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Phyto Complexes

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As the quest for natural ingredients is growing, the interest in phyto-cosmetics is raising. Phyto in Greek means plant and phyto-cosmetics are products based on natural plant extracts or containing predominantly ingredients derived from plants such as polyphenols, vitamins, etc. Since I started working on ingredients development 15 years ago, I focused my attention on natural extract, especially those rich in active molecules, preferably from the same chemical family (1, 2). My grandfather introduced phyto-cosmetics in Italy in the early 30s and I read some of his early publications. In particular, I was intrigued by how he described the power of ingredients families or phyto-complexes when compared to single ingredients from the same family. In the late 50s he published together with my uncle, at the time a young chemist in Milano, a paper on beta carotene where he highlighted the capacity of carotenoids as a family to have a more powerful effect than single moleculebeta carotene on a series of skin benefit (beta carotene was used at the same concentration of the phyto-complex).

We know that plants are often mobilizing different isoforms, variants of same molecule to create a more effective and sophisticated response to a particular need. Molecule families are common, they often work in synergies and there are evidences that molecules belonging to the same family can protect each other against oxidation, so increasing stability of the phyto-complex. Phyto-complex is not a new definition neither a new concept, but I think the recent understanding of the importance of a multifactorial and synergetic approach when formulating a product for cosmetic applications has brought a renovated interest into this strategy and into phyto-complexes.

While in the last 50 years the approach to treatment was a reductionist approach based on single purified molecules (often compared to a plant extract with little efficacy), more recently a comprehensive approach based on plant extract fractionation and enrichment has proven to be as effective as single molecules, and often more stable in finished formulations. Phyto-complexes are also the basis of modern aromatherapy, where complex composition of essential oils showed therapeutic values to treat conditions associated to diseases (3). Moreover, studies have shown that encapsulation of polyphenols phyto-complexes were able to increase wound healing (4). Interestingly, when single molecules where combined with their phyto-complex, the complex acted as an enhancer to increase molecule bioavailability, and helping stabilizing the molecule itself (5). Numerous experiments have shown the phyto-complex superior to the single molecule in mechanisms meant to reduce inflammation, such autophagy (4) and apoptosis (5). Carotenoid such as lycopene was significant inferior in anti-oxidant activity when compared to tomato seed phyto-complex (6, 7).

Finally and intriguing, combination of phyto-complexes from different parts of the same plant was superior to single plant part extracts when used for healing (8). In conclusion, evidences exist to support the use of phyto-complexes instead of (or in combination) with single molecules from the same family. The use of phyto-cosmetics and phyto-complexes will grow in the next years as more experimental evidences on their stability and efficacy will be established.


Tomato Seed Oil (TSO) is superior to Purified Lycopene (Lyc) in inhibiting ROS production (Ref 8)



  1. Ebrahimi SN, Gafner F, Dell’Acqua G, Schweikert K, Hamburger M. Flavone 8-C-glycosides from Haberlea rhodopensisFriv. (Gesneriaceae). Helvetica Chimica Acta, 94 (1): 38–45, 2011.
  2. Germani F, Dell’Acqua G. An extract from blueberry processing by-product (press cake) inhibits blue light induced physiological changes and increases radiance in human skin, Poster IFSCC Milano, 2019
  3. Scuteri D, Morrone LA, Rombolà L, Avato PR, Bilia AR, Corasaniti MT, Sakurada S, Sakurada T, Bagetta G. Aromatherapy and Aromatic Plants for the Treatment of Behavioural and Psychological Symptoms of Dementia in Patients with Alzheimer’s Disease: Clinical Evidence and Possible Mechanisms. Evid Based Complement Alternat Med 2017:9416305, 2017
  4. Moulaoui K, Caddeo C, Manca ML, Castangia I, Valenti D, Escribano E, Atmani D, Fadda AM, Manconi M. Identification and nanoentrapment of polyphenolic phytocomplex from Fraxinus angustifolia: in vitro and in vivo wound healing potential. Eur J Med Chem 89:179-88, 2015
  5. Hasa D, Perissutti B, Dall’Acqua S, Chierotti MR, Gobetto R, Grabnar I, Cepek C, Voinovich D. Rationale of using Vinca minor Linne dry extract phytocomplex as a vincamine’s oral bioavailability enhancer. Eur J Pharm Biopharm. 84(1):138-44, 2013
  6. Lascala A, Martino C, Parafati M, Salerno R, Oliverio M, Pellegrino D, Mollace V, Janda E. Analysis of proautophagic activities of Citrus flavonoids in liver cells reveals the superiority of a natural polyphenol mixture over pure flavones. J Nutr Biochem 58:119-130, 2018
  7. Ettorre A, Frosali S, Andreassi M, Di Stefano A. Lycopene phytocomplex, but not pure lycopene, is able to trigger apoptosis and improve the efficacy of photodynamic therapy in HL60 human leukemia cells. Exp Biol Med (Maywood) 235(9):1114-25, 2010
  8. Müller L, Catalano A, Simone R, Cittadini A, Fröhlich K, Böhm V, Palozza P. Antioxidant capacity of tomato seed oil in solution and its redox properties in cultured macrophages. J Agric Food Chem 61(2):346-54, 2013
  9. van Vuuren SF, Viljoen AM. In vitro evidence of phyto-synergy for plant part combinations of Croton gratissimus (Euphorbiaceae) used in African traditional healing. J Ethnopharmacol 119(3):700-4, 2008


