**Core Concept**
Isoprostanes are a class of eicosanoid biomarkers that are formed in vivo from the free radical-catalyzed peroxidation of polyunsaturated fatty acids, particularly arachidonic acid. This process occurs independently of the cyclooxygenase (COX) enzyme and is a marker of oxidative stress.

**Why the Correct Answer is Right**
Isoprostanes are formed through a non-enzymatic mechanism, where free radicals abstract hydrogen atoms from arachidonic acid, leading to the formation of a fatty acid peroxide. This peroxide is then converted into an isoprostane through a series of reactions involving the enzyme 15-hydroxyprostaglandin dehydrogenase (15-PGDH). The resulting isoprostane is a stable end product that can be used as a biomarker of oxidative stress in various diseases.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because isoprostanes are not formed through the enzymatic action of COX-1 or COX-2, which are responsible for converting arachidonic acid into prostaglandins and thromboxanes.
* **Option B:** This option is incorrect because lipoxygenases are involved in the formation of leukotrienes from arachidonic acid, not isoprostanes.
* **Option C:** This option is incorrect because cytochrome P450 enzymes are involved in the metabolism of various substrates, but not in the formation of isoprostanes from arachidonic acid.

**Clinical Pearl / High-Yield Fact**
Isoprostanes have been implicated as potential biomarkers of oxidative stress in various diseases, including atherosclerosis, diabetes, and neurodegenerative disorders. They have also been shown to have vasoactive properties and may play a role in the pathogenesis of these diseases.

**Correct Answer:** D