szterol

Sterols are a class of organic compounds that are part of the lipid family. They are characterized by a specific four-ring structure known as the sterol nucleus, which consists of three six-membered rings and one five-membered ring. This core structure is a defining feature of all sterols, differentiating them from other types of lipids.

The most well-known sterol in animal organisms is cholesterol. Cholesterol plays a crucial role in cell membranes, influencing their fluidity and integrity. It is also a precursor for the synthesis of various vital substances, including steroid hormones like estrogen, testosterone, and cortisol, as well as bile acids, which aid in digestion, and vitamin D, which is important for calcium absorption and bone health.

In plants, phytosterols are the predominant sterols. While structurally similar to cholesterol, phytosterols have different side chains. They are known to have beneficial effects on human health, particularly in reducing cholesterol absorption in the digestive tract. This property has led to their incorporation into functional foods, such as margarines and spreads, marketed for their cholesterol-lowering potential.

Fungi also produce their own unique sterols, the most common being ergosterol. Ergosterol is a vital component of fungal cell membranes and is also the precursor to vitamin D2 when exposed to ultraviolet radiation. The presence of ergosterol in fungal cell membranes makes it a target for antifungal medications, which disrupt fungal cell growth by interfering with its synthesis or function. The diverse roles and widespread occurrence of sterols underscore their fundamental importance in biological systems.