Question

Which of the following are polyunsaturated fatty acids (n-6)?
(A). Linoleic
(B). \(\gamma\)- Linolenic
(C). Arachidonic
(D). Oleic
Choose the most appropriate answer from the options given below:

• A. (A), (B) and (D) only.
• B. (A), (B) and (C) only.
• C. (A), (B), (C) and (D).
• D. (B), (C) and (D) only.

Hint:

Remember the three key fatty acid families:
\textbf{n-6 Family Head:} Linoleic Acid (LA)
\textbf{n-3 Family Head:} \(\alpha\)-Linolenic Acid (ALA)
\textbf{n-9 Family Head:} Oleic Acid (OA)
Arachidonic acid and \(\gamma\)-linolenic acid are derived from linoleic acid, so they are also in the n-6 family.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Fatty acids are classified based on the number of double bonds (saturation) and the position of the first double bond from the methyl end (omega or n- position). A polyunsaturated fatty acid (PUFA) has two or more double bonds. An n-6 (or omega-6) fatty acid has its first double bond at the sixth carbon atom from the methyl end.
Step 3: Detailed Explanation:
Let's analyze each fatty acid:
- (A) Linoleic acid (LA): Its notation is 18:2(n-6). It has 18 carbons and 2 double bonds, with the first at the 6th carbon. It is an n-6 PUFA.
- (B) \(\gamma\)-Linolenic acid (GLA): Its notation is 18:3(n-6). It has 18 carbons and 3 double bonds, with the first at the 6th carbon. It is an n-6 PUFA. (This is different from \(\alpha\)-linolenic acid (ALA), which is an n-3 PUFA).
- (C) Arachidonic acid (AA): Its notation is 20:4(n-6). It has 20 carbons and 4 double bonds, with the first at the 6th carbon. It is an n-6 PUFA.
- (D) Oleic acid (OA): Its notation is 18:1(n-9). It has only one double bond, so it is a monounsaturated fatty acid (MUFA), not a PUFA. Also, its double bond is at the n-9 position.
Therefore, Linoleic, \(\gamma\)-Linolenic, and Arachidonic acids are all n-6 PUFAs.
Step 4: Final Answer:
The fatty acids that fit the description of n-6 polyunsaturated are (A), (B), and (C). This corresponds to option (B).