Skin penetration of Ascorbic Acid

Today I wanted to look at a research paper primarily led by Dr. Sheldon R. Pinnell. He is one of the founders of Skinceuticals and contributed much of the early research on the use of Vitamin C as ascorbic acid on skin. He and his group also discovered the synergistic effect of Vitamin C, Vitamin E, and Ferulic acid – which is commonly used in many products on the market today.

The data from this paper is often quoted in marketing material for Vitamin C serums, but one extremely important piece of information is often left out – the data was collected from pigs, white Yorkshire pigs to be exact.

Many people also have ethical concerns when it comes to the use of animals in cosmetic research. Synthetic and lab grown human skin equivalents are being researched and tested which will one day replace the use of animal as well as human testing in cosmetics.

It should be clear that human skin and pig skin are not the same, but they do have similar properties which is why it is often used in experiments. However, one should never assume that data from a pig can be assumed to be the same for a human. The movement and deposition of chemicals often differs between human and pig skin.

From my searches, I haven’t been able to find similar research performed on humans. This paper in particular has led to some of the often quoted “rules” about ascorbic acid.

“Ascorbic acid must have a pH below 3.5 for effective penetration.”

Pinnell and his group tested a 15% ascorbic acid solution adjusted to different pHs ranging from 2 to 5. The 15% ascorbic acid solutions also contained 2% zinc sulfate, 0.5% bioflavonoids, 1% hyaluronic acid, and 0.1% citrate.

While the control situation wasn’t described it’s likely either the vehicle (product without the ascorbic acid) or a water solution was applied to the skin. The control measurement shows that there is some inherent levels of ascorbic acid already present in the skin from the diet.

The test solutions were applied to the pig skin using a Hill Top Chamber. A Hill Top Chamber is a small and round disk which is placed on the surface of the skin, the product is placed in the chamber or a piece of fabric is soaked in the testing material, and the entire chamber is then sealed. This prevents loss of product from evaporation and is a common method of performing occlusive test patches.

The ascorbic acid solutions at pH 2.5, 3.0, 3.5, 4.0, and 5.0 were performed on three pigs, however the control, pH 2, and 4.5 were only performed on two pigs.

The Hill Top Chamber was soaked with 0.2 mL of the ascorbic acid solution then sealed for 24 hours. After this period of occlusion, the skin washed then stripped of the stratum corneum and then small pieces of the skin was removed and tested for ascorbic acid content.

As you can see from the data, the amount of ascorbic acid found in the skin was much higher in ascorbic acid solutions at pH 3.5, 3.0, 2.5, and 2.0. The researchers theorize that it is due to the pKa of ascorbic acid which is 4.2. When the pH of a solution containing ascorbic acid is lower than its pKa more of the ascorbic acid will be protonated. Protonated ascorbic acid is neutrally charged which may allow it to enter the skin more easily.

It’s important to notice the error bars on the amount of ascorbic acid absorbed at pH 2.0. There is considerable deviation from the mean in the results even though it was only tested on 2 subjects. More test subjects would provide a clearer idea of how much ascorbic acid would penetrate at pH 2 on an average population of pigs.

Statistical differences also weren’t calculated between the data points, for example it’s difficult to tell from the way that the data is presented if there is a change in ascorbic acid content between the control, pH 4.0, 4.5, and 5.0 – even if they look different on the graph. Likewise, it’s difficult to tell if there is an increase in ascorbic acid penetration between pH 3.0 and pH 2.5 – despite the trend with pH 2.0 pushing you towards that inference. It’s likely that there is a statistically significant difference between absorption between pH 3.5 and 3.0, but a larger study would provide us  with more confident answers.

So based on this data, many further studies and brands have assumed that a pH below 3.5 results in considerable more skin penetration of ascorbic acid on humans – despite these results being performed on pigs, and relative low strength of the study. If the reason why ascorbic acid is more easily absorbed into the skin is due to the pKa then this would likely hold true for humans as well.

This assumption is often presented as fact, which is misleading. It also doesn’t take into account other factors present in a cosmetic product, such as penetration enhancers. Encapsulation, surfactants, and solvents could increase (or decrease) the amount of ascorbic acid absorbed into the skin regardless of the product’s pH.

