Capsaicin in chili peppers is mainly found in the placenta tissue (the part of the chili pepper where the seeds are attached) of the chili pepper pulp cells.

The pungent constituents in chili peppers are mainly composed of a series of substances that are very similar in structure and properties, collectively known as capsaicinoids, of which the most important is capsaicin (69%), followed by dihydrocapsaicin (22%). Capsaicin is synthesized in the placenta tissue of the chili pepper fruit (the part to which the chili pepper seeds are attached), so the content of capsaicin here is also the highest, followed by the fleshy part of the chili pepper, and the content in the chili pepper seeds is instead very low.

Nociceptors called TRPV1 are present in humans in areas such as the mouth and skin, where they are activated by acidic solutions with a p H value of less than 6, substances above 45 degrees Celsius, and specific molecules associated with inflammation, and produce pain. Interestingly, substances such as capsaicin in chili peppers, piperine in peppers, and mustard oil in white carrot skins also activate TRPV1, which causes us to feel pain. Although capsaicin doesn't directly damage body cells, it works through the TRPV1 receptor to give the brain the illusion that it is being burned.

The Effects of Cayenne Peppers

You may notice that when you eat a lot of spicy food, the fiery sensation of the initial meal diminishes because that's when the receptor no longer reacts as strongly to capsaicin. This phenomenon is known as capsaicin desensitization, and the mechanism behind it has long attracted the attention of scientists. In the course of their explorations scientists have discovered that capsaicin can actually relieve pain.

Substance P is a neurotransmitter, without which nerve cells would not be able to transmit pain signals to the brain. in 1979, scientists found that repeated use of capsaicin concentrate on subjects quickly depleted their bodies of Substance P, making it difficult for the subjects to feel pain. Many people with diabetes develop pain in their toes due to neuropathy. Clinical trials have shown that applying capsaicin ointment to the affected area is effective in relieving pain in these patients.