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Chemical Reaction: Neurocosmetics
By: Steve Herman
Posted: May 4, 2007, from the May 2007 issue of GCI Magazine.
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Besides cooling, menthol type chemicals are reminiscent of peppermint candy, producing a tingle and possible burning sensation. The reaction varies in different parts of the body, being very strong on typically sensitive areas. The cooling compounds must penetrate the skin in order to interact with the receptors. For a more recent account of cooling chemistry, see Erman’s article3 in Cosmetics & Toiletries magazine. Erman cites sources attributing the hot and cold detectors as members of the transient receptor potential superfamily. Anyone interested in the detailed science of these proteins associated with cation-selective ion channels can find a good starting point with Huang4.
Moving past menthol, formulators are now looking at neurotrophins, a family of polypeptide growth factors. A key member is nerve growth factor (NGF), which is necessary for the survival of some classes of neurons—including some in the skin5. Tests show that brain-derived neurotrophic factors regulate some cutaneous mechanoreceptors. Since preservation of the neurocutaneous network is beneficial to the skin, this preservation is the logical focus of neurocosmetics.
NGF, like almost anything biochemical in nature, decreases with age. Acetylcholine, dopamine, adrenaline and serotonin are examples of neuroactive chemicals. Synthetically produced biomimetic peptides replicate a small, active amino acid sequence of neuromodulators and make them available in the dermis. Since dipeptides can be attacked by enzymes in the skin, decarboxylated dipeptides have been used to avoid enzyme destruction while maintaining biological activity similar to natural neuropeptides. The GT version has been commercialized under the INCI name “glutamylamidoethyl indole” by Exsymol S.A.M. This product is available in the United States through Biosil.
The N.V. Perricone M.D. brand utilizes Oligopeptide-17 (CLF-835 Neuropeptide). It is a 35 amino acid sequence claimed for CTFA listing to be a skin protectant. Lancôme Hydra Zen uses Acticalm, a combination of botanical and vegetal extracts. No reaction mechanisms are readily available in either of these products.
Soliance, available in the U.S. through Tri-K, markets Ocaline—a blend of seawater and pumpkin seed extract. Their Web site (www.groupesoliance.com) and literature proposes a mechanism of action. The pumpkin seed extract inhibits the action of neurotransmitter Substance P (as in “pain”). Under stress, Substance P is released from the nerve fibers of the skin, causing secretion of histamine from the mast cells, and leading to the typical signs of inflammation. If the activity of Substance P is inhibited, the skin becomes more resistant to attack.