https://www.mcgill.ca/oss/article/medical-did-you-know/there-much-pep-peptide-research Peptides are short chains of amino acids. But they come with a long story. Peptides are hot! Check the label of a skin care product and you are likely to come across a peptide. Read one of the numerous articles about Ozempic and you will discover that the active ingredient, semaglutide, is a peptide. Have a flagging libido? Kisspentin may be of help. It’s a peptide. The best place to start is always at the beginning. In this case that’s with an amino acid, a simple organic molecule with an amino group (NH2) at one end and an acid group (COOH) at the other. When the amino group of one molecule joins with the acid group of another, a new molecule that now is made up of two amino acids forms. This is known as a dipeptide. Three amino acids joined would be a tripeptide. More than twenty amino acids in a chain are termed a polypeptide and once fifty are exceeded we have a protein. These are not “hard” numbers in the sense that some may call a sequence of a hundred amino acids a polypeptide while to others it is a protein. Given that there are 20 common amino acids that can join together in various combinations, it is obvious that the number of peptides, polypeptides and proteins that are possible is virtually infinite. Peptides in the body have two sources. They can form when proteins break down, or they can be built from amino acids sourced from the diet. It has been estimated that there are about 7000 peptides present in the body at any time and while they have not all been identified, a significant number have been isolated and their function determined. Some serve as hormones, some as neurotransmitters, some play a role in digestion and metabolism, while others support the immune system, repair tissues, or serve as antioxidants. For example, insulin is the “gatekeeper” that allows glucose to enter cells, substance P is a peptide involved in pain transmission, endorphins dull pain and elevate mood, defensins kill bacteria, ghrelin stimulates hunger and leptin inhibits it. Once it became clear that peptides in the body have important functions, researchers began to wonder whether such molecules could be introduced into the body to serve a therapeutic role. After 1922 they no longer had to wonder. That was when insulin extracted from cattle pancreas was administered to Leonard Thompson, a 14-year-old diabetic, dropping his blood glucose levels to near normal. Since then a number of bioactive peptides have been isolated from natural sources or synthesized in the lab. Insulin itself is now produced by recombinant DNA technology that involves inserting the gene that codes for human insulin production into bacterial or yeast cells that will then grind out insulin. The peptide that is the basis of semaglutide (Ozempic) is produced using chemical reactions to link the component amino acids in the right sequence. The 9-amino acid peptide oxytocin is responsible for stimulating contractions during childbirth. It can be synthesized in the laboratory and is widely used to induce labour. Cyclosporin, a peptide that suppresses the immune system and prevents the rejection of transplanted organs was isolated from a fungus found in a soil sample in Norway. Ziconotide is a 25-amino acid peptide isolated from the venom of Conus magus, a sea snail. It has a painkilling potency a thousand times greater than morphine and is used for intractable cancer or neurological pain. Vancomycin, a glycopeptide, meaning it has a carbohydrate fraction attached to the chain of amino acids, was isolated from bacteria in a soil sample from the jungles of Borneo. It is an important antibiotic used to treat some infections that are resistant to the common antibiotics. Collagen peptides are widely promoted to reduce the effects of aging on the skin, but their efficacy is debatable. Collagen is a protein that is one of the main building blocks of skin and its production winds down with age resulting in wrinkles and sagging skin. The collagen peptides used in creams come from breaking down collagen sourced from the hides and connective tissues of cattle or pigs. The contention is that once these are absorbed, they will assemble to produce of collagen in the skin. Evidence for this is sketchy, but in any case, collagen peptides are effective moisturizing agents so they can improve the appearance of the skin. More troublesome are unregulated peptides such as sermorelin, sold in gyms or online that claim to stimulate the production of human growth hormone that in turn is supposed to help with muscle growth and repair. Another peptide that has been embraced by the fitness community is “body protection compound -157 (BPC-157),” a 15 amino acid chain that is said to help heal tendons and ligaments after an injury. Evidence provided comes mostly from animal studies and neither sermorelin nor BPC-157 are approved by FDA or Health Canada. Both are banned by the World Anti-Doping Agency. Peptide research is a very fertile area. Since 2000, some 30 peptide drugs have been approved for conditions ranging from multiple myeloma and erectile dysfunction to prostate cancer and osteoporosis. Dozens more are in clinical trials. An interesting one is “kisspentin,” so named because the gene that codes for it was discovered in Hershey, PA, the home of “Hershey’s Kisses.” The researchers who conducted two clinical trials, one in men and one in women with “hypoactive sexual desire disorder” concluded that “the administration of kisspentin has potential as a pharmacological treatment for low sexual desire.” The catch is that the kisspentin was administered intravenously for 75 minutes and the results were based on brain scans that monitored the response to erotic videos. That makes “potential for pharmacological treatment” seem somewhat optimistic. Maybe Hershey’s kisses would have the same effect. And they certainly don’t have to be administered intravenously.