Squalene

Squalene is a clear oil.

It is found in many living things. Plants and animals make it. It is even in human skin. It helps keep skin soft.

This oil helps the body make things. It helps make parts of our cells. It also helps make hormones.

Some medicines use this oil. It helps a vaccine work better. It helps the body learn to fight germs.

Scientists can make this oil in labs. They use tiny yeast to do it. This helps keep sharks safe in the sea.

Squalene is a clear oil.

It is found in many living things. Most plants and animals make it. It is even in human skin. About 12% of the oil in human skin is squalene. This oil helps keep skin soft and protected.

This oil helps the body make other things. It is a precursor, which means it is a starting part. It helps make cholesterol. It also helps make steroid hormones. In many bacteria, it helps make hopanoids. These are parts used by the tiny cells.

Squalene is also used in some vaccines. It can act as an adjuvant. An adjuvant is a substance that helps a vaccine work better. It helps the body's immune system respond to the medicine. One type of flu vaccine uses it. This helps the body make special cells to fight germs.

Long ago, people got squalene from shark liver oil. This caused worry for people who protect sharks. Now, scientists make squalene in labs. They use yeast or bacteria to make it. This way keeps sharks safe in the ocean.

Squalene is a clear oil that lives in many parts of nature. It is a special type of organic compound called a triterpene. This oil is found in many plants, fungi, and animals. Even humans have it in their own bodies. About 12% of the sebum in human skin is made of squalene. This oil helps to lubricate and protect our skin.

In nature, squalene works as a starting part for making other things. This is called a biochemical precursor. For example, it helps make sterols like cholesterol in humans. The process begins when an enzyme changes one part of the squalene. This creates a new substance called 2,3-oxidosqualene. Then, another enzyme helps turn it into lanosterol. This can eventually become things like ergosterol in fungi or stigmasterol in plants.

Scientists have learned a lot about how to get this oil. Originally, people got squalene from the liver oil of sharks. The name actually comes from the shark genus called Squalus. In the 1990s, researchers at Ciba-Geigy and Chiron worked on using it in medicine. These companies were later bought by Novartis. Today, we can also make squalene in labs. We can use genetically engineered yeast or bacteria to grow it. This helps protect sharks from being hunted.

Squalene is very important for making some vaccines work better. It is used as an adjuvant, which is a substance that helps the immune system. An adjuvant like MF59 helps a vaccine trigger a stronger response. This specific type is used in some influenza vaccines. It helps the body produce CD4 memory cells to fight germs. The FLUAD vaccine uses this and was approved in the US in 2016. It is meant for people who are 65 years of age or older.

Many people wonder if squalene is safe to use. Studies show it has low toxicity when used in cosmetics. It does not usually cause skin irritation or allergies. The World Health Organization has shared reports on its safety. They noted that squalene is found naturally in things like human fingerprints. In Europe, over 22 million flu vaccines with squalene have been given since 1997. These vaccines did not cause major problems for the people who took them.

Squalene is a specific type of organic compound known as a triterpene. It has the chemical formula C30H50. In its pure form, it is a colorless oil. However, samples that are not pure often appear yellow. This substance is found throughout the natural world in many different forms. Most plants, fungi, and animals produce it through biological processes. It even exists within the human body. For example, about 12% of the sebum, or skin oil, in humans is made of squalene. This oil plays a vital role in lubricating and protecting the skin.

Squalene acts as a biochemical precursor in many different systems. A precursor is a starting molecule that helps build more complex substances. In many bacteria, squalene is an intermediate used to make hopanoids. In many eukaryotes, which are complex organisms, it is used to build sterols. The process for making sterols begins with a specific chemical change called oxidation. An enzyme called squalene monooxygenase acts on one of the terminal double bonds of the squalene molecule. This reaction creates a new substance called 2,3-oxidosqualene.

From there, the molecule undergoes a process called enzyme-catalyzed cyclization. This means an enzyme helps the molecule fold into a ring shape to create lanosterol. Lanosterol is a key building block for many other steroids. Through a multistep process, lanosterol can be changed into cholesterol or steroid hormones in humans. This process involves removing three methyl groups and moving a double bond. It also involves the reduction of another double bond using NADPH. In many plants, this pathway leads to the creation of stigmasterol. In many fungi, the pathway produces ergosterol.

Nature produces squalene through a process called biosynthesis. This happens when two molecules of farnesyl pyrophosphate are coupled together. This condensation process requires a specific enzyme called squalene synthase and a substance called NADPH. While nature uses these biological paths, humans have learned to produce squalene in other ways. Commercially, synthetic squalene can be prepared from a substance called geranylacetone. Scientists also use genetically engineered yeast or bacteria to grow it. This modern method is important for conservation efforts.

Historically, squalene was obtained from the liver oil of sharks. Its name comes from the shark genus known as Squalus. However, using shark oil has caused significant environmental concerns. In 2020, conservationists worried that sharks might be slaughtered to obtain squalene for COVID-19 vaccines. Because of these concerns, researchers moved toward using other sources. This shift helps protect shark populations while still providing the oil needed for medicine and industry.

Squalene is also a key ingredient in certain vaccine adjuvants. An adjuvant is a substance added to a vaccine to stimulate the immune system. While squalene is not an adjuvant by itself, it is used with surfactants in special formulations. One famous example is the MF59 adjuvant, which was developed in the 1990s. Researchers at Ciba-Geigy and Chiron originally developed it. These companies were later acquired by Novartis. Today, the influenza vaccine business of Novartis is managed by a company called Seqirus.

MF59 is used in influenza vaccines to make them more immunogenic. This means it helps the vaccine create a stronger immune response. Specifically, it helps the body produce CD4 memory cells. The FLUAD vaccine, which uses MF59, was approved in the United States for people aged 65 and older starting in the 2016–2017 season. Scientists are still studying exactly how MF59 works. They do not yet know the exact mechanism of action or which receptors it responds to. One theory is that it changes lipid metabolism by causing cells to accumulate neutral lipids.

Safety is a major topic regarding the use of squalene. Toxicology studies show that squalene has low acute toxicity in cosmetic concentrations. It is generally not a significant irritant or allergen for the skin. The World Health Organization has noted that squalene is naturally occurring in things like human fingerprints. Since 1997, over 22 million flu vaccines containing squalene have been used in Europe. These vaccines have not been linked to significant adverse events. Additionally, scientific studies have debunked attempts to link squalene to Gulf War syndrome.