About the Author

Giorgio Dell’Acqua, PhD, is a cosmetic scientist and a consultant for the personal care industry. A graduate from the University of Rome, Italy, he worked for 15 years as an investigator in applied medical research in Universities such as Mount Sinai Medical School in New York and Harvard Medical School in Boston. Moving to the private sector in 2000, he has spent the last 19 years as an executive and cosmetic scientist in the personal care industry. He is specialized in skin and hair care ingredients, finished product development and technical marketing. He has helped bring more than 200 successful active ingredients and finished products to market and has authored more than 60 publications in medicine and cosmetic science. From last 10 years he has been writing and lecturing on natural cosmetic ingredients, sustainable supply chain, and helped sourcing, developing and bringing to market many natural ingredients. Some of his recent product development activity has focused on food by products to cosmetics, prebiotics and postbiotics to skin, and adaptogens for skin and hair care. He is an award winning speaker on natural ingredients and a regular columnist on sustainability and cosmetic science. He is also the chair of the Scientific Committee for the New York Society of Cosmetic Chemists and its scientific blogger.

Sunscreen Monograph Proposed New Rules and its Impact on Formulations

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In February of 2019, the FDA stunned the cosmetics industry one more time by publishing proposed rules for sunscreens in the Federal Register.  As indicated by its name, these are only proposed rules but historically companies have implemented proposed rules into their formulations to be proactive.  The FDA used the argument that since the issuance of the original Final Monograph in 1999, the use of sunscreens and exposure to UV filters substantially increased.  It was important for the Agency to re-evaluate sunscreens based on current scientific understanding and extend safety assessments for such topical products to include chronic use.


What are the changes

The biggest change that the proposed ruling brought was the reduction of the number of Category I (Safe and effective) approved sunscreens that can be used in the US.  The FDA reduced the number of sunscreens in Category I from 16 to 2.  These two sunscreens are Titanium Dioxide and Zinc Oxide and they are approved at a level of 25% in formulations.  In addition, the FDA classified paminobenzoic acid (PABA) and Trolamine Salicylate as Category two II (Not safe and effective) which means that these two sunscreens can no longer be used in sunscreen formulations.  The remaining 12 sunscreens namely, Cinoxate, Dioxybenzone, Ensulizole, Homosalate, Meradimate, Octinoxate, Octisalate, Octocrylene, Padimate O., Sulisobenzone, Oxybenzone, and Avobenzone were classified as Category III (Additional data needed to confirm safety and efficacy).  These 12 sunscreens can be used in formulations until the FDA categorizes them into Category I or II.  From a formulation prospective, the FDA decreased the number of sunscreens to 14 until further action.  The FDA did not address the percentage at which those sunscreens can be used specifically, but probably a good fall back would be to use them at the levels published in the 1999 Monograph.  The proposed rule does not address the sunscreen active ingredients that are being evaluated under a TEA (Time and Extent Application).

In addition, the FDA proposed changes to the types of dosage forms that can be used for sunscreen products.  For Category I, they proposed the following dosage forms: oils, lotions, creams, gels, butters, pastes, ointments and sticks.  The FDA proposed Category I status for sprays subject to testing for inhalation and flammability.  Powders were classified as Category III pending additional data.  All additional dosage forms including wipes, shampoos, body washes, towelettes and others are considered as new drugs.

