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Peptides: Ready for Primetime?
By: Ahmed Abdullah, MD, FACS
Posted: June 28, 2011, from the July 2011 issue of Skin Inc. magazine.
During the past decade, peptides have taken on growing prominence in the skin care category. They’ve become so popular, in fact, that countless skin care products proudly feature them on their ingredient lists, whether sold by physicians and licensed skin care professionals, or department stores and drugstores. The excitement surrounding peptides isn’t simply reserved for product formulators and marketers, however. Take a look at the skin care conversation among consumers online, and you’ll find plenty of individuals pronouncing the positive impact peptide formulations have had on their skin. There’s little doubt that consumers are beginning to consider them the next big thing.
Yet, despite the vigor with which skin care brands promote peptide formulations and the growing consumer appetite for such products, their benefits have not yet been fully proven in the scientific arena. Certainly, potential exists, but so do limitations. Whether peptides truly are a panacea or simply another ingredient propelled into the spotlight may not yet be known for several years. Until then, it’s essential for skin care professionals to be well-versed on the topic, because, most certainly, your clients will soon be asking your opinion of peptides, if they haven’t already.
Peptides are biologically active compounds that closely resemble proteins—both are chains of amino acids. The difference? Peptide chains include fewer amino acids. Generally, a chain with more than 50 amino acids is a protein while those with fewer is a peptide. However, there are exceptions. Peptides are classified according to their length. Therefore, you’ll often encounter terms such as dipeptides—two amino acids; tripeptides—three; tetrapeptides—four; pentapeptides—five; and so on. Although there are probably thousands of naturally occurring peptides, to date, only several hundred have been characterized.1
Peptides play an array of important roles in the body, depending on the type. They may reduce inflammation, enhance antioxidant defense mechanisms, regulate bodily functions and even offer analgesic properties. In cosmeceuticals, three types of peptides are used, including:
- Signal peptides that encourage fibroblasts to increase production of collagen while decreasing the breakdown of existing collagen;
- Neurotransmitter peptides that limit muscle contraction and, thus, are said to mimic the effects of botulinum toxin; and
- Carrier peptides that stabilize and deliver trace elements necessary for wound-healing and enzymatic processes.
Given that signs of skin aging, including fine lines and wrinkles, are caused by a breakdown of collagen and elastin—the proteins that give skin strength and elasticity, as well as slow cellular turnover—the abilities of these peptides seem the perfect match for skin care formulations. However, not only are peptides expensive to utilize, in their natural state they also have shortcomings that significantly limit their potential in skin care applications. These shortcomings include the following.
- Peptides have a large molecular size and are hydropholic (water-liking), so they are unable to penetrate the lipopholic (fat-liking) stratum corneum layer of the epidermis.2 Despite this, peptides are generally unstable in water-based formulations. The presence of water breaks down the peptide bond, rendering it inactive.3
- Should peptides be absorbed, the abundant presence of enzymes found in the skin can also break down peptide bonds.4