Abstract
As a nutritional and healthy raw material, phospholipids have attracted more and more attention. Research has found that phospholipids are directly or indirectly related to many activities of living organisms. This article briefly introduces phospholipids from several aspects such as their classification, physical and chemical properties, and physiological effects.
1. Classification of phospholipids
Phospholipids are various phosphorus-containing lipids. They are widely distributed in nature and come in many varieties. According to their chemical composition, they can be roughly divided into two categories. One type contains glycerol in the molecule and is called glycerophospholipid; the other type contains neuroamino acids in the molecule and is called sphingomyelin. Glycerophospholipids are further divided into neutral glycerophospholipids and acidic glycerophospholipids according to their different properties. The former includes phosphatidylcholine (lecithin, PC), phosphatidylethanolamine (cephalin, plasmalogen), lysophosphatidylcholine and soybean phospholipids; the latter includes phosphatidic acid (phosphatidic acid), phosphatidylserine, Diphosphatidylglycerol (cardiolipin), etc. Neuraminols in sphingolipids are a series of unsaturated amino alcohols (alkamines) with different carbon chain lengths, the most common of which contains 18 carbon atoms. They often exist in phospholipids in the form of amides or brain amide, such as brain amide phosphocholine (sphingomyelin, sphingomyelin), brain amine glycerol phosphate, etc.
2. Properties of phospholipids
Phospholipids are soluble in water because they contain glycerol and phosphoric acid. It also contains fatty acids, so it is soluble in fatty solvents. But phospholipids, unlike other lipids, do not dissolve in acetone. Based on this characteristic, phospholipids can be separated from other lipids. The solubilities of phosphatidylcholine, cephalin and sphingomyelin are significantly different in different fat solvents, and can be used to separate these three phospholipids.
Sphingomyelin is very stable and insoluble in ether and cold ethanol, but soluble in benzene, chloroform and hot ethanol. Phosphatidylcholine is a white waxy substance that is easily oxidized in the air and quickly turns into dark brown, possibly due to the oxidation of USFA in the phospholipid molecules. Sphingomyelin is relatively stable to oxygen, unlike phosphatidylcholine and cephalin. Phosphatidylcholine has the ability to reduce surface tension. If combined with proteins or sugars, it will have a greater effect. It is an extremely effective fat emulsifier. It combines with other lipids and diffuses evenly throughout the body’s water system. Therefore, water-insoluble lipids can be kept in an emulsified state. Both phosphatidylcholine and cephalin can be hydrolyzed by enzymes. The venom of cobras and rattlesnakes contains phosphatidylcholinease, which hydrolyzes phosphatidylcholine and loses a molecule of fatty acid to become lysophosphatidylcholine, which has a strong hemolytic effect. This enzyme also has a similar effect on cephalin, but its product has poor hemolytic ability.
3. Physiological effects of phospholipids
Phospholipids are important components of biological membranes
Phospholipids can combine with proteins to form lipoproteins, and in this form constitute various membranes of cells, such as cell membranes, nuclear membranes, mitochondrial membranes, etc., maintaining the normal shape and function of cells and organelles. Lecithin is found in cell membranes, and cardiolipin is found in mitochondrial membranes. Due to the double bonds in the USFA molecules in phospholipids, biological membranes have good fluidity and special permeability. These membranes play an important role in metabolism in the body. Enzymes can be regularly arranged on the membrane, allowing substance metabolism to proceed regularly and smoothly, ensuring the normal physiological functions of cells.
Phospholipids can promote growth
After humans or animals take phospholipids, it can be seen that the mitochondria in white blood cells increase and enlarge than before taking it, thereby accelerating the formation of hemoglobin and promoting the production of red blood cells in the bone marrow and hematopoietic organs.
Nervous tissue contains a large amount of phospholipids
As far as the central nervous system is concerned, 51%-54% of its dry weight is lipids, and more than half of them are phospholipids, and phospholipids are related to nerve excitation. In recent years, phosphatidylcholine (lecithin) has been used as a health food in China because of its special effects. Phosphatidylcholine can be broken down into choline in the digestive tract. It is a neurotransmitter that conducts information in the brain and promotes thinking and memory abilities.
The effect of lecithin on hormones
Phosphatidylinositol monophosphate is closely related to norepinephrine receptors. Experiments have shown that the two have strong binding force, and bivalent metal ions such as Ca2+ and Mg2+ can affect their binding. Therefore, it is believed that phosphatidylinositol monophosphate may be a component of norepinephrine receptors.
The activities of many enzymes on the membrane are closely related to phospholipids
Removal of phospholipids with acetone or destruction of phospholipids with specific phospholipases can cause the activity of such enzymes to decrease or be completely lost. In addition, the prosthetic group of thromboplastin contains cephalin, so cephalin is also related to blood coagulation.
Phospholipids are an important component of plasma lipoproteins
Phospholipids stabilize lipoproteins. When lipids in tissues, such as fat and cholesterol, are transported in the blood, sufficient phospholipids are required to proceed smoothly. In bile, phospholipids form colloids together with bile salts and cholesterol to facilitate the dissolution and excretion of cholesterol.
The content of phosphatidylcholine in the liver is very high, most of which is used to make lipoproteins. If phosphatidylcholine is insufficient, less lipoproteins are synthesized, and the large amount of fat synthesized by the liver cannot be effectively transported. Excessive accumulation of fat in liver cells leads to the formation of fatty liver. Phosphatidylcholine has the ability to prevent fatty liver. Effect. ComingClinical trials have shown that soy phosphatidylcholine has certain effects on cirrhosis and hepatitis.
Phosphatidylcholine is a strong emulsifier
It can effectively emulsify fat and cholesterol in the blood, keep it in a suspended state, prevent it from being deposited on the blood vessels, keep the blood flow smooth, and prevent the sclerosis of the heart and brain blood vessels.
Phosphatidylcholine can also enhance endurance and resist fatigue
Because phospholipids can maintain good tension and elasticity in the alveoli, significantly improve the ventilation and ventilation capabilities of the lungs, and increase the amount of oxygen entering and exiting the lungs per unit time. At the same time, phosphatidylcholine can promote the toughness and elasticity of red blood cell membranes and prevent the destruction of red blood cells after prolonged or strenuous exercise. Red blood cells can carry oxygen and supply the oxygen needs of muscles, brain and other tissues. Therefore, phosphatidylcholine can improve the body’s tolerance to hypoxia, maintain strong muscle vitality, increase endurance, and resist fatigue.
In summary, phospholipids have high nutritional value and physiological functions, and are directly or indirectly related to many activities of living organisms. In recent years, phospholipids have been increasingly used in nutritional and health products. Especially in many developed countries such as the United States and the United Kingdom, phospholipids have received widespread attention. Research has found that in terms of pet nutrition and health, phospholipids have the effect of moisturizing pet skin and beautifying their hair. At the same time, phospholipids are also necessary for the development of young dogs and cats, and have a protective effect on pet heart paint additives and livers, and can also prevent and Assists in the treatment of pet diabetes and gallstones, etc.