Broad spectrum testing was also changed.  In most parts of the world, the Critical Wavelength is used to measure broad spectrum.  The FDA is proposing to use the UVAI/UV ratio of 0.7 or higher as a standard for all sunscreens of SPF 15 or higher.  The FDA had previously proposed to make the ratio 0.9 or higher but realized that it is impossible to achieve such ratio with the portfolio of approved Category I sunscreens available in the US.  The new ratio seems reasonable but now manufacturers must perform two tests for global products, the UVAI/UV ratio and the Critical Wavelength.

Final formulation testing and labeling requirements have changed as well.  The FDA proposed to label products with the lowest SPF number achieved in in vivo testing to eliminate the variability associated with such testing.  The FDA also raised the maximum labeled sunscreen product to SPF 60+ and they attributed their decision to the lack of evidence that higher SPF product could bring meaningful clinical benefits.  The FDA proposed to label sunscreens products with an SPF 30 or higher in increments of 10 (i.e. SPF 30, 40, 50 and 60+).  They also proposed labeling sunscreens with SPF 15 to 29 to be in increments of 5 (i.e. SPF 15, 20, and 25).  The FDA also brought attention to products that are labeled SPF2 to SPF 14 and proposed that such products be removed from the market since they do not bring any adequate protection to consumers.

Sunscreens-insect repellant combination products are proposed to be classified as Category II due to incompatibility between FDA and EPA labeling instructions.  In addition, the FDA believes that combining DEET with certain sunscreens may increase cutaneous absorption of either or both.


What is the impact

In this proposed ruling, the FDA addressed so many safety concerns that companies and consumers suspected for years.  Many sunscreens used in the US are no longer used in Europe, Asia and the rest of the world due to their safety profiles.  However, these markets have alternative sunscreens in their portfolio that they can use to formulate safe and effective sunscreens.  In the US, such large portfolio of approved Category I sunscreen does not exist, so I would like to urge the FDA to speed the approval of all the molecules awaiting approval in the TEA process.  This will enable US formulators to have the same tools that their counterparts in the rest of the world have.  In the meantime, I am sure that formulators will use their creativity and start adapting their new formulations to the guidelines set forth by the FDA.


About the Author

Dr. Hani Fares started his career in personal care studying the effect of solvents on sunscreen chemicals.  His interest in skin drug delivery especially from polymeric matrices grew during his graduate work at Rutgers, where he completed his Ph. D. in Pharmaceutics.

Dr. Fares worked at Block Drug and GlaxoSmithKline where he held positions in research and development in the areas of skincare and oral care.  After that, he joined L’Oreal where he held several positions of increasing responsibility leading to AVP of skincare.  He is currently the Senior Director of skincare and oral care at Ashland Specialty Ingredients.  Dr. Fares is the author of many publications, and patents and made many presentations in national and international meetings in the areas of suncare, skincare, and oral care.


Development of Color Products – From William Perkin to Urban Decay

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Russian Red. 999. Ruby Woo. Pioneer. Androgyny. No. 1.


What do these words call to mind?

Beauty product enthusiasts the world over will recognize these iconic shade names currently inhabiting their purse. (The author tips her hat to the product developers and marketers at Dior, MAC, L’Oreal, Chanel, and Jeffree Star.)

At the risk of taking the technology for granted, what went into creating the iconic colors?

Accidental experiments, bold defiance, an enterprising mind, good taste, shrewd manufacturing, and hours of color matching in the product development laboratories.

A Short History Lesson: Accidental Chemistry Makes Mauve

In 1856 over Easter vacation, 18-year-old William Perkin set out to isolate quinine from coal tar. Perkin was student of great German organic chemist August Wilhelm von Hofmann at London’s Royal College of Chemistry. Quinine is a valuable compound with valued anti-malarial properties. However, any chemist who knows its chemical structure would not have attempted this approach. During Perkin’s time however, the structure of benzene was not even understood.

Chemical structure of quinine and benzene

Embarking on what some might call a fool’s errand, Perkin attempted to chemically isolate the compound. With an artist’s eye, he stumbled upon mauve instead, or “aniline purple”, through a series of serendipitous experiments.

