Wrinkle Repair Kit

Everyone’s skin is different but for those with sensitive skin, this combination is tough to tolerate particularly in the initial months when your skin is getting acclimated to the increased cell turnover. While both Moonlight and the Night Renewer are designed for sensitive skin and have skin soothing, calming, and hydrating ingredients, both also contain high concentrations of potent actives that can be irritating. While many will have no problem using both these products together every day starting from day 1, those with more sensitive skin will struggle to do so and experience a high level of irritation, peeling, and redness.

In this case, we suggest you slowly introduce these actives into your nighttime routine one at a time starting with just Moonlight 2-3 times a week. When introducing a retinoid into a skincare routine, you may experience some skin dryness and skin peeling in the first few weeks.

After this acclimation period is over, add in Night Renewer to your nighttime routine on alternating nights with Moonlight.
In other words, use Moonlight combined with another moisturizer on one night, and then skip Moonlight and use Night Renewer on the next night. This alternating regimen will still provide benefits as long as it is used consistently long-term.

Since glycolic acid creams will increase the sun sensitivity of the skin, the Night Renewer should be used only at night, and paired with a broad-spectrum sunscreen with an SPF of at least 30 during the day. Retinoids can also increase sun sensitivity in the initial stages, and further, are sensitive to degradation when exposed to light. This is why Moonlight should also be used only at night (Kaidbey et al. 2003, Mukherjee et al. 2006).

We recommend using Glow Maker serum and sunscreen in the morning as both contribute to protection against UV damage. A good broad-spectrum SPF is one of the most important things you can do to prevent skin from photoaging. However, even good sunscreens only block about half of the free radicals spawned from UV exposure. Antioxidant vitamin C serums help neutralize free radicals to protect your skin from harmful UV rays. As vitamin C in the skin is quickly depleted by fighting UV damage or other free radical generating activities such as smoke and pollution throughout the day, topical vitamin C application twice a day may be useful to replenish levels when engaged in outdoors activities. Topical vitamin C and sunscreen work by differing mechanisms to protect your skin so the combination is ideal (Lin et al. 2005, Telang et al. 2013).

The most important anti-aging aspect of topical vitamin C (l-ascorbic acid) is its role as one of nature’s best antioxidants and indeed, one of the primary defenses against UV damage employed by the skin. Under normal conditions, special receptors in the skin pull vitamin C out of your bloodstream to pack your skin full of this protective antioxidant which is also the most plentiful antioxidant in the skin (Pullar et al. 2017). The number one cause of premature aging of the skin is UV damage from the sun’s rays. When your skin is exposed to UV rays, free radicals are spawned. These free radicals are like ricocheting bullets tearing up collagen and even DNA leading to photo-aged skin and skin cancers. Fine lines and wrinkles, sunspots, ruptured blood vessels, enlarged pores, and rough coarse skin are some of the features of photo-aged skin.

Unfortunately, like so many processes that occur with general aging, the vitamin C content in your skin wanes as you age irrespective of diet, as poor blood flow and nutrient delivery start to affect levels. In other words, your natural defenses against UV damage go down with aging. This is where topical supplementation can remedy the situation as the skin absorbs the vitamin C applied at the skin’s surface (Pullar et al. 2017).

A second reason vitamin C is such an excellent anti-aging ingredient is that it boosts collagen production. Collagen is the main structural protein in the skin and its decline and degradation are the main drivers of fine lines and wrinkles. The collagen content in skin decreases over time – roughly 1% per year with accelerated loss post-menopause – leading to wrinkles and sagging as we get older. vitamin C is necessary in collagen production. The ability of topical vitamin C to boost collagen production has been demonstrated in placebo-controlled trials of aged skin in postmenopausal women (Nusgens et al. 2001) and in those with photoaged skin (Traikovitch 1999). Note that the role of vitamin C in collagen production is also responsible for its beneficial role in wound healing and for the skin symptoms of scurvy which results from vitamin C deficiency (Pullar et al. 2017).

When speaking about anti-aging ingredients, the number one spot is always taken by retinoids such as retinol, retinal, and tretinoin. Of the three, retinal has the best trade-off between potency and irritation. It is almost as potent as tretinoin which is 10-20 times stronger than retinol at the same concentration, while being less irritating that both at matched potency.

