Question

Lipoxygenase pathway leads to formation of

• A. Prostaglandins
• B. Prostanoids
• C. Leukotrienes
• D. Unsaturated fatty acids

Hint:

- COX pathway $\rightarrow$ Prostaglandins, Prostacyclins, Thromboxanes
- LOX pathway $\rightarrow$ Leukotrienes, Lipoxins
These pathways represent different targets for anti-inflammatory therapies.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Arachidonic acid is a 20-carbon polyunsaturated fatty acid incorporated into cell membrane phospholipids.
Upon cell activation, arachidonic acid is released by the enzyme phospholipase $\text{A}_2$.
It then serves as the substrate for two primary metabolic pathways: the cyclooxygenase (COX) pathway and the lipoxygenase (LOX) pathway.

Step 2: Detailed Explanation:
The metabolic pathways of arachidonic acid generate distinct classes of biologically active lipid mediators known as eicosanoids:
The Cyclooxygenase (COX) pathway: The enzymes COX-1 and COX-2 convert arachidonic acid into prostaglandin $\text{H}_2$, which is subsequently converted by specific synthases into prostaglandins, prostacyclins, and thromboxanes (collectively termed prostanoids).
The Lipoxygenase (LOX) pathway: The enzyme 5-lipoxygenase (5-LOX), along with its helper protein 5-lipoxygenase-activating protein (FLAP), catalyzes the oxidation of arachidonic acid to produce 5-hydroperoxyeicosatetraenoic acid (5-HPETE).
This intermediate is then metabolized to form leukotriene $\text{A}_4$ ($\text{LTA}_4$).
$\text{LTA}_4$ is subsequently converted into other leukotrienes, such as $\text{LTB}_4$, $\text{LTC}_4$, $\text{LTD}_4$, and $\text{LTE}_4$.
Leukotrienes are potent chemical mediators that play roles in inflammatory and allergic responses, causing bronchoconstriction and microvascular leakage.

Step 3: Final Answer:
The lipoxygenase pathway is responsible for the formation of leukotrienes.