Mere luck would not have been enough to produce entire libraries of color additives manufactured today. Against his professor’s recommendation –(proof that we should always make final judgement calls for ourselves rather than obey advice without discernment)– Perkin commercialized his discovery. With the financial support of his father, a construction contractor, he developed the processes for the production and use of the new aniline purple dye. In 1857, Perkin opened his factory at Greenford Green near London. From modest beginnings, the synthetic dye industry and its relative, the pharmaceutical industry, was born.

Despite falling short of his original goal (R&D scientists and research leaders: take note!), Perkin discovered the world’s first synthetic dye, opening up an entire chemical industry and painting the mass markets with bedazzling color.

Each time we swivel up a beloved tube of lipstick for application, we pay homage to Perkin. Our ability to make style statements with color products was enabled entirely by Perkin’s accidental discovery in 1856, shrewd manufacturing, and business development.


Color Additives for the Consumer Packaged Goods Industry

Perhaps the most tightly regulated in the cosmetic industry, these ingredients play an important role in making products visually appealing for consumers. With the right product, it empowers the consumer to make artistic statements of her choice through color products, unencumbered.

Modern day color additives have come a long way since 1856, and safely used for more than 150 years. Color additives are used to liven up a product. As industrial research brought science into industry, the industrial colorist was a profession that developed alongside industrial design after World War I. American designers and artists worked together on the design of tasteful and attractive goods to promote culture and civility to a nation that had become overwhelmed with unsophisticated immigrants from largely rural regions of southern and eastern Europe.

For manufacturers, the mass production of different colored goods posed other challenges. The need to predict which colored products would be attractive to the masses required market research, upkeep with Parisian fashion trends, and an understanding of consumer psychology. After World War II, the epicenter of mass market fashion moved to New York, where consumers exercised -and still very much do today- the power of choice over color for self-expression.

In broader contexts in business, color is used to liven a brand or company through its logo, to create instantaneous product recognition, set the visual tone and impression, or even influence consumer psychology. As such, judicious choice and use of color in products, advertisements, and on live consumer lips and faces, can pose as effective marketing campaign strategy to increase a company’s awareness and presence in the marketplace.


Judicious use of color even in a company logo can make a difference to a company’s brand, by igniting consumer emotion. Image source: https://www.fastcompany.com/3028378/what-your-logos-color-says-about-your-company-infographic


Technology Advancements Empowers the Consumer as Artist

Since the advent of brands like Urban Decay from the 1990s, bold colors have emerged on the cosmetic market, like a relentless catwalk and lightshow of color. Greens, blues, the blackest black, pinkest pink, and everything unicorn, iridescent, pearlescent, glow-in-the-dark, and in-between have become mainstays of any cosmetic product line aiming to market itself as exciting and cutting-edge.


Image source: www.urbandecay.com

Owing to technological advancements, consumers no longer have to choose between long-lastingness, comfort, payoff, or value. Oftentimes, a large palette of color options accost her, with the option of layering more than one color over her lips, eyelids, lashes, or face, to achieve her desired shade and look.


Less is More?

Presented with the sleuth of options, studies on the paradox of choice by Professors Barry Schwartz and Sheena Iyengar come to mind. While more isn’t always better, in the world of cosmetic products and beauty trends today, more DOES mean more. The wide array of color options delights the beauty consumer.

Today, this consumer is as complex in skin tone, gender, political association, and values, and expects her beauty products to reflect her multidimensional nuanced identity just as effectively. Variety in color and shade options (particularly in skin-matching tones for foundations) have been in long-time demand. Consumers asked, and beauty companies have listened.

The market today has made progress since the era of limited shade range housed in drugstore-branded compacts, where nary a tester was in sight for the consumer to choose a shade that matched her skin tone. “Nude” can mean many different shades. Brands such as Beauty Bakerie were founded upon this very premise of inclusion, turning shade names upon its head. Where brands used to start shade naming from light to dark, Beauty Bakerie makes it a point to call its darkest shade, “1”.


