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Cosmetic Chemistry and the Esthetician
By: Ivana Veljkovic, PhD
Posted: September 24, 2010, from the October 2010 issue of Skin Inc. magazine.
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Vitamin C. The only true, bioavailable form of vitamin C is L-ascorbic acid, although esters, such as ascorbyl palmitate, are often incorrectly referred to as vitamin C. When applied topically, L-ascorbic acid is able to stabilize and encourage the production of collagen. The additional antioxidant, anti-inflammatory and UV-protective benefits provided by L-ascorbic acid make it favorable for virtually all skin types and conditions.4–5
Peptides. All peptides are chains of amino acids. When applied topically, peptides are able to trigger specific functions within the skin. Although there are multiple topical peptide ingredients available, those used to treat visible aging have the most compelling studies backing their efficacy. Palmitoyl pentapeptide-4 stimulates types I and III collagen and dermal fibronectin; palmitoyl oligopeptide stimulates multiple dermal fibroblast production—including collagen; and acetyl hexapeptide-8 inhibits the repetitive motions that lead to dynamic wrinkling, such as crow’s-feet, frown lines and smile lines.6–8
Antioxidants. These substances prevent and reverse free radical damage, and many antioxidants offer more than one free radical-quenching benefit. L-ascorbic acid, resveratrol, tea polyphenols, vitamin E and glutathione act by donating electrons to unstable, damaged cells in the skin and body. Silybin (milk thistle), L-ascorbic acid and resveratrol offer additional benefits by chelating damaging metal ions from the affected cell. Finally, certain antioxidants, such as L-ascorbic acid, vitamin E and glutathione support, protect and regenerate one another, leading to sustained protection against oxidation. All skin types benefit from antioxidants.
A common question with skin care products is: What is the product’s delivery system? Although it is a valid question, it is more useful to understand when a delivery system is important. Certain active ingredients, such as retinoids and L-ascorbic acid, are typically more effective if a delivery system is employed. Delivery systems include ingredient encapsulation in lipids, microcapsules or liposomes, and micronization, which is formulating with very small ingredient particles. These delivery mechanisms are used to ensure a product’s active ingredients reach the level of the skin where they will provide the most benefit. Although delivery systems of this kind certainly have their place within the industry, most skin care products do not need them to be effective.
A product’s vehicle is most often what assists with product penetration. A vehicle refers to a product’s base, which is an emulsion, a suspension or a gel. Emulsions have a creamy consistency and are formulated to ensure the active ingredient is evenly distributed throughout the product. Emulsions combine water-soluble and oil-soluble ingredients, leading to penetration into both the skin’s aqueous and lipid environments. In some cases, thick creams can impede active ingredient penetration, because traveling through the product’s base itself requires a significant amount of a molecule’s energy. For this reason, emulsions are typically better suited for moisturizers, versus corrective topicals.