Retinoids are well-studied vitamin A related compounds. Retinoids address most of the issues surrounding aging skin. With aging, the skin gets less blood flow (less vascularized), becomes thinner and more lax, and finely lined. Additional photo-aging from sun damage results in hyperpigmentation spots, rough patches (actinic keratosis), enlarged pores and deep wrinkles. Topical retinoids have been scientifically shown to help treat every one of these issues because they act on nuclear receptors that regular the activation of many genes in a wide variety of cell types (Mukherjee et al. 2006).

First, retinoids increase blood flow to the skin by increasing endothelial cell proliferation leading to increased vascularity. Second, it thickens the epidermal layer of skin by upregulating the proliferation of skin cells (keratinocytes). Third, it reduces fine lines and wrinkles by upregulating collagen production and other components of the extracellular matrix (ECM) including elastin, fibronectin and glycosaminoglycans (GAGs). It does so by increasing dermal fibroblast activity and decreasing collagenase production. Fourth, retinoids can improve hyperpigmentation and the appearance of pore size by inhibiting melanosome transfer to keratinocytes from melanocytes, and accelerating cell turnover. These patterns of results have been replicated in study after study in aged skin and photoaged skin (Saurat et al. 1994, Kafi et al. 2007, Kong et al. 2015, Shao et al. 2017, Bouloc et al. 2014, Creidi et al. 1998, Leydon et al. 2017, Zasada and Budzisz 2019).

Complete skin (epidermal) renewal occurs approximately every 28 days in young adults, while the same process takes 40 to 60 days in older people. This accumulated layer of dead skin makes the skin look rougher and the pores look more enlarged. Light reflecting on the skin also reveals a dull surface (Rodan et al. 2016). By chemically exfoliating these dead cells with hydroxy acids, one can immediately reveal smoother, brighter, and younger looking skin. Regular sloughing off of dead skin cells can also encourage faster turnover of the underlying skin cells, which again mimics the renewal process in younger skin (Kornhauser et al. 2010).

A 10% concentration of glycolic acid is the upper allowable limit for cosmetic products as regulated by the FDA. At this concentration, glycolic acid creams can be safely used and with good tolerability (Abels et al. 2011). Further 10% glycolic acid creams can be used daily, and will serve as a powerful chemical exfoliant which will improve skin texture, the appearance of lines and wrinkles. and fade hyperpigmentation over a long time. This is because the increased cell turnover will help slough off hyperpigmented skin and rapidly disperse existing pigment which helps to fade the appearance of hyperpigmentation (Kornhauser et al. 2012). Hence, a glycolic acid cream is a helpful adjunct to use along with serums that treat hyperpigmentation by quickening the process by which hyperpigmented spots are sloughed off.

Chemical peels use a much higher concentration of glycolic acid up to 40%. These should not be done at home and should only be used 1 or 2 times annually. Chemical peels chew through living tissue as well as dead skin cells, and so while they may be able to fade deep pigmentation and remove deep imperfections in the skin. However, they also may lead to scarring and require a longer healing time (Arif 2015, Chilicka et al. 2020, Garg et al. 2009, Sharad 2018).

In addition to exfoliation, 10% glycolic acid can have other benefits as well. Though not typically thought of as a collagen booster, glycolic acid can activate underlying cellular processes that accelerate collagen synthesis by fibroblasts, and modulate matrix degradation through keratinocyte released cytokines (Okano et al. 2003). This collagen building ability was found to increase with increasing concentrations of glycolic acid all while avoiding triggering inflammation when kept at a pH of 4 or higher (Narda et al. 2020). In sun-damaged skin, glycolic acid was found to increase hyaluronic acid content in the epidermis and dermis as well as increasing collagen synthesis and epidermal thickness (Bernstein et al. 2001). In other words, glycolic acid creams are a helpful adjunct to use along with other more powerful anti-aging ingredients such as retinoids to aid in the collagen building process.

Ideally when treating hyperpigmentation and dark spots, a combinatory approach is recommended. For example, it has been scientifically shown that combinations of retinoids with ‘depigmenting agents’ such as hydroquinone or arbutin, or with vitamin C, or with glycolic acid works better than any of these agents used alone (Mukherjee et al. 2006). This anti-aging kit contain a retinoid (retinal in Moonlight), vitamin C (in Glow Maker), and glycolic acid (Night Renewer) to help target dark spots and generally even out skin tone.

Our hyperpigmentation specialist (Fade Away serum) is not included in this kit and contains a trio of depigmenting agents that are hydroquinone alternatives. This serum can be added to this routine for more intensive treatment of hyperpigmentation in those for whom dark spots are a primary concern.

