Sterols

Sterols are a class of lipid compounds that contain several ring structures, which vary according to their extra-ring groups. Sterols are a class of lipid compounds that contain several ring structures, which vary according to their extra-ring groups. Sterols are essential for almost all eukaryotes and are lipids with many different biological functions. In plants they are mainly phytosterols, whereas in animals they are mainly cholesterol. Sterols in fungi and plants are mainly lipids with carbon atoms 28-29, whereas cholesterol in animals is mainly a lipid with carbon atom 27. BOC Sciences provides various high-purity sterols and their derivatives to contribute to research and applications such as drug discovery, nutrition, and cosmetics. In addition, we offer a range of custom liposome services for you to choose from. At BOC Sciences, you're sure to make a difference in liposomes.

What are Sterols?

Sterols are a class of steroids, which are steroids containing hydroxyl groups. They are all cyclopentane polyhydrophenanthrene as the basic structure and contain hydroxyl groups, so they are called sterols. They are widely found in the cells and tissues of plants and animals, except for their absence in bacteria. Sterols have a variety of biological functions, such as being components of cell membranes and constituting adrenocorticotropic hormones and sex hormones. Many plant sterols also have strong pharmacological or toxicological effects, such as digitalis and wowbane can enhance the contraction of the heart muscle, is the treatment of heart failure. Plants contain β-glutosterol and yeast contains ergosterol. Steroids in animals are most abundant in cholesterol, which can be converted into steroid hormones in the body - progesterone, estradiol, testosterone, cortisol and aldosterone. Many contraceptives are derivatives of progesterone.

Sterols Structure

The defining feature of sterols is their steroid ring structure, which consists of four fused rings—three six-membered rings and one five-membered ring - forming a rigid, hydrophobic core. Attached to this core is a hydroxyl group (-OH) at the 3-position, which is polar and capable of forming hydrogen bonds with other molecules. This structure allows sterols to interact with the lipid bilayer of cell membranes, where they function as both structural and signaling molecules. The variation in sterol molecules comes from the functional groups attached to the rings or the side chain, which can significantly affect their biological activity. For instance, the presence of a double bond in the B-ring (as in the case of campesterol) or a methyl group at the C-24 position (as in stigmasterol) can alter how these sterols interact with membrane lipids, receptors, and enzymes.

The structure of sterols.

What are Plant Sterols?

Plant sterols, or phytosterols, are the plant-based equivalents of cholesterol. They are structurally similar but differ in the side chains attached to the steroid nucleus. Phytosterols are synthesized by plants to serve a similar role in maintaining cell membrane integrity as cholesterol does in animals. These compounds are predominantly found in vegetable oils, nuts, seeds, legumes, and whole grains. The biological importance of plant sterols extends beyond their structural role in plants. In humans, they are known to reduce LDL cholesterol levels, a beneficial effect that has been widely documented. This has made phytosterols a key ingredient in cholesterol-lowering functional foods such as margarine, milk, and juices.

Examples of Sterols

Cholesterol: The Key Animal Sterol

Cholesterol is the most prevalent sterol in animal cells, and its importance cannot be overstated. It is a fundamental component of cell membranes, where it helps to maintain membrane fluidity and integrity. Cholesterol modulates the membrane's physical properties, ensuring that it remains flexible yet stable under varying conditions of temperature and pressure. Additionally, cholesterol plays a pivotal role in the formation of lipid rafts, microdomains in the membrane that concentrate signaling molecules and proteins involved in cellular communication.

Cholesterol also serves as a precursor in the synthesis of steroid hormones, including glucocorticoids, mineralocorticoids, and sex hormones such as estrogen, testosterone, and progesterone. Beyond hormones, cholesterol is essential for the production of bile acids, which aid in the digestion and absorption of fats, and vitamin D, which is synthesized through cholesterol under the influence of ultraviolet light.

Phytosterols: The Key Plant-Based Sterols

Phytosterols are structurally similar to cholesterol but are found predominantly in plants. These compounds are essential for maintaining the structural integrity of plant cell membranes, performing a function analogous to cholesterol in animals. The most common phytosterols include β-sitosterol, campesterol, and stigmasterol.

Phytosterols are of considerable interest due to their health benefits, particularly in relation to cardiovascular health. Studies have shown that phytosterols can help lower LDL cholesterol levels by inhibiting cholesterol absorption in the intestines. This has led to their widespread use in functional foods and nutritional supplements aimed at managing cholesterol levels and reducing the risk of heart disease. Additionally, phytosterols have demonstrated anti-inflammatory and antioxidant properties, making them beneficial in preventing chronic diseases such as cancer, neurodegenerative conditions, and arthritis.