Jackie Aina, influencer known for pushing companies towards shade diversity and racial inclusivity. She demonstrates Too Faced’s pigmented emulsion foundation product in a range of new shades. Image source: https://www.glamour.com/story/jackie-aina-too-faced


Advent of Color via the Chemical Industry, Social Media, and Business

The evolution of consumer tastes tracks the ubiquitous use of social media and the rise of the beauty blogger voice,, both of which continue to drive demand volumes and trends today. Continued delivery of chemical and formulation innovation is what enables the fashionistas’ envelope-pushing on what is considered wearable and trendy. Contrapuntal to the international beauty companies’ main-stream product development approach, the rise of indie brands and the use of direct selling (e.g. Glossier) have sprung up to fill market whitespaces from the supply side. From the formulator’s standpoint, innovation has liberated what is possible in performance and payoff to meet the ever-growing consumer demands for “new”. Consumer force and industry innovation, very much lubricated by social media, has progressed hand in hand dramatically in the last decade.

The consumer voice has gained a significant amount of power in the beauty and consumer products industry today. The onslaught of small beauty brands has forced larger beauty conglomerates to innovate, push daring and imaginative color products, or buy up these small brands in an effort to be more competitive.

Development of technology by material suppliers continues to facilitate the creative explosion of color products. Raw ingredient suppliers in Europe, Asia, and the Americas push the boundaries of surface functionalization, particle, colloidal, material and formulation development, designing polymers and optimizing production capabilities to enable supply and production of novel raw ingredients. The advancement of technology and manufacture production has put high-performing value products directly into the consumers’ hands, democratizing beauty and lowering the cost of self-expression.

With the glut of products and trends, it remains to be seen where the push-pull conversation between consumer and company will take us. It is an exciting time to observe how raw ingredient suppliers and product development companies big and small will respond to market forces.



[1] https://www.sciencehistory.org/historical-profile/william-henry-perkin

[2] Rydzewski, R. M., Real World Drug Discovery

[3] https://www.sciencehistory.org/distillations/magazine/colors-run-riot

[4] https://medium.com/marketing-and-entrepreneurship/the-psychology-of-logo-color-in-how-consumers-view-your-brand-d3afe84f2bdb

[5] https://www.fastcompany.com/3028378/what-your-logos-color-says-about-your-company-infographic

[6] https://hbr.org/2006/06/more-isnt-always-better

[7] https://www.glamour.com/story/jackie-aina-too-faced

[8] https://www.wsj.com/articles/celebrities-like-kylie-jenner-are-upending-the-52-billion-beauty-industry-1543401001

[9] https://blogs.wsj.com/cmo/2015/06/09/bethany-mota-overtakes-michelle-phan-as-youtubes-top-beauty-producer/

[10]  https://www.huffingtonpost.co.uk/sophie-bianchi/beauty-bloggers-zoella_b_11566248.html

[11] https://www.wsj.com/articles/small-cosmetics-brands-make-over-the-beauty-market-by-targeting-millennials-11556296365

[12] https://www.wsj.com/articles/glossier-tops-billion-dollar-valuation-with-latest-funding-11552993200


About the Author

A polymer chemist in the personal care industry, Dr. Diane Lye is a product developer and formulator, translating novel raw materials into stable color, SPF, and skin care actives-containing consumer products. She studies the physicochemical properties of raw ingredients and finished formulas to map the consumer experience onto quantifiable entities.

Dr. Lye cut her fundamental scientific teeth by working on the design, synthesis, and bulk property characterization of main-chain block copolymer materials with supramolecular self-recognition end groups with the Weck Lab at the NYU Molecular Design Institute. She has 10 academic publications in her time in academic institutions, and developed a market commercialization assessment and plan for a dermal technology in conjunction with NYU Stern and NYU Langone.

Basis for and Clinical Importance of Stratum Corneum Acidification

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While long suspected to be an important regulator of cutaneous antimicrobial defense, the ‘acid mantle’ of the stratum corneum is also a critical regulator of three additional, critical functions – permeability barrier homeostasis, integrity/cohesion (desquamation), and restriction of pro-inflammatory cytokine signaling (i.e., dampening of inflammation) (1,2). The pH of normal human stratum corneum ranges from 4.5-5.5, with the lowest levels occurring in darkly-pigmented individuals (3).