Retinoids even out skin tone by inhibiting melanosome (think sacs that contain melanin) transfer to keratinocytes (skin cells) from melanocytes (cells that make melanin). They also help accelerate the rate at which your skin cells renew allowing dark spots to fade faster (Leydon et al. 2017, Zasada and Budzisz 2019). Vitamin C can not only fight UV damage which is a main cause of hyperpigmentation, but also can inhibit an enzyme (tyrosinase) involved in skin pigment production. A concentration of at least 10% Ascorbic acid is recommended to get maximal benefits against UV induced hyperpigmentation (DeDormeal et al. 2019). Glycolic acid can exfoliate and increase cell turnover which will help slough off hyperpigmented skin and rapidly disperse existing pigment which helps to fade the appearance of hyperpigmentation (Kornhauser et al. 2012).

Products such as the 10% glycolic acid cream Night Renewer will have immediate visible results starting from the very first day after overnight usage. These benefits include a smooth and radiant complexion. Longer term changes to underlying skin take longer to develop and may take weeks to months.

For high potency retinoid products such as Moonlight, though these products start working right away at the cellular level, it takes a while to see a visible difference in fine lines and wrinkles. With special equipment, significant changes underneath the skin can be measured and visualized after just seven days. However, in order for there to be a noticeable difference in the appearance of wrinkles and overall skin texture with the naked eye, it typically takes four to six weeks.

For vitamin C, scientific studies show that the skin will absorb (L-Ascorbic Acid) optimally from a serum when the concentration is between 10-20% Ascorbic Acid. At these concentrations, it reaches saturation after 3 days of consistent daily application (Pinnel et al. 2001). Hence, after 3 days of consistent daily application of Glow Maker, vitamin C levels will reach saturation and begin to provide optimal protection to your skin.

This anti-aging kit covers the basics that will get you visible results with a simple routine that includes a serum for the morning, a serum for the evening, and a cream for the evening. For those who want to really maximize anti-aging actives and are willing to have a slightly more built out routine, we recommend the following:

Adding Peptide Squad collagen renewal serum to your routine will let you take advantage of all four classes of wrinkle-fighting peptides that will really kick-start collagen renewal and inhibit expression lines. This includes signal peptides (Matrixyl 3000), copper peptides (GHK-Cu), neurotransmitter inhibiting peptides (Argireline), and enzyme inhibitor peptides (rice peptides). Hydro Relief cream additionally contains soy peptides and amino acids that have hydrating and anti-aging benefits.

Along with vitamin C, retinoids and glycolic acid, niacinamide (vitamin B3) is one of the most proven, tried and true anti-aging actives. Several Maelove products incorporate this versatile ingredient. NIA 10 Calming Serum contains 10% niacinamide, and is considered our niacinamide booster serum. Peptide Squad also incorporates niacinamide into your routine, as well as our moisturizers Hydro Relief and Plush Cream. You do not need all of these products, but it is a good idea to incorporate at least one product in your routine that contains niacinamide.

Adding Fade Away Brightening Serum to your routine is advisable if you have dark spots that are one of your primary concerns. It is our hyperpigmentation specialist and contains a trio of depigmenting agents that are hydroquinone alternatives. This trio (alpha-arbutin, kojic acid, licorice root extract) are tyrosinase inhibitors that inhibit the production of melanin from overactive melanocytes. It also contains glutathione, red algae, and a host of botanical extracts that represent antioxidant and anti-inflammatory actives that help to prevent further hyperpigmentation at its source. This serum can be added to this anti-aging kit for more intensive treatment of hyperpigmentation.

Adding Eye Enhancer De-Puffing Peptide cream can help reduce the dark circles and puffy eye bags underneath your eyes, as well as reduce the expression lines around your eyes. It includes peptides Eyeseryl and Argireline as well as caffeine to specifically target these concerns.

Finally, it is highly advisable to always wear sunscreen during the day. A broad-spectrum SPF 30 product is recommended by the AAD. The Sun Protector is a 100% mineral broad-spectrum SPF 30 sunscreen.

The Glow Maker and The Night Renewer can both be used while pregnant or lactating.

However, do not use Moonlight while pregnant or lactating. Topical Retinoids are deemed unsafe to use while pregnant due to risk of birth defects from systemic absorption, i.e. your bloodstream. If you are pregnant or lactating, we recommend using the Peptide Squad serum in lieu of Moonlight.