Sterol Biosynthetic Process

Sterol biosynthesis involves a complex series of enzymatic reactions starting from acetyl-CoA. The pathway progresses through the formation of mevalonate and isoprenoid intermediates, eventually leading to the production of the sterol backbone.

• In plants, the synthesis of sterols is a highly regulated process that is influenced by environmental conditions, such as light and temperature. The process of sterol biosynthesis is also essential for the production of plant hormones, including brassinosteroids, which are involved in growth and development.
• In animals, sterol synthesis begins with the conversion of acetyl-CoA to mevalonate through the action of the enzyme HMG-CoA reductase, the target of statins, the most widely prescribed cholesterol-lowering drugs. The process culminates in the synthesis of cholesterol, which can be further modified into various bioactive molecules such as bile acids, vitamin D, and steroid hormones.

Sterols Function

Sterols are pivotal molecules in both plants and animals, performing a wide array of functions that are crucial for maintaining cellular integrity and supporting various physiological processes.

Structural Component of Cell Membranes

Sterols, including cholesterol in animals and phytosterols in plants, are essential for maintaining cell membrane fluidity, stability, and permeability. Cholesterol prevents membranes from becoming too rigid or too fluid, while phytosterols ensure membrane integrity in plants under environmental stress.

Precursor for Bioactive Molecules

Cholesterol is a precursor for steroid hormones (e.g., cortisol, estrogen), bile acids for fat digestion, and vitamin D, which supports calcium balance and immune function. These molecules regulate vital processes like metabolism, immune response, and reproduction.

Regulation of Membrane Proteins and Lipid Rafts

Sterols contribute to lipid raft formation, which concentrates signaling molecules and receptors. Cholesterol stabilizes membrane proteins, ensuring proper function in processes like signal transduction, endocytosis, and cell communication.

Cell Signaling and Gene Expression

Sterols influence cell signaling by interacting with receptors like GPCRs and can act as signaling molecules themselves. Oxysterols regulate gene expression, particularly for cholesterol homeostasis, by binding to nuclear receptors like LXRs.

Antioxidant and Anti-inflammatory Properties

Phytosterols, such as β-sitosterol, have antioxidant and anti-inflammatory effects. They neutralize free radicals, reduce inflammation, and may help protect against diseases linked to chronic inflammation, like cardiovascular disease and arthritis.

Sterols vs Stanols

Sterols and stanols are related compounds with distinct biological activities, especially in cholesterol metabolism and health. Sterols, such as cholesterol and phytosterols, have a double bond at the 5-position in their steroid ring, contributing to flexibility in cell membranes. Stanols, or saturated sterols, have a hydrogenated form with a saturated bond at the same position, making them more rigid.

Cholesterol-Lowering Effects

Both lower LDL cholesterol but through different mechanisms:

• Sterols: Compete with dietary cholesterol for absorption in the intestines, reducing cholesterol uptake.
• Stanols: More effective at lowering LDL by blocking cholesterol absorption and promoting its excretion, potentially reducing LDL by 15-20%.

Mechanisms of Action

• Sterols: Reduce cholesterol absorption by competing for transport pathways in the intestine, but are less effective than stanols.
• Stanols: Their rigid structure leads to more efficient blockage of cholesterol absorption and enhanced cholesterol excretion.

Health Benefits Beyond Cholesterol-Lowering

• Sterols: Have anti-inflammatory and antioxidant properties, potentially supporting cardiovascular health.
• Stanols: In addition to lowering LDL cholesterol, they may improve arterial function and reduce blood pressure, offering stronger cardiovascular protection.

Why Choose BOC Sciences' Sterols?

• High Purity: BOC Sciences' proprietary and efficient separation and purification technologies ensure the high purity and quality of sterols products.
• Comprehensive Range: BOC Sciences' sterol products cover a comprehensive range of classes, enabling a wide range of applications. And, our sterols customization services are available to meet your additional needs.
• Rapid Delivery: Products on the BOC Sciences website are replenished in a timely manner, with stock available for fast delivery.
• Professional Support: BOC Sciences' dedicated team can provide a full range of technical advice and support services to ensure that customers can use sterols to run their projects smoothly.

Sterols are essential molecules with diverse biological functions, ranging from maintaining cell membrane integrity to serving as precursors for hormones and vitamins. The benefits of sterols, especially plant-based phytosterols, extend to health applications, such as lowering cholesterol and reducing inflammation. BOC Sciences offers high-quality sterol products and technical support to meet the growing demands in pharmaceuticals, biotechnology, and nutrition. Whether you are looking for custom sterol solutions or require technical guidance, BOC Sciences provides reliable, efficient, and scientifically-backed services to ensure your projects succeed.