The epidermis renewal time is about 28 days, during which a pH gradient is formed. For several decades, it was assumed that the low pH of the stratum corneum resulted from the deposition of sebaceous gland-derived free fatty acids (FFA) on the skin surface. But it is now evident that secreted sebaceous gland products are not required for stratum corneum acidification, and may have limited impact on pH, as it has been observed that sebaceous gland-impoverished skin sites are as acidic as adjacent, sebaceous gland-enriched sites (4). Instead, pH acidification is achieved by several endogenous pathways including by-products of keratinization (filaggrin processing accounting for 0.5 unit of the bulk pH of the stratum corneum) (5), synthesis of FFA from phospholipids by the secretory phospholipase A2 (contributing to »one unit of SC bulk pH) (6,7), and the sodium-proton exchanger NHE1. In addition, the contribution of melanosome transfer in reducing skin pH, further increases skin acidic mantle in dark pigmented skin compared to light pigmented skin (3).


Skin surface pH is an essential component for a functional skin barrier. It provides antimicrobial defense, and regulates stratum corneum desquamation (8). Indeed, the upper layers of the epidermis carry several enzymes which activity is pH-dependent such as lipid generating enzymes, working best at acidic pH, that supply the lipid envelope of the stratum corneum (ceramides and phospholipids), or extracellular serine proteases, which are responsible for corneocytes shedding, that work best at neutral to alkaline pH (9). In addition, these proteases also play a role in skin inflammation, as they can process and activate inflammatory precursors such as IL-1α and IL-1β (10,11).


The importance of skin pH has also been highlighted in pathologies like ichthyosis vulgaris or atopic dermatitis, which depict dramatic barrier function impairment. In both diseases, the stratum corneum pH is increased by approximately 0.5 unit compared to healthy skin.  This increase has been correlated with: 1. mutations in the Filaggrin protein, impairing its degradation in smaller components associated with pH reduction) and, 2. excessive serine protease activity, leading to excessive desquamation, cytokine cascade and inflammation) (5,11,12).


Age also seems to play a role in stratum corneum pH. Aged human stratum corneum (50-60 years old) displays a higher pH than in a younger skin, with proven adverse consequences for both barrier function and stratum corneum cohesion. This age difference has been linked to decreased expression/activity of the sodium-proton exchanger NHE1 and the secretory phospholipase A2 in aged individuals (13).


In all cases, providing exogenous acidification has shown clinical benefits. Several rat and mouse models mimicking atopic dermatitis, fragile neonatal skin or an aged phenotype have been employed to demonstrate that defects in the barrier function maturity and stratum corneum cohesion can be corrected through restoring a normal skin pH (13–15). Moreover, in the case of atopic dermatitis, exogenous stratum corneum acidification has also been reported as beneficial in further preventing the ‘atopic March’ associated with aeroallergen-induced asthma (16).


In conclusion, the importance and clinical benefits of maintaining a low skin surface pH are becoming increasingly evident, especially in inflammatory dermatoses such as atopic dermatitis as well as aged skin, where the use of reduced pH emollients and cleansers should be strongly recommended to maintain a skin barrier in good condition.