In this experiment, the stratum corneum was removed before measurements of ascorbic acid to test for deep penetration of ascorbic acid. It’s possible that some of the benefits conferred by topical application of ascorbic acid aren’t facilitated by deep penetration, the antioxidant and photoprotective effect of ascorbic acid may still occur when it is present in or on the stratum corneum. Other benefits like reduction of hyperpigmentation and an increase in collagen production are likely dependent on penetration past the stratum corneum.

Unfortunately I haven’t been able to find further studies on humans or otherwise to provide answers to these questions.

“Ascorbic acid serums must be at least 10% to be effective”

After the first experiment of testing 15% ascorbic acid with different pHs, Pinnell and his group tested how concentration of ascorbic acid affects skin penetration. This time they tested 7 ascorbic acid solutions with varying concentrations all at pH 3.2. The concentrations of the rest of the formulation are assumed to be the same as the previous experiment.

The ascorbic acid solutions were applied in the same manner, with a Hill Top Chamber for 24 hours, followed by washing, stripping, and then assessment.

The maximum amount of ascorbic acid penetration was seen when 20% ascorbic acid at pH 3.2 was used.

All concentrations were tested on 3 pigs, and there is quite a bit of deviation from mean between absorption among the 3 pigs tested. This makes it difficult to assess the true difference in absorption between a 10% and 15% ascorbic acid, and a 15% and 20% ascorbic acid.

Absorption also seemed to peak at 20%, the 25% ascorbic acid solution penetrated less than the 20%, and the 30% even less so. The researchers did not explore or hypothesize on why this occured, and I’ve been unable to find an answer in any later research as well.

While 20% ascorbic acid certainly led to the greatest increase in levels of ascorbic acid, the 5% solution still increased ascorbic acid levels in the pig skin by about 6 fold.

It’s very important to remember that the way that this experiment was performed does not mimic the way that ascorbic acid solutions are often applied to the skin. With the Hill Top Chamber, the solvent (in this case water) is not allowed to evaporate – whereas when we apply it to the skin the solvent evaporates. What this means is that the kinetics of ascorbic acid penetration into the skin may not be the same.

For example, if half of the solvent of a 10% ascorbic acid solution evaporates, it is equivalent to a 20% ascorbic acid solution – the total amount of ascorbic acid by mass is the same, but the concentration has changed. This may mean that we could see a different maximum absorption by concentration in an experiment where the solvent was allowed to evaporate the way that it is often applied.

Human clinical trials with “low” ascorbic acid concentrations, 3% ascorbic acid cream and a 5% ascorbic acid cream, were able to show statistically significant improvements on measurements of photodamage and photoageing in their study groups.

Another thing many people hold on to is the concept that their products must be working at “maximum efficiency”, unfortunately this is unrealistic and there’s going to be variations in the amount of ascorbic acid that penetrates your skin with each application – even the amount that you apply to your skin will vary each time. This is why good cosmetic studies are performed over a longer period of time.

For example, if we look at the 20% concentration, the pig skin concentration of ascorbic acid increased to about 1100 pmol of ascorbic acid per mg of pig skin, which is about 0.19 μg ascorbic acid per mg of pig skin. 1.0 mg of a 20% ascorbic acid (w/w) contains about 1135589.37 pmol of ascorbic acid, if that helps give you a sense of the “efficiency”. In these experiments, 200 μL or 0.2 mL solution was used in total for each application, which contains about 227117874.1767 pmol of ascorbic acid if we assume density of the solution (w/w) is 1.

Higher concentrations of ascorbic acid may lead to more irritation (measured by skin redness or erythema), but I haven’t found any studies that looked at this specifically.

I’m going to end this post here, to be continued next week, where we’ll look at the data behind Vitamin C’s “reservoir” effect.

Source: Pinnell, S. R., Yang, H. , Omar, M. , Riviere, N. M., DeBuys, H. V., Walker, L. C., Wang, Y. and Levine, M. (2001), Topical L‐Ascorbic Acid: Percutaneous Absorption Studies. Dermatologic Surgery, 27: 137-142. DOI: 10.1046/j.1524-4725.2001.00264.x

#BeautyRecap: May 15th, 2018

Research and Technology

Emollient bath additives for the treatment of childhood eczema (BATHE): Multicentre pragmatic parallel group randomised controlled trial of clinical and cost effectiveness
BMJ

After decades without any developments, new drugs may revolutionize the treatment of atopic dermatitis
Actas Dermo-Sifiliograficas