Always double check ingredients with your doctor and follow their protocol.If you want to learn more, please check out this newsletter.

Peptides are generating quite a buzz in the skincare world these days, and for good reason! However, it’s crucial to understand that peptides are a diverse group of molecules, and not all of them are backed by solid scientific evidence.

It took us a year and a half of rigorous research and investigation to pinpoint the best peptides and perfect the formulation. What we discovered is game-changing: combining peptides with solid scientific backing from four distinct classes can genuinely improve the health and appearance of your skin. The beauty of Peptide Squad lies in its balanced formulation. By utilizing a full range of peptides, and co-formulating with the perfect supporting cast, we are able to deliver comprehensive skin benefits in a product that feels really great to apply.

Neurotransmitter inhibiting peptides are sometimes informally called “botox-like” or a botox alternative, though this descriptor is disliked by dermatologists. Nonetheless, the principles behind these peptides are similar to that of botox in that they aim to act on the cholinergic neuromuscular junction to inhibit muscle activity and in this manner, limit wrinkle formation. For neurotransmitter acetylcholine to be released, a reaction cascade mediated by SNAP receptor proteins and SNARE complex formation is necessary. SNAP-25 specifically is targeted by both botulinum neurotoxin type A (botox) and the peptide included here, ArgirelineR. ArgirelineR competes with the SNARE complex by mimicking the N terminal end of SNAP-25 – hence preventing formation of the SNARE protein complex and inhibiting acetylcholine release and subsequent muscle contraction (Lipotec Argireline).

Argireline (also known as acetyl hexapeptide-8 or acetyl hexapeptide-3) has been shown to have an anti-wrinkle effect (Blanes-Mira et al. 2002, Draelos et al 2016). It has lower efficacy than botox itself but is a safe, non-toxic alternative (Blanes-Mira et al. 2002). Published clinical studies show its anti-wrinkle efficacy whether formulated alone (Blanes-Mira et al. 2002, Tadini et al. 2015) or in a mix of peptides (Draelos et al. 2016, Errante et al. 2020). Interestingly, a double-blind study using topical Argireline cream in patients receiving botox treatment for blepharospasm saw an extension of botox benefits to symptom control when using the cream, suggesting topical Argireline can also increase the length of botox benefits (Lungu et al. 2013). Clinical studies conducted by the manufacturer also demonstrate reduced eye wrinkle depth and volume with usage of Argireline creams (Lipotec Argireline).

Encapsulation is a technique used in skincare and may be used for many reasons, including protection of a reactive or unstable ingredient from degradation or reacting with other ingredients. Peptides are generally not reactive nor unstable. However, some may opt to use encapsulated copper peptides in the belief that this protects the potential free copper which is a pro-oxidant from interactions with Vitamin C which is an antioxidant. We do not advise our customers to use encapsulated copper peptides at this time, mainly because the available encapsulated copper peptides on the market are not the tried and true Cu-GHK but rather, Copper Palmitoyl Heptapeptide-14. There are no published scientific reports on this ingredient outside of the supplier. In other words, the encapsulated version may no longer have all of the skin beneficial effects long described in scientific literature for Cu-GHK. Further, if this ingredient results in free copper, then encapsulating that free copper would allow it to penetrate into the skin and oxidize the lipids and proteins in the skin which is damaging. It would be preferable to neutralize a Vitamin C serum rather than fo

Further he encapsulated lipopeptide (Copper Palmitoyl Heptapeptide-14) is no longer the long-studied copper tripeptide-1 (Cu-GHK) that has been researched and used successfully in skin-care and wound healing products for decades. No such published studies are available for encapsulated copper peptides outside of the manufacturer that can claim the same.

Finally, as an added precaution, Peptide Squad contains a metal chelator which removes any potential free copper from the serum solution (Chiou et al. 1985). Note that we can not vouch for other peptide serums as to whether or not they have taken the proper precautions.

In your skin, the safe delivery of copper is trusted to GHK-Cu. GHK-Cu is like riding with a chauffeur you have trusted all the years of your life. Whereas, other copper peptides are like hitch-hiking a ride with a stranger. The risk isn’t worth it.

Not all copper is good copper. With the wrong carrier, copper can cause both damage to cells and inflammation (Li et al. 2016, Pickart et al. 2015). In fact, Cu-GHK is often unique in studies when compared to other copper compounds. One study looked at conjugated copper in the form of Cu-GHK versus other copper compounds and only Cu-GHK did not stimulate an inflammatory action nor toxicity to skin cells (Li et al. 2016). Hence with less studied copper compounds, there is a lot that can go wrong including harm to skin. So with these encapsulated copper peptides, because they are not Cu-GHK, you have no certainty about whether or not they may actually have harmful effects or generate free copper ions.

