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Lipid Peroxidation

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Lipids: An Introduction

Although lipids are a subclass of fats called triglycerides, the word "lipid" is sometimes used as a synonym for fats. Organic molecules called lipids are found throughout nature. Additionally, they are insoluble. Lipid synthesis occurs in the liver of the human body. The sources that are high in lipids include whole milk, butter, cheese, and ghee oil.

What are Lipids?

Organic substances known as lipids are insoluble in water. They are recognised as fatty acids that can dissolve in nonpolar solvents like fats, grease oils, and other similar substances. Lipid molecules are hence nonpolar by nature. Important sources of lipids include whole milk, butter, cheese, ghee, and oil. Lipids are essentially molecules consisting of hydrocarbons. The structural and functional building elements of living cells are also known as lipids.

Types of Lipids

According to how complex their structural makeup is, lipids are divided into two categories: Simple Lipids and Complex Lipids. The succinct explanations of each are as follows:

Simple Lipids: Simple lipids can be found in nature either alone or in combination with alcohol. Furthermore, the ester bond is responsible for the mixing of alcohol. These lipids are triacylglycerol (TAG) and wax esters, which include long-chain fatty acids. The non-polar molecules are known as TAGs. They lack free polar molecules, which is why they are non-polar. TAGs are observed as oil droplets in aqueous cytosol under the microscope. The simplest fatty acid esters are waxes, which are also a kind of simple lipids. Actually, the plankton's energy comes from waxes. The waxes have a greater melting point than TAGs.

Complex Lipids: Lipids with three or more chemical constituents are referred to as complex lipids. Glycerol, fatty acids, sugar, one-log chain bases, and other substances are examples of these components. Complex lipids possess polar properties. Complex lipids actually come in a variety of forms. Phospholipids are what they are. Sulpholipids, lipoproteins, and glycolipids. According to definitions of complex lipids, these many forms of complex lipids include lipids combined with additional substances. Phospholipids are a combination of phosphoric acid, nitrogenous base, and lipid. Lipids and carbohydrates are combined to create glycolipids. Sulfur and lipid combine to generate sulpholipids. Protein and fat are combined to generate lipoproteins.

Lipid Peroxidation

When the lipids deteriorate due to oxidation, lipid peroxidation occurs. Additionally, this process is brought on by the interaction of lipids with substances associated with oxygen. Lipid peroxidation is a crucial mechanism that occurs in both plants and mammals.

Initiation, Propagation, and Termination are the three phases of the lipid peroxidation process. The three procedures are explained in the paragraphs that follow:

Initiation: In this phase, a hydrogen atom reacts with reactive oxygen species like hydroxyl radical to produce fatty acid radicals. The most common initiators in this step of lipid peroxidation are substances from the reactive oxygen family. Some examples of the initiators are reactive oxygen species like hydroxides (OH) and hydrogen superoxide (OOH). These species are also utilised as initiators because of their capacity to interact with hydrogen atoms to produce water and radical fatty acids.

Propagation: In this phase, free and unstable fatty acids combine with oxygen in a molecular state to create peroxyl-fatty acid radicals. Lipid hydroperoxides and acid-reactive molecules are also produced during the propagation process. Because they react with other free fatty acids and are extremely unstable, the radicals produced during the propagation stage can produce a variety of fatty radical species. As the freshly generated fatty radical acid continues to react in the same manner, this cycle can last for quite some time.

Termination: Lipid peroxyl radicals combine with other molecules that contain comparable radicals to create non-radical products during the process known as termination. The peroxyl-fatty acid chain reaction comes to a halt and is put on hold at this point. Only when the radical species have a significant concentration of free molecules does termination occur successfully. As a result, there is a higher chance that molecules of radical acid may collide. There are no longer any free radical molecules as a result of the combination of all radical and free molecules. As a result, lipid peroxidation comes to an end.

Significance of Lipid Peroxidation

The realm of medical sciences recognises the significance of lipid peroxidation. It aids in the removal of tissues that contribute to malignancy, atherosclerosis, cancer, angina, and the ageing process in humans. Fundamentally, lipids serve as our body's energy sources while also assisting in the manufacturing of critical hormones. Lipids play a crucial role in the breakdown and assimilation of meals. For the retina and brain to function properly, a type of lipid peroxide called polyunsaturated fatty acids (PUFAs) is required. Their functions as immune system regulators, antioxidants, and anti-cancer agents are also significant. Lipid peroxide has the power to disable proteins, phospholipid-based cell membranes, immobilise enzymes, and immobilise proteins.

Interesting Facts

  • Fundamentally, lipids are our body's energy sources and the catalysts for the creation of critical hormones.

  • Lipids play a crucial role in the breakdown and assimilation of digested food.

  • Lipid peroxidation is a critical mechanism that occurs in both plants and mammals.

Important Questions

  1. State the significance of lipids.

Ans: Lipids are our body's primary source of energy, which fuels our systems and generates hormones. They make up the cell membrane's structural core. Additionally, these lipids have a role in food digestion and absorption, as well as cell signalling.

  1. Give an example of simple and complex lipids.

Ans: The example of Simple lipids are fat; complex lipids: phospholipids

Key Features

  • Hydrocarbons make up the majority of lipids.

  • Lipids that cannot be further broken down by the process of hydrolysis into simpler and smaller compounds are referred to as non-saponifiable lipids. Cholesterol, prostaglandins, and other lipids are some examples of non-saponifiable lipids.

  • Saponifiable lipids are lipids with many ester groups, which allows hydrolysis to further break them down into simpler and smaller molecules. Waxes, triglycerides, and other lipids are a few instances of saponifiable lipids.

Last updated date: 22nd Sep 2023
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FAQs on Lipid Peroxidation

1. What is lipid emulsion?

The technique of emulsifying the lipid substances that people can consume or administer intravenously is known as lipid emulsion. These also include intralipids, or emulsions comprising glycerine and phospholipids from eggs.

2. What components do lipids decompose into?

Triglycerides are broken down into fatty acids and monoglycerides during the digestion of lipids.

3. Which Enzyme Helps with Fat Digestion?

The majority of the body's digestive enzymes are water-based and capable of digesting both proteins and carbs. Lipases are specialised enzymes that break down lipids since they are not soluble in water and are digestive enzymes.