Microscopy with ultraviolet surface excitation (MUSE): A novel approach to real ‐time inexpensive slide‐free dermatopathology
Journal of Cutaneous Pathology

Effectiveness and safety of hyaluronic acid gel with lidocaine for the treatment of nasolabial folds: A systematic review and meta-analysis
Aesthetic Plastic Surgery

Pyrus ussuriensis Maxim. leaves extract ameliorates DNCB-induced atopic dermatitis-like symptoms in NC/Nga mice
Phytomedicine

Acne scarring management: Systematic review and evaluation of the evidence
American Journal of Clinical Dermatology

Solvent-extracted wool wax: Thermotropic properties and skin efficacy
Skin Pharmacology and Physiology

Haldi ceremony – Historical use of turmeric
JAMA

Speaking with your hands – The history of the manicure
JAMA

Prevalence of sun protection use and sunburn and association of demographic and behaviorial characteristics with sunburn among US adults
JAMA

Oil from the fruits of Pterodon emarginatus Vog.: A traditional anti-inflammatory. Study combining in vivo and in silico
Journal of Ethnopharmacology

Microarray based comparative genome-wide microRNA expression profiling of skin during aging in Chinese populations
JID

Antiseptic agents elicit short-term, personalized and body site-specific shifts in resident skin bacterial communities
JID

Elastase digestion of fibronectin releases an epiviosamine peptide with fibroblast growth and survival activity
JID

The challenges of big data in dermatology
JAAD

Transforming acne care by pediatricians: An interventional cohort study
JAAD

Restoring effects of natural antI-oxidant quercetin on cellular senescent human dermal fibroblasts
The American Journal of Chinese Medicine

Humidity-regulated CLCA2 protects the epidermis from hyperosmotic stress
Science Translational Medicine

Benzoyl peroxide gel stains synthetic fabrics less than cotton
JAAD

Enhancement of cutaneous wound healing by Dsg2 augmentation of uPAR secretion
JID

The early effect of microdermabrasion on hydration and sebum level
Skin Research and Technology

Degradation of hyaluronic acid fillers using hyaluronidase in an in vivo model
Journal of Drugs in Dermatology

Chlorine dioxide complex cleanser: A new agent with rapid efficacy for keratosis pilaris
Journal of Drugs in Dermatology

Efficacy of a shower cream and a lotion with skin-identical lipids in healthy subjects with atopic dry skin
Journal of Cosmetic Dermatology

Acne scarring management: Systematic review and evaluation of the evidence
American Journal of Clinical Dermatology

Stratum corneum substantivity: drug development implications
Archives of Dermatological Research

Daily aspirin linked to melanoma risk in men
The Pharmaceutical Journal

Proanthocyanidins against oxidative stress: From molecular mechanisms to clinical applications
Biomed Res

Improvement of dermal parameters in aged skin after oral use of a nutrient supplement
Clinical, Cosmetic and Investigational Dermatology

Should you avoid sunscreens with Avobenzone?

I’ve received quite a few questions about the organic sunscreen chemical Avobenzone over the years and I wanted to shed some light on one of the most common concerns – its photodegradation in UV. These concerns are usually raised by websites that say things like, “Avobenzone degrades in the sun, resulting in the release of free radicals that may actually increase the risk for cancer.”

What these quotes often leave out is the context, which is important in understanding why Avobenzone is so commonly used in sunscreens and why it is effective.

Avobenzone or butyl methoxydibenzoyl methane is an organic sunscreen that absorbs in the UVA region and has global approval. Among the sunscreen chemicals available in the US it is the strongest and most effective UVA absorber. Avobenzone exists in two chemical forms when in solution, the enol form and the diketo (or keto) form.

When exposed to UV light some Avobenzone in the enol form can be changed into the keto form – however this is slowly reversed once Avobenzone is removed from UV light.

In its keto form Avobenzone is susceptible to photodegradation from UV light. The energy from UV light causes structural changes in the Avobenzone that can lead to breakdown products. In many cases, those breakdown products no longer effectively absorb UVA and UVB (some of them will absorb UVC). Some of these breakdown products are also thought to be irritants. The other concern is that some singlet oxygen can also be formed – a reactive oxygen species which can damage DNA and cells.

