Retinoid mimics and derivatives are currently hot ingredients that claim equal or better skin benefits than Retinol without having undesirable skin effects. Retinol is the best current OTC skin repair ingredient and the gold standard for treating the signs of aged skin based on published peer-reviewed studies (9,10, 11,12). Retinol is a precursor of Retinoic acid, which is an Rx ingredient approved to treat Acne and photodamaged skin. Once Retinol penetrates skin, it can oxidize to form Retinal then Retinoic acid. Most marketed products contain <0.1% Retinol due to excessive skin irritation and dryness. This irritation process is referred to as Retinization and typically will resolve after four weeks of use (25). Retinol can easily oxidize in formulations and lose efficacy. Retinol may also not be suitable for use by pregnant women since it is low-level teratogen.
Retinoid mimics, also referred to as Bio-Retinols, are ingredients that provide similar antiaging skin benefits to Retinol, Retinyl esters, and Retinoic acid without having the negative skin effects such as burning, stinging, redness, or dryness. They also typically have a better stability profile in formulations. Retinoid mimics are characterized by having a similar gene expression profile in upregulating genes associated with Retinol efficacy and upregulating many of the genes associated with an improved skin barrier. Some can also down regulate the expression of inflammatory cytokines such as IL-1A, IL-6, IL-8, COX-2, and MMP-1 known to contribute to Retinoid skin irritation. Retinoid mimics typically increase Retinol related efficacy genes such as CRAPP I/II (cellular binding proteins), RAR (retinoic acid receptors), RXR (retinoid X receptors), FGF (fibroblast growth factor), TGF (transforming growth factor beta) and can stimulate Collagen/Elastin/Hyaluronic acid formation.
Retinoid mimics/derivatives
- Bakuchiol is derived from the Psoralea Corylifolia plant which is common to India and Himalayan regions of Pakistan and China. It is a wild species that has been used in Ayurvedic and Chinese medicine for centuries to treat a variety of diseases. DNA array testing demonstrated a similar gene expression profile as Retinol (15). Bakuchiol was also clinically shown in a peer reviewed published study to be as effective as Retinol in treating aged skin. The results showed that after 12 weeks of treatment, a significant improvement in lines and wrinkles, pigmentation, elasticity, firmness was observed similar to Retinol but without having any negative skin effects (3). It also is claimed to be photochemically and hydrolytically stable making it suitable for daytime use. Bakuchiol is one of the most frequently searched active skin repair ingredients on the internet.
- Phytol is an acyclic diterpene alcohol that is a precursor for the manufacture of synthetic forms of vitamin E and vitamin K1. It also occurs naturally in the Bidens Pilosa plant and is a GRASE approved flavor ingredient. When applied to skin, Phytol is metabolized into Phytanic acid. Phytol and Phytanic acid have been reported to bind to and/or activate the PPAR-alpha and RXR receptors. In an 8-week placebo-controlled clinical study, a formulation containing 1% Phytol provided a statistically significant improvement in texture and fine lines and wrinkles versus a placebo control (8). Commercially available sources include Phytol Natural (Phytol-Vigon), MossCelltec No. 1 (Phytol (and) Isomalt (and) Aqua-Mibelle) and Revinage (Bidens Pilosa Extract, Elaeis Guineensis (Palm) Oil, Gossypium Herbaceum (Cotton) Seed Oil, Linum Usitatissimum (Linseed) Seed Oil-Chemyunion).
- In 2016 the FDA approved 0.1% Adapalene (Differin) as a once-daily topical gel for the over-the-counter (OTC) treatment of acne. Adapalene is a retinoid derivative that is less irritating and more stable then Retinoic acid (25). In published clinical studies, .3% Adapalene was shown to have similar efficacy as .05% Retinoic acid with less irritation in treating photoaged skin (26).
- Adapinoid (Oleyl Adapate-Actera) is an ester of Adapalene claimed to be an effective skin repair active with better stability and less irritation than Retinoic acid or Retinol (27).
- Hydroxypinacolone Retinoate is an ester of Retinoic acid claimed to be less irritating than Retinol. Supplier-sponsored clinical studies suggest similar skin repair efficacy as Retinol with better stability (28).
Retinoid efficacy boosters are ingredients that can be used together with Retinol to boost or maintain clinical efficacy while reducing negative skin effects.
- RonaCare Luremin (Sorbitol (and) Dihydroxy Methylchromone-EMD Performance Chemicals, DMC) is a naturally occurring flavonoid claimed to boost or maintain Retinol efficacy while allowing the use of lower concentrations of Retinol (1). In a placebo control 8-week double-blind clinical study, .1% DMC combined with .04% Retinol significantly reduced crow’s feet wrinkles more effectively than .1% DMC, .04% Retinol or .1% Retinol (13).