  1. Chuong CM, Nickoloff BJ, Elias PM, Goldsmith LA, Macher E, Maderson PA, et al. What is the « true » function of skin? Exp Dermatol. 11(2):159‑87, 2002
  2. Elias PM. Stratum corneum acidification: how and why? Exp Dermatol 24(3):179‑80, 2015
  3. Gunathilake R, Schurer NY, Shoo BA, Celli A, Hachem J-P, Crumrine D, et al. pH-regulated mechanisms account for pigment-type differences in epidermal barrier function. J Invest Dermatol 129(7):1719‑29, 2009
  4. Man MQ, Xin SJ, Song SP, Cho SY, Zhang XJ, Tu CX, et al. Variation of skin surface pH, sebum content and stratum corneum hydration with age and gender in a large Chinese population. Skin Pharmacol Physiol 22(4):190‑9, 2009
  5. Gruber R, Elias PM, Crumrine D, Lin T-K, Brandner JM, Hachem J-P, et al. Filaggrin genotype in ichthyosis vulgaris predicts abnormalities in epidermal structure and function. Am J Pathol 178(5):2252‑63, 2011
  6. Mao-Qiang M, Feingold KR, Jain M, Elias PM. Extracellular processing of phospholipids is required for permeability barrier homeostasis. J Lipid Res 36(9):1925‑35, 1995
  7. Ilic D, Bollinger JM, Gelb M, Mauro TM. sPLA2 and the epidermal barrier. Biochim Biophys Acta 1841(3):416‑21, 2014
  8. Elias PM. Structure and function of the stratum corneum extracellular matrix. J Invest Dermatol 132(9):2131‑3, 2012
  9. Hachem J-P, Roelandt T, Schürer N, Pu X, Fluhr J, Giddelo C, et al. Acute acidification of stratum corneum membrane domains using polyhydroxyl acids improves lipid processing and inhibits degradation of corneodesmosomes. J Invest Dermatol 130(2):500‑10, 2010
  10. Hansson L, Bäckman A, Ny A, Edlund M, Ekholm E, Ekstrand Hammarström B, et al. Epidermal overexpression of stratum corneum chymotryptic enzyme in mice: a model for chronic itchy dermatitis. J Invest Dermatol 118(3):444‑9, 2002
  11. Cork MJ, Robinson DA, Vasilopoulos Y, Ferguson A, Moustafa M, MacGowan A, et al. New perspectives on epidermal barrier dysfunction in atopic dermatitis: gene-environment interactions. J Allergy Clin Immunol 118(1):3‑21; quiz 22‑3, 2006
  12. Hatano Y, Man M-Q, Uchida Y, Crumrine D, Scharschmidt TC, Kim EG, et al. Maintenance of an acidic stratum corneum prevents emergence of murine atopic dermatitis. J Invest Dermatol 129(7):1824‑35, 2009
  13. Choi E-H, Man M-Q, Xu P, Xin S, Liu Z, Crumrine DA, et al. Stratum corneum acidification is impaired in moderately aged human and murine skin. J Invest Dermatol 127(12):2847‑56, 2007
  14. Fluhr JW, Man M-Q, Hachem J-P, Crumrine D, Mauro TM, Elias PM, et al. Topical peroxisome proliferator activated receptor activators accelerate postnatal stratum corneum acidification. J Invest Dermatol 129(2):365‑74, 2009
  15. Fluhr JW, Crumrine D, Mao-Qiang M, Moskowitz DG, Elias PM, Feingold KR. Topical liver x receptor activators accelerate postnatal acidification of stratum corneum and improve function in the neonate. J Invest Dermatol 125(6):1206‑14, 2005
  16. Lee H-J, Lee NR, Kim B-K, Jung M, Kim DH, Moniaga CS, et al. Acidification of stratum corneum prevents the progression from atopic dermatitis to respiratory allergy. Exp Dermatol 26(1):66‑72, 2017


About the Authors

Carine Mainzer, PhD – Scientific Support Manager, Silab

Before joining Silab in 2016, Dr Mainzer was a postdoctoral scholar in the Department of Dermatology at University of California San Francisco under the supervision of Dr. Peter Elias and Dr. Yoshikazu Uchida, where her work focused on the communication between inflammatory cells and cutaneous cells under bacterial challenges. She obtained her Ph.D. from the University of Lyon (France) in 2014 with work focused on the involvement of the Insulin-like growth factor (IGF)-1 on epidermal differentiation and aging. Dr. Carine Mainzer has been within the cosmetic industry since several years now, working notably with Johnson & Johnson Consumer France, Natura and Silab. Her current position offers her the opportunity to continue applying her scientific expertise to the research problematics of the cosmetic industry in various domain around skin.


Peter M Elias, MD. – Dermatology Service, Department of Veterans Affairs Medical Center and Department of Dermatology, University of California

Dr. Elias, Staff Physician, San Francisco VA Medical Center and Professor Emeritus, University of California San Francisco, is in part responsible for the present wealth of knowledge on the structure and myriad functions of mammalian stratum corneum.  His pioneering research since the 1970’s has dispelled the myth of the stratum corneum as a “dead, keratinized, basket-weave” structure, to establish the iconic “brick and mortar” model.  The stratum corneum is now viewed as a metabolically active, two-compartment composite that functions as a biosensor. The resultant “outside-in” concept of the barrier as a prime mover in the pathogenesis of cutaneous disease has also been a highlight of his work, with the paramount role of skin barrier dysfunction in disease pathogenesis now widely recognized. Over the past 40 years, his lab has been the destination for over 100 young investigators from around the world, a trend that continues to enrich the field of academic dermatology with an armamentarium of techniques and disciplines on epidermal structure and function.  Dr. Elias mentors his vast network of associates and postdoctoral fellows, past and present, several of whom have achieved leadership roles in academia and industry the world over.  His oeuvre comprises over 650 scientific publications, including several books that he has either edited or co-edited.