Intro:
Capsaicin is an organic molecule that we use a lot in our society, even if we are not aware of it. Capsaicin is a naturally occurring organic molecule that is found in chilli peppers of the Capsicum family.
Capsaicin is also found within the spices: cinnamon, oregano and cilantro. This substance is the reason why these peppers and spices are spicy. It is part of the vanilloid family of molecules. That means that when we eat it, the capsaicin connects to a receptor on the tongue called the vanilloid receptor. When this happens, we get a burning feeling on our tongue. Capsaicin is also used for other things besides burning our mouths, for example medically or agriculturally.
History
Capsaicin was discovered by Christian Friedrich Bucholz in 1816.He was the one who named it capsaicin. But it was not made into its purest form until 1846 by John Clough Thresh. The name capsaicin came from the Greek word, kapto, which means “to bite”. Endre Hogyes was a doctor who discovered that capsaicin was what caused the burning sensation when it touched our skin or mouth. In 1919 the chemical structure of capsaicin was discovered by E.K. Nelson. And in 1930 a chemical synthesis was done to create capsaicin in a lab. That was done by E. Sparth and F.S. Darling.
How It Is Synthesized
Capsaicin is synthesized both biologically and commercially. There are 6 types of naturally produced capsaicin and only 1 type of capsaicin that is produced synthetically. We will start with biologically. It is made by chilli peppers in the Capsicum family as a secondary metabolite. That basically means that the capsaicin is not used for growth or reproduction, instead it is possible that it is used for defense against others that would eat the pepper. The creature would taste the spicy pepper and stop eating because it was too hot. Capsaicin was first synthesized in 1930 by Sparth and Darling. They synthesized capsaicin using these elements: they reacted isobutyl zinc iodide ethyladipyl chloride in cold toluene. This made the ester 8-methyl-nonan-6-on-1-ic acid. Then, they reduced the ester into 8-methylnonan-6-ol acid and then brominated to 8-methylnonan-6-bromo acid. The methyl ester of the new chemical was then dehydrobrominated by distillation in quinoline at 200-220°C to produce the methyl ester 8-methyl-6-nonan-1-ic acid. At this point it was an acid chloride. After they had reached this point they did saponification. That is a type of reaction with an animal fat or vegetable oil and a strong alkali, and some conversions that would make up the final step. The last step they did was to react the 8-methyl-6-nonenoyl chloride with vanillylamine in diethyl ether. This produced capsaicin. The capsaicin that they made was a mixture of structural and geometric isomers. Structural isomers have the same molecular formula but different structural formulas and geometric isomers have the same molecular and structural formulas.
Properties
Capsaicin’s form is a pure dark red solid. It has a strong and painful odour and a burning feeling to it when eaten or exposed to weak flesh. It’s molecular weight is 305.41 g/mol. The amount of capsaicin in peppers, where it is usually located, is measured using the Scoville Unit scale. The lowest pepper on the scale are bell peppers which are only rated from 0-100. The hottest pepper on the scale is the ghost pepper which ranges from 855,000 to 1,041,427. If we look past that we see that pepper spray is from 2,000,000 to 5,300,000. But capsaicin takes the cake because pure capsaicin is a 16,000,000, that is incredibly high and goes to show how painful this organic molecule can be to any sort of exposed flesh. Capsaicin also has very high melting points and boiling points. To boil capsaicin the temperature must be at 210°C and to melt capsaicin the temperature must be at 65°C. Capsaicin is not soluable in cold water. But it is soluble in warm or hot water. For it to be soluable in water is must be 0.0013 g/100 mL. Capsaicin is also soluble in petroleum, alcohol, oils, ether, benzene and slightly soluble in hydrochloric acid.
Uses in Society
Capsaicin has been used in society for hundreds of years and for many different purposes. It is one of the few pesticides in organic farming because when mammals eat it, it causes a burning sensation to the tissues, which keeps them from eating it again. The first organic pesticide using only capsaicin as the active ingredient was registered with the U.S. Department of Agriculture in 1962. However, birds have an intolerance to it. This is because they do not have the taste receptors that mammals do that cause calcium ions to enter neurons. This then irritates the neurons and causes the burning feeling when capsaicin is eaten. Another way that capsaicin is being used to help repel animals, is in paints. Capsaicin’s scent makes it so animals will not want be anywhere near the paint. The paint is then used on boats and municipal water systems to keep barnacles and zebra mussels from growing onto them. Fortunately, it is not harmful to the marine life, but it keeps them away due to the strong odour and taste. In some cases, people will use capsaicin and put it on cables to prevent rodents from chewing on it. Capsaicin is also the active ingredient in pepper sprays and bear attack deterrent sprays. When it is sprayed in the face of a mammal, it irritates the skin, eyes and respiratory airways which gives the burning feeling. Although it can be used to cause pain, capsaicin is also used to relieve it. One of the first people to discover this, was the Native Americans, who used it to relieve toothaches by rubbing peppers of the Capsicum family on their gums. Today, it can be used in the form of an ointment or cream to relieve pain from peripheral neuropathy which is where the nerves that connect the brain to the spinal cord are damaged. Also in an ointment or cream, it is used to relieve pain from muscle cramps, joint pain and some skin conditions such as arthritis.
Capsaicin works to relieve these pains because it overstimulates the nerves which then makes the nerves fatigued. When the nerves are fatigued, the pain impulse is no longer sent to the brain, so there is no more pain.
Probably the most common use for capsaicin, however, is to be used in foods in the form of peppers from the Capsicum family, to make it more spicy.
Problems
Capsaicin can be a very dangerous substance which means that there are many problems with it and many precautions to take when dealing with it. It is a light toxic substance but it can actually be fatal. The fatal dose for humans is between 0.5-5.0g for each kg of body weight when it’s in its pure form. Even if you eat a lot of peppers, hot sauce or some other food that contains capsaicin you could overdose. However, you would have to eat a lot of it. Capsaicin can also make foods mildly addictive because it excited the nervous system which then produces endorphins. These endorphins then give the person a feeling of well-being. But, this is not pure capsaicin. If someone does overdose on capsaicin, they would have difficulty breathing, convulsions, and a change in skin colour. If someone simply eats too much, they could experience nausea, vomiting, abdominal pain and/or burning diarrhea. Not only can capsaicin be painful if it’s ingested, it can also be painful if it comes in contact with any sort of tissue. Pure capsaicin can burn and blister the skin, even in a very small amount like 1 mg. This is why scientists will wear fully body protection when handling it. Peppers from the Capsicum family that contain capsaicin, will even cause irritation to the skin if you touch them. If you were to get capsaicin in your eye, it would cause intense tearing, and pain.
Conclusion
After all this information, we have proven that capsaicin is a very important molecule in society. If you got back pain, there’s capsaicin to help get on with your day. Need some spice in your life because your spouse isn’t doing that? Grab some capsaicin! But in all seriousness, capsaicin is used on a daily basis in terms of food like peppers, spices and sauces. Or as mentioned, it is used for medical purposes. For example it is used to help aid back pain. Capsaicin has been used for years and will continue to be used for years to come.
Sources: http://www.webmd.com/pain-management/tc/capsaicin-topic-overview#1
http://samgcapsaicin.weebly.com/history-of-capsaicin.html