The above only relates to Avobenzone on its own though, the material that Avobenzone is dissolved into and other chemicals in the formula can change how easily Avobenzone photodegrades. Other modifications like encapsulating Avobenzone have also been tested, though the benefit is often reduced contact between Avobenzone and the skin – not photostability.

Photostabilizers generally work by absorbing energy from the Avobenzone before it becomes unstable and breaks and down. Effective photostabilizers will then be able to take this energy and dissipate it in safer forms, most often heat.

A company that produces Avobenzone, DSM Nutritional Products, performed a study testing different photostabilizers and their effect on Avobenzone’s phostability. The most commonly used and known photostabilizer of Avobenzone is the organic sunscreen chemical Octocrylene, but there are other photostabilizers that don’t act as sunscreens such as Polyester-8 and Polysilicone-15.

To perform the test, 4% Avobenzone and different photostabilizers were dissolved into a mixture of 70% ethanol, 15% caprylic/capric triglyceride, and 15% C12-15 alkyl benzoate. The solutions were placed on glass slides at a density of 2 mg/cm2 then exposed to 25 MED (Minimal Erythemal Dose, 1 MED defined by the US FDA as 200 Joules/Meter2) units of UV light. After exposure, the amount of Avobenzone remaining was determined.

What the researchers found was that the combination of 4% Avobenzone and 3-5% Octocrylene maintained 90% of the Avobenzone after 25 MEDs of UV light. Based on this, they tested different combinations of Octocrylene and other photostabilizers to see how well they stabilized Avobenzone.

They found that 3.6% Octocrylene with 4% Bis Ethylhexyloxyphenyl Methoxyphenol Triazine or 4% 4-Methylbenzylidene Camphor were able to completely stabilize the Avobenzone after 25 MED of UV.

There’s currently no global standard on photostability, different regions have their own standards. In the US as part of the Broad Spectrum test, sunscreens are pre-irradiated with 4 MED before testing.

Just like how some chemicals can increase the photostability of Avobenzone, others like Octinoxate (Octyl Methoxycinnamate) are known to speed up the photodegradation of Avobenzone. This paper is often misquoted to include Oxybenzone (2-Hydroxy-4-Methoxybenzophenone), often mischaracterized as not photostable, as a chemical that increases the photodegradation of Avobenzone, but it was included as an internal standard to allow comparison between samples – as it did not photodegrade in the experiment.

What matters when it comes to the protection offered by a sunscreen are the values and ratings determined from standardized tests like SPF, PPD, Broad Spectrum, etc and not the appearance of an ingredient on the INCI.

Basing assumptions on INCI is dangerous, as the only way to truly know is to test the products. An experiment on 6 different commercial sunscreens on their photostability highlights this. 4/6 of the organic sunscreens tested exhibited a decrease in photoprotection after UV exposure. Of the two photostable organic sunscreens one contained a combination of Avobenzone and 4-Methylbenzylidene Camphor and the other Octocrylene, Avobenzone, Mexoryl SX, and Titanium Dioxide. The one inorganic sunscreen tested was shown to be photostable after UV exposure.

Keep in mind, this study tested commercial sunscreens available in 2006, where photostability was a relatively newer concern for sunscreens and standards had not yet been defined. It was around this time that Neutrogena began marketing its Helioplex patent, a photostable combination of Avobenzone, Diethylhexyl 2,6-Naphthalate, and Oxybenzone. The Helioplex US patent was granted in 2002 and other patents for increasing photostability of Avobenzone are present as early as 1999, when the US FDA finalized the use of Avobenzone in sunscreens.

While we still do not have a global standard for photostability, the options for and knowledge to stabilize sunscreens has grown considerably. It also still very important to reapply your sunscreen throughout UV exposure, this compensates for any protection lost through photodegradation as well as physical changes in the film of sunscreen on the skin.

