**2.4 Compositional analysis of algal oil**

Algal oil is very high in unsaturated fatty acids [39]. The mentioned fatty acids are present in abundance in algal oil [40].

• Arachidonic acid (AA)

It is an unsaturated, essential long chain (C20) fatty acid and acts as a precursor in the biosynthesis of prostaglandins, thromboxanes, and leukotrienes.

• Eicospentaenoic acid (EPA)

EPA is an omega-3 fatty acid. Omega-3 fatty acid helps lower risk of heart disease, lower triglycerides in the blood, blood pressure, and inflammation.

**Figure 2.**

*Microalgal oil and further trans-esterification to bio-diesel extraction procedure.*

• Docasahexaenoic acid (DHA)

DHA is a long-chain, highly unsaturated omega-3 fatty acid. It affects cell and tissue physiology and function by altering the membrane structure. It also has prominent roles in membrane protein function, cellular signaling and production of lipid mediator.

• Gamma-linolenic acid (GLA)

GLA is an essential fatty acid belonging to omega-6 fatty acid. Omega-6 fatty acids play a crucial role in brain function, growth and development, stimulate skin and hair growth, maintain bone health, regulate metabolism, and maintain the reproductive system.

• Linoleic acid (LA)

It is an essential fatty acid belonging to the omega-3 group. It has been reported to inhibit the synthesis of prostaglandin resulting in reduced inflammation and prevention of certain chronic diseases.
