acids
- Functions of Essential Fatty Acids
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.