Source: C. Mendrok-Edinger, K. Smith, A Janssen, J. Vollhardt. The Quest for Avobenzone Stabilizers and Sunscreen Photostability, Cosmetics and Toiletries, http://www.cosmeticsandtoiletries.com/formulating/category/suncare/premium-the-quest-for-avobenzone-stabilizers-and-sunscreen-photostability-214405251.html

#BeautyRecap: May 8th, 2018

Products and Reviews

Hot Topic and Her Universe launch Star Wars beauty collection
Allure.com

A look at the Karl Lagerfeld and Model Co makeup collaboration
HarpersBazaar.com

Too Faced launching a ’90s themed anniversary lipstick collection
TeenVogue.com, Allure.com

Rupaul and Mally Beauty collaborating on a beauty capsule collection
TeenVogue.com

Innisfree launches birthstone setting powder collection
Allure.com

A review of the La Prairie White Caviar Creme Extraordinaire
Allure.com

Urban Decay to launch Lightbeam palette at Macy’s
Allure.com

A look at the best-selling face sunscreens on Amazon
Allure.com

21 self-tanners recommended by Allure
Allure.com

Corporate

Birchbox has sold majority ownership to one of its hedge fund investors after sale talks with QVC fell through
Recode.net

The Hut Group acquires Eyeko
THG.com

L’Oréal bets on demand for South Korean beauty products with the purchase of cosmetics firm Nanda
SCMP.com

How Ulta Beauty evolved its merchandising strategy to compete in a crowded market
DigiDay.com

LG Household buys Avon Japan
Nikkei.com

Skincare and Beauty

European Parliament votes to support a push towards a global animal testing ban
TheParliamentMagazine.eu

“Before you judge Asian beauty standards, try to understand them”
TeenVogue.com

“J-Beauty isn’t for millennials — and that’s exactly why they want it”
Refinery29.com

Rodan + Fields sued in class-action over eyelash enhancer
CBSNews.com

Victoria Beckham wants her fashion brand to expand into cosmetics
TheDrum.com

Danish study advises against cosmetics purchases from popular US website Wish.com
ChemicalWatch.com

Beauty Bakerie CEO Cashmere Nicole opens up about the inclusive indie makeup brand’s massive success
Allure.com

Hawaii state legislature passes sunscreen ingredients bill limiting the sale of octinoxate and oxybenzone
TeenVogue.com

Jackie Aina opens up about finding her voice in Youtube’s beauty community
Allure.com

Estée Lauder to retest products after CEO apologizes for false ad claims
Allure.com

Huda Beauty’s vagina-lightening blog post sparks controversy
Allure.com

‘Cool blond Asians’ are giving me an identity crisis
Glamour.com

Makeup artist Sir John shares some of Beyonce’s stage makeup routine
Glamour.com

More invasive plastic surgery procedures are on the rise
Allure.com

Research and Technology

Evaluation of selected skin parameters following the application of 5% vitamin C concentrate
Journal of Cosmetic Dermatology

Association between clinical characteristics, quality of life, and sleep quality in patients with periorbital hyperchromia
Journal of Cosmetic Dermatology

Fluorofenidone inhibits UVA induced senescence in human dermal fibroblasts via the mammalian target of rapamycin‐dependent SIRT1 pathway
The Journal of Dermatology

Comparative study of the bactericidal effects of indocyanine green and methyl aminolevulinate‐based photodynamic therapy on Propionibacterium acnes as a new treatment for acne
The Journal of Dermatology

Sarcoidal foreign body reaction as a severe side-effect to permanent makeup: Successful treatment with intralesional triamcinolone
Acta Dermato-Venereologica

Amelioration of lactic acid sensations in sensitive skin by stimulating the barrier function and improving the ceramide profile
Archives of Dermatological Research

Improvement of dermal parameters in aged skin after oral use of a nutrient supplement
Clinical, Cosmetic and Investigational Dermatology

Fractional sunburn threshold UVR doses generate equivalent vitamin D and DNA damage in skin types I-VI, but with epidermal DNA damage gradient correlated to skin darkness
Journal of Investigative Dermatology

Blocking or enhancing effects of some basic emollients in UVA penetration
Anais Brasileiros de Dermatologia

Melanoma underreporting among US dermatopathologists: A pilot study
Journal of Cutaneous Pathology

Chemical peels for acne vulgaris: A systematic review of randomised controlled trials
BMJ Open

Genetic customization of antiaging treatments
Journal of Clinical & Experimental Dermatology Research

Vitamin C and skin
Journal of Clinical & Experimental Dermatology Research

Preparation and characterization of ethosomal nanocarriers for transdermal delivery of cosmetic bioactive ingredient
Journal of Investigative Dermatology

Treatment of nodulocystic acne with once weekly finasteride: A pilot study
Journal of Investigative Dermatology

Over expression of opsin 3 up-regulates the activity of tyrosinase in human epidermis melanocytes co-cultured with keratinocytes in vitro
Journal of Investigative Dermatology

Superoxide dismutase 3 controls Th2 cytokine-mediated allergic inflammation through inhibition of periostin
Journal of Investigative Dermatology

Quorum sensing between bacterial species on skin protects against barrier disruption and inflammation promoted by Staphylococcus aureus
Journal of Investigative Dermatology

Targeting hyaluronan in the skin alters reactive adipogenesis in the colon
Journal of Investigative Dermatology

Role of nucleotide excision repair pathway in insulin-like growth factor-1-mediated keratinocyte photoresponses
Journal of Investigative Dermatology

Targeted activation of lymphatic vessels in inflamed skin potently inhibits skin inflammation
Journal of Investigative Dermatology

Photoprotective properties of an Entada phaseoloides seeds extract obtained by sequential enzymatic processing
Journal of Investigative Dermatology

Galectin-3 regulates UVB-induced inflammation in skin
Journal of Investigative Dermatology

Spironolactone depletes XPB protein and inhibits the UVB DNA damage response in human skin
Journal of Investigative Dermatology

Propionibacterium acnes carbohydrates from acne associated phylotypes induce distinct inflammatory response in comparison to carbohydrates from healthy phylotypes: A potential ligand implicated in acne disease pathogenesis
Journal of Investigative Dermatology

Dissecting the molecular interdependence of skin inflammation and obesity
Journal of Investigative Dermatology

The acne microbiome response to isotretinoin therapy
Journal of Investigative Dermatology

Perforin-2: A novel antimicrobial protein that kills intracellular bacteria in healthy skin, but not In chronic ulcers
Journal of Investigative Dermatology

Divergent trends in acne vulgaris interest and research a decade of lost face value in the United States
Journal of Investigative Dermatology

#BeautyRecap: May 1st, 2018

Products and Reviews

Soko Glam x COSRX Triple C Lightning celebrates anniversary with limited-edition holographic bottle
Allure.com

A look at Orveda launched by a former L’Oreal executive
NewBeauty.com

Urban Decay launches Beached Collection
TeenVogue.com

Colourpop launches Spring makeup collection with MakeupShayla
TeenVogue.com

Makeup artist Gucci Westman launches skincare and makeup line, Westman Atelier
Glamour.com

Pat McGrath labs to add lip glosses to permanent collection
Allure.com

Unicorn Snot launches holographic sunscreen
Allure.com

Dr. Barbara Sturm launches baby skincare collection, Mini Molecular
Vogue.com

A look at Spring launches at Ulta
Glamour.com

Skincare and Beauty

The women keeping Reddit’s beauty community a judgment-free space
Glamour.com

Pinterest now lets you filter by skin tone for beauty searches
Allure.com, NewBeauty.com

“The new generation of moisturizers sound completely delectable”
Elle.com

Pat McGrath shares her beauty must-haves
Elle.com

Kim Kardashian West shares her $4,500 skin-care routine
Allure.com

Photographer and creative director Zanita Whittington, “I spend $2,279 on my skin care routine, and I wouldn’t change a thing”
Glamour.com

Kourtney Kardashian visited congress to discuss regulation in the cosmetics industry
TeenVogue.com

Watch ‘100 Years of Acne Treatment’ by Allure
Allure.com

Makeup artist Bobbi Brown is reinventing herself as a wellness guru
WMagazine.com

A look at the growing cannabis trend in skincare
VanityFair.com

Asia and World

US FDA warns 3 Korean cosmetic and pharmaceutical firms for rule violations
YonhapNews.co.kr

“Jakarta’s new take on beauty standards”
JakartaGlobe.id

Korean cosmetic manufacturers are making inroads into the US
KoreaBizwire.com

‘Mini-Golden Week’ to bring shopping boom as cash-rich visitors flock to Hong Kong for holiday
SCMP.com

Study finds microplastics in Indian cosmetics
DowntoEarth.org.in

Research and Innovation

Evaluation of selected skin parameters following the application of 5% vitamin C concentrate
Journal of Cosmetic Dermatology

Urban particulate matter in air pollution penetrates into the barrier-disrupted skin and produces ROS-dependent cutaneous inflammatory response in vivo
Journal of Dermatological Science

A novel, topical, nonsteroidal, TRPV1 antagonist, PAC-14028 cream improves skin barrier function and exerts anti-inflammatory action through modulating epidermal differentiation markers and suppressing Th2 cytokines in atopic dermatitis
Journal of Dermatological Science

Antimicrobial activity of cytolytic Th17 cells targeting propionibacterium acnes
Journal of Investigative Dermatology

Exploring the relationship between stress and acne: a medical student’s perspective
Clinical, Cosmetic and Investigational Dermatology

Platelet-rich plasma versus tretinoin in treatment of striae distensae: A comparative study
Dermatologic Surgery

Mechanism of action of topical garlic on wound healing
Dermatologic Surgery

The change of body skin with aging compared to face skin in Chinese women
Journal of Investigative Dermatology

Skin neurogenic inflammation
Seminars in Immunopathology

Association between clinical characteristics, quality of life, and sleep quality in patients with periorbital hyperchromia
Journal of Cosmetic Dermatology

Platelet‐rich plasma on female androgenetic alopecia: Tested on 10 patients
Journal of Cosmetic Dermatology

Evaluation of sex ‐related changes in skin topography and structure using innovative skin testing equipment
Skin Research and Technology

Evaluation of the molecular lipid organization in millimeter ‐sized stratum corneum by synchrotron X‐ray diffraction
Skin Research and Technology

Antera 3D capabilities for pore measurements
Skin Research and Technology

Prevalence of skin allergy and irritation to cosmetics and associated factors in China: Lessons from more than 600,000 patch test case reactions from over 10,000 individual visits
Journal of Investigative Dermatology

Genetic ancestry does not influence atopic dermatitis susceptibility or disease activity among African Americans
Journal of Investigative Dermatology

Allergens or non-allergens can induce Th2-type inflammation via reactive oxygen species in keratinocytes
Journal of Investigative Dermatology

Mechanical stretch exacerbates psoriasis by promoting cell proliferation and amplifying pro-inflammatory effects of keratinocytes
Journal of Investigative Dermatology

Correlates of low sun-protection factor sunscreen users in 2000-2015: A population based study
Journal of Investigative Dermatology

Atopic dermatitis is associated with fragile homes in US children
Journal of Investigative Dermatology

Potential use of essential oil isolated from Cleistocalyx operculatus leaves as a topical dermatological agent for treatment of burn wound
Dermatology Research and Practice

#BeautyRecap: April 17th, 2018

Research and Innovation

In vitro percutaneous penetration of silver nanoparticles in pig and human skin
Regulatory Toxicology and Pharmacology

Aggregate exposure to common fragrance compounds: Comparison of the contribution of essential oils and cosmetics using probabilistic methods and the example of limonene
Food and Chemical Toxicology

New antimicrobial peptide kills drug-resistant pathogens without detectable resistance
Oncotarget

Effect of age on melanoma risk, prognosis and treatment response
Acta Dermato-Venereologica

Protective effects of glutamine on human melanocyte oxidative stress model
Indian Journal of Dermatology, Venereology and Leprology

Anti-inflammatory effect of Sacran on atopic dermatitis
Yakugaku Zasshi: Journal of the Pharmaceutical Society of Japan

Potential use of sacran hydrogels as wound dressing material
Yakugaku Zasshi: Journal of the Pharmaceutical Society of Japan

Indoor tanners as a priority population for skin cancer screening
JAMA

Skin barrier restoration and moisturization using horse oil-loaded dissolving microneedle patches
Skin Pharmacology and Physiology

Photoprotection in adolescents: What they know and how they behave
Anais Brasileiros de Dermatologia

Sun-protection behaviour, pubertal development and menarche: Factors influencing the melanocytic nevi development. The results of a observational study on 1512 children
Journal of Investigative Dermatology

Evaluation of adolescents diagnosed with acne vulgaris for quality of life and psychosocial challenges
Indian Journal of Dermatology

The effect of skin surface topography and skin colouration cues on perception of male facial age, health and attractiveness
International Journal of Cosmetic Science

Anti-inflammatory effect of Centella asiatica phytosome in a mouse model of phthalic anhydride-induced atopic dermatitis
Phytomedicine

Piper retrofractum vahl. extract, as a PPAR δ and AMPK activator, suppresses UVB-induced photoaging through mitochondrial biogenesis and MