Lipids Not Saponifiable and Steroid Hormones

Lipids Not Saponifiable

• Lipids not saponifiable include: Steroids, prostaglandins, leucotrienes, thromboxanes, carotenoids, and lipid vitamins.
• Steroids are not related to triglycerides, phospholipids, or sphingolipids; they share a basic structure of 17 carbon atoms.
• Important steroids include: sterols, bile acids, female and male sex hormones, corticosteroid hormones, and vitamin D.
• Cholesterol is a well-known sterol. It is a crystalline substance insoluble in water.
• LDL ("bad cholesterol") is a low-density lipoprotein that transports cholesterol to cells.

Steroid Hormones

• Adrenal cortex hormones stimulate glycogen synthesis and fat breakdown, and affect protein metabolism
• Cortisol is a stress hormone
• Androgens (e.g., testosterone) and estrogens/progesterone affect sexual development and function.

Eicosanoids

• Prostaglandins, leukotrienes, and thromboxanes are eicosanoids derived from 20-carbon fatty acids (primarily arachidonic acid).
• Prostaglandins are crucial in various physiological processes, including regulating blood pressure, blood clotting, and inflammation.
• Prostaglandins were first isolated from the prostate, and are found in all tissues.
• They play crucial roles in medicine and pharmacology.
• Prostaglandins influence blood pressure and blood circulation.

Leukotrienes

• Leukotrienes are involved in various inflammatory responses and allergic reactions.

Thromboxanes (TX)

• Thromboxanes are powerful metabolites of prostaglandins that stimulate platelet aggregation and vasoconstriction.

Carotenoids

• Carotenoids are pigments that give color to foods.
• They are insoluble in water and are a source of vitamin A.

Vitamins (Lipophilic)

• Vitamins A, D, E, and K are fat-soluble vitamins.
• Vitamin A is vital for vision and growth, derived from carotenoids.
• Vitamin D regulates calcium and phosphorus absorption, critical for bone formation.
• Vitamin E acts as an antioxidant by preventing premature cell damage.
• Vitamin K is crucial for blood clotting.