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Chemical Reaction: Age, Rage and Wrinkles
By: Steve Herman
Posted: August 26, 2008, from the September 2007 issue of GCI Magazine.
“Nature gives you the face you have at 20; it is up to you to merit the face you have at 50.” —Coco Chanel
The antiaging skin care juggernaut has crushed any lotion incapable of turning back the ravages of time, or at least promising to do so. The downside of UV exposure, smoking and pollution has long been known. Sugar formation in the cells, however, presents another front in the battle against aging. Chemically speaking, inside every cell, the Hayflick limit—the number of times a cell divides before it dies (approximately 50)—conspires against dreams of immortality. Receptor for advanced glycation end products (RAGE), too, is not simply the frustration of baby boomers with wrinkles—it is a new enemy of the intracellular matrix, and now it’s time to add the Maillard reaction, the Amadori product and collagen glycation to cosmetic chemists’ list of enemies.
French biochemist Louis-Camille Maillard (1878–1936) is the founding father of the most recent war on skin aging. In 1912, Maillard undertook studies of the reaction between amino acids and sugars, which now bear his name.
Food chemistry is a common part of everyone’s life and clearly illustrates the Maillard reaction. An egg white, for example, is not white before it is cooked. Heating denatures the protein, making it insoluble and, thus, changing it from clear to white. Raw meat is red, cooked meat is brown—and much tastier. The difference is primarily due to the Maillard reaction—the contribution of colors, flavors and odors—and it is where cooking and modern skin treatment find common ground.
The Maillard reaction starts when the carbonyl group of a sugar reacts with an amino group of a protein, producing N-substituted glycosylamine and water. Maillard reactions generally only begin to occur above 140°C (284°F). If the cooking temperature never gets above the boiling point of water (100°C or 212°F), the Maillard reactions will not take place. The resultant glycosylamine of the reaction is unstable and undergoes the Amadori rearrangement to form ketosamines. The formation of an advanced glycation end product begins with the formation of a Schiff base.