- Allosteris (Water (and) Glycerin (and) Glycine Soja (Soybean) Extract-Barnet Products) has been shown to increase stratum corneum cell turnover when combined with Retinol allowing for lower levels to be used. It is believed that increased cell turnover is one of the ways Retinol helps reduces fine lines and wrinkles. In a supplier sponsored study using .03% Retinol and 1% Allosteris, cell turnover increased 22% versus 6% using only 1% Allosteris, and 25% using .1% Retinol (13, 14).
- Bakuchiol can be combined with Retinol to reduce levels or boost efficacy It can also help stabilize Retinol (16).
- Ingredients that promote the conversion in skin of Retinol to Retinoic acid in skin may improve efficacy. Claimed ingredients include Quercetin, Geranyl Geraniol, hydroxy fatty acids, fatty acid amides, and imidazoles (Ketoconazole)(18).
- Chick pea extracts are claimed to boost retinoid efficacy (20).
- Anise seed extracts are claimed to boost retinoid efficacy (21).
- Mulberry extracts are claimed to boost retinoid efficacy (22).
Reducing Retinoid irritation
- A product containing Niacinamide and Retinyl Propionate had similar skin repair efficacy with better skin tolerance compared with using Retinoic acid alone (17). Another strategy to reduce irritation is to use a Niacinamide product for several weeks to build the skin’s barrier function before using a Retinol product.
- Borage seed oil a claimed as an anti-irritant in compositions containing hydroxy acids or retinoids (19).
- Trichodesma lanicum seed extract is an anti-irritant in compositions containing hydroxy acids or retinoids (22).
- An oat extract containing 100 ppm of Avenanthramides was shown to significantly reduce Retinol induced redness versus placebo (Dragocalm -Water, Glycerin, Avena Sativa (Oat) Kernel Extract-Symrise). The mechanism is reduced IL6 and 8 (24).
References
- http://iscd.it/files/Tiliroside-and-Dihydroxy-Methylchromone—from-Nature-to-Cosmetic-Applications.pdf
- https://www.scirp.org/pdf/JCDSA20120200002_59409694.pdf
- https://www.ulprospector.com/documents/1413479.pdf?bs=4702&b=220364&st=1&r=na&ind=personalcare
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4391488/
- US20030198657, Avon, 10/23/03, Methods using phytol to improve the appearance of skin and compositions for such method. Claims compositions containing Phytol and a retinoid.
- https://www.ulprospector.com/documents/1182076.pdf?bs=6823&b=237743&st=1&r=na&ind=personalcare
- https://www.ulprospector.com/documents/1570232.pdf?bs=2251&b=987004&st=1&r=na&ind=personalcare
- AAD poster-June 2017 Volume 76, Issue 6, Supplement 1, Page AB199
- https://www.neutrogenamd.com/sites/neutrogenahcp_us/files/pdf/2dot3_AgingSkin_PhysRes1_BellemereG.pdf
- https://onlinelibrary.wiley.com/doi/pdf/10.1111/jocd.12193
- https://pubmed.ncbi.nlm.nih.gov/27332694/
- https://jamanetwork.com/journals/jamadermatology/fullarticle/412795
- https://file.scirp.org/pdf/JCDSA20120200002_59409694.pdf
- Allosteris product presentation (Barnet Products)
- https://www.ulprospector.com/documents/1413479.pdf?bs=4702&b=220364&st=1&r=na&ind=personalcare
- https://www.ulprospector.com/documents/1413476.pdf?bs=4702&b=220364&st=1&r=na&ind=personalcare
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2841824/
- Unilever US patents 5583136, 5716627, 5747051, 5756109, 5665386, 8226933.
- Unilever US patent 59895572, 5690947
- Unilever US patent 6399083
- Unilever US patent 6395286
- Unilever US patent 6261566
- Unilever 5855893
- Symrise EP Application 1642566
- https://en.wikipedia.org/wiki/Adapalene
- https://www.jle.com/fr/revues/ejd/e-docs/comparable_efficacy_of_adapalene_0.3_gel_and_tretinoin_0.05_cream_as_treatment_for_cutaneous_photoaging_312613/article.phtml
- https://acteraingredients.com/products/adapinoid/
- https://www.ulprospector.com/en/na/PersonalCare/Detail/3030/5271090/SymRenew-HPR?st=1&sl=139403818&crit=a2V5d29yZDpbaHlkcm94eXBpbmFjb2xvbmUgcmV0aW5vYXRlIF0%3d&ss=2&k=hydroxypinacolone|retinoate|&t=hydroxypinacolone+retinoate+
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