We believe the secret to a good copper peptide serum is to make sure it has no free copper ions, not to encapsulate these potential free copper ions so that they can be delivered inside your skin to wreak extra havoc.

Our advice: stick with the tried and true Cu-GHK

Yes. The actives in Peptide Squad including peptides, niacinamide, panthenol, hyaluronic acid, natural moisturizing factors, ceramides and jojoba and botanical extracts and actives including allantoin, aloe, green tea, turmeric and polyphenols such as madecassoside (found in CICA) and bisabolol (found in chamomile) are all considered generally safe to use topically during pregnancy and lactation.

However, it is always advisable to check with your doctor regarding skin care products and ingredients and follow their protocol.

Kaidbey K, Sutherland B, Bennett P, Wamer WG, Barton C, Dennis D, Kornhauser A (2003). “Topical glycolic acid enhances photodamage by ultraviolet light.” Photodermatology, Photoimmunology & Photomedicine 19(1): 21-27.

Lin FH, Lin JY, Gupta RD, Tournas JA, Burch JA, Selim MA, Monteiro-Riviere NA, Grichik JM, Zielinski J, Pinnell SR (2005). “Ferulic Acid Stabilizes a Solution of Vitamins C and E and Doubles its Photoprotection of Skin.” J Invest Dermatol 125:826-832
Mukherjee S, Date A, Patravale V, Korting HC, Roeder A, Weindl G (2006). “Retinoids in the treatment of skin aging: an overview of clinical efficacy and safety.” Clinical Interventions in Aging. 1(4) 327-348.

Telang PS (2013). “Vitamin C in Dermatology.” Indian Dermatol Online J. 4(2): 143-146.

Nusgens BV, Humbert P, Rougier A, Colige AC, Haftek M, Lambert CA, Richard A, Creidi P, Lapiere CM (2001). “Topically Applied Vitamin C Enhances them RNA Level of Collagens I and III, Their Processing Enzymes and Tissue Inhibitor of Matrix Metalloproteinase 1 in the Human Dermis.” J Investig Dermatol 116(6): 853-859.

Pullar JM, Carr AC, Vissers MCM (2017). “The Roles of Vitamin C in Skin Health.” Nutrients. 9:866. doi:10.3390/nu9080866

Traikovich SS (1999). “Use of Topical Ascorbic Acid and Its Effects on Photodamaged Skin Topography.” Arch Otolaryngol Head Neck Surg 125:1091-1098.

Bouloc A, Vergnanini AL, Issa MC (2014). “A double-blind randomized study comparison the association of Retinol and LR2412 with tretinoin 0.025% in photoaged skin.” J Cosmetic Dermatol, 14, 40-46.

Creidi P, Vienne MP, Ochonisky S, Lauze C, Turlier V, Lagarde JM, Dupuy P (1998). “Profilometric evaluation of photodamage after topical retinalydehyde and retinoic acid treatment.” J Am Acad Dermatol 39: 960-965.

Kafi R, Kwak HSR, Schumacher WE, Cho S, Hanft VN, Hamilton TA, King AL, Neal JD, Varani J, Fisher GJ, Voorhees JJ, Kang S (2007). “Improvement of Naturally Aged Skin with Vitamin A (Retinol)” Arch Dermatol 143: 606-612.

Kong R, Cui Y, Fisher GJ, Wang X, Chen Y, Schneider LM, Majmudar G (2015). “A comparative study of the effects of retinol and retinoic acid on histological, molecular, and clinical properties of human skin.” J Cosmetic Dermatol 15: 49-57.
Leydon J, Stein-Gold L, Weiss J (2017). “Why topical retinoids are mainstay of therapy for acne.” Dermatol Ther (Heidelb) 7: 293-304.
Mukherjee S, Date A, Patravale V, Korting HC, Roeder A, Weindl G (2006). “Retinoids in the treatment of skin aging: an overview of clinical efficacy and safety.” Clinical Interventions in Aging. 1(4) 327-348.

Saurat JH, Didierjean L, Masgrau E, Piletta PA, Jaconi S, Chatellard-Gruaz D, Gumowski D, Masouye I, Salomon D, Siegenthaler G (1994). “Topical Retinaldehyde on Human Skin: Biologic Effects and Tolerance.” J Invest Dermatol 103:770-774.

Shao Y, He T, Fisher GJ, Voorhees JJ, Quan T (2017). “Molecular basis of retinol anti-aging properties in naturally aged human skin in vivo.” Int J Cosmet Sci. 39(1): 56-65.

Zasada M and Budzisz E (2019). “Retinoids: active molecules influencing skin structure formation in cosmetic and dermatological treatments.” Adv Dermatol Allergol XXXVI(4): 392-397.

Abels C, Kaszuba A, Michalak I, Werdier D, Knie U, Kaszuba A (2011). “A 10% glycolic acid containing oil-in-water emulsion improves mild acne: a randomized double-blind placebo-controlled trial.” J Cosmet Dermatol 10(3): 202-209.

Arif T (2015). “Salicylic acid as a peeling agent: a comprehensive review.” Clinical, Cosmetic and Investigational Dermatology 8:455-461.

Bernstein EF, Lee J, Brown DB, Yu R, van SE (2001). “Glycolic acid treatment increases type I collagen mRNA and hyaluronic acid content of human skin.” Dermatol Surg 27(5): 429–433.

Chilicka K, Rogowska AM, Szygula R, Taradaj J (2020). “Examining Quality of Life after Treatment with Azelaic and Pyruvic Acid Peels in Women with Acne Vulgaris.” Clinical, Cosmetic and Investigational Dermatology 13:469-477

Garg VK, Sinha S, Sarkar R (2008). “Glycolic Acid Peels Versus Salicylic-Mandelic Acid Peels in Active Acne Vulgaris and Post-Acne Scarring and Hyperpigmentation: A Comparative Study.” Dermatol Surg 35:59-65.

Kornhauser A, Coelho SG, Hearing VJ (2012). “Effects of Cosmetic Formulations Containing Hydroxy acids on Sun-Exposed Skin: Current Applications and Future Developments.” Dermatology Research and Practice. Doi: 10.1155/2012/710893.

Narda M, Trullas C, Brown A, Piquero-Casals J, Granger C, Fabbrocini G.(2021) “Glycolic acid adjusted to pH 4 stimulates collagen production and epidermal renewal without affecting levels of proinflammatory TNF-alpha in human skin explants.” Journal of Cosmetic Dermatology 20:513-521.

Okano Y, Abe Y, Masaki H, Santhanam U, Ichihashi M, Funasaka Y. “Biological effects of glycolic acid on dermal matrix metabolism mediated by dermal fibroblasts and epidermal keratinocytes.” Exp Dermatol. 2003; 12 Suppl 2: 57–63.

Sharad J (2013). “Glycolic acid peel therapy – a current review.” Clinical, Cosmetic and Investigational Dermatology 6:281-288.

DeDormael R, Bastien P, Sextus P, Gueniche A, Ye D, Tran C, Chevalier V, Gomes C, Souverain L, Tricaud C (2019). “Vitamin C Prevents Ultraviolet-induced Pigmentation in Healthy Volunteers: Bayesian Meta-analysis Results from 31 Randomized Controlled versus Vehicle Clinical Studies.” J Clin Aesthet Dermatol. 12(2): E53-E59How does retinal help with dark spots and even out skin tone?

Leydon J, Stein-Gold L, Weiss J (2017). “Why topical retinoids are mainstay of therapy for acne.” Dermatol Ther (Heidelb) 7: 293-304.

Kornhauser A, Coelho SG, Hearing VJ (2012). “Effects of Cosmetic Formulations Containing Hydroxy acids on Sun-Exposed Skin: Current Applications and Future Developments.” Dermatology Research and Practice. Doi: 10.1155/2012/710893.
Mukherjee S, Date A, Patravale V, Korting HC, Roeder A, Weindl G (2006). “Retinoids in the treatment of skin aging: an overview of clinical efficacy and safety.” Clinical Interventions in Aging. 1(4) 327-348.

Zasada M and Budzisz E (2019). “Retinoids: active molecules influencing skin structure formation in cosmetic and dermatological treatments.” Adv Dermatol Allergol XXXVI(4): 392-397.

Pinnell SR, Yang H, Omar M, Monteiro Riviere N, De Buys HV, Walker LC, Yang Y, Levine M (2001). “Topical L-Ascorbic Acid: Percutaneous Absorption Studies.” Dermatol Surg 27:137-142.