The Role of Antioxidants in Vascular Protection
Free radicals and lipid peroxidation (LPO) are major triggers of the atherosclerotic process. Antioxidants suppress these reactions by reducing radicals to stable forms.
Based on their mechanism of action, they are classified into:
- Direct: independently bind and inactivate free radicals.
- Indirect: stimulate the body's own protective antioxidant systems.
Natural protectants include ascorbic acid (vitamin C), vitamins A and D, tocopherols (vitamin E), and carotenoids. Statins also exhibit important pleiotropic (additional) antioxidant effects.
Key Antioxidant Medications
Several specific agents are used in the combination therapy of atherosclerosis:
- Probucol. A lipophilic bisphenol structurally similar to vitamin E. It works in two directions: inhibits LPO (prevents foam cell formation in the intima) and lowers LDL levels by activating their hepatic uptake. Major drawback: it concurrently decreases levels of antiatherogenic HDL. The drug is poorly absorbed (2–6%), deposits in adipose tissue, and its peak effect is reached only after 1–3 months of regular intake.
- Eiconol. A marine-derived complex containing 20% omega-3 triglycerides (eicosapentaenoic and docosahexaenoic acids), as well as vitamins A, D, and E. It normalizes lipoprotein structure, dilates blood vessels, lowers blood pressure, and combats arrhythmias.
- Pumpkin seed oil preparation (Cucurbita pepo). A plant-based agent containing phospholipids, vitamins B, C, PP, tocopherols, and flavonoids. Aside from normalizing the lipid profile, it acts as a hepatoprotectant, choleretic, and anti-inflammatory agent, and is used in urology to inhibit prostate cell proliferation.
Mechanism of Antiplatelet Action of Omega-3
The efficacy of polyunsaturated fatty acids (PUFAs) is related to their interference with arachidonic acid metabolism.
- Eicosapentaenoic acid competes with arachidonic acid in eicosanoid synthesis pathways.
- As a result, prostanoids are formed with three double bonds instead of two.
- Thromboxane $A_3$ is synthesized, which induces platelet aggregation significantly less than the arachidonic acid derivative, thromboxane $A_2$.
- Against this background, the activity of prostacyclins (natural antiplatelet agents) increases.
Conclusion: the biochemical balance shifts toward substances that prevent thrombus formation.
Angioprotectors: Targets and Clinical Use
Angioprotectors act directly on the blood vessel wall: they normalize metabolism within it, decrease permeability, and improve microcirculation. They are prescribed for vascular lesions of any caliber:
- Arteries. In atherosclerosis, plaques form in the tunica intima. Angioprotectors reduce vascular wall permeability, preventing atherogenic lipoproteins from penetrating inward. They are strictly used alongside lipid-lowering and antithrombotic medications.
- Veins. In varicose veins and thrombophlebitis, these drugs relieve edema and decrease wall permeability. They are used in combination with venotonics, NSAIDs, and anticoagulants.
- Capillaries. They protect small vessels during acute infections (e.g., capillarotoxicosis in influenza) and guard against chronic diabetic angiopathies (specifically, retinal vascular lesions in insulin-dependent diabetes).