Overview of Peptides and Their Potential Roles in Skin Health and Beauty.

Peptides are molecules that consist of at least two amino acids linked by peptide bonds. The difference between peptides and proteins is primarily based on size and structure. Typically, oligopeptides consist of fewer than about 10-20 amino acids, and polypeptides consist of more than 20 amino acids, whereas proteins usually are made up more than 50 amino acids and often contain multiple peptide subunits as stated in the International Union of Pure and Applied Chemistry rules. Beyond the nutritional properties, peptides are also structural components of hormones, enzymes, toxins, and antibiotics and play several fundamental physiological roles in the body. Since the introduction of the first commercial peptide drug, insulin, peptide-based drugs have gained increased interest. So far, more than 80 peptide-based drugs have reached the market for a wide range of conditions, such as diabetes, cardiovascular diseases, and urological disorders. Meanwhile, peptides have also gained significant attention in the cosmetic industry because of their potential in boosting skin health. In this review, peptides were comprehensively summarized in the aspects of sources, function, the use of peptides in cosmetics and skin care, and indications for the delivery of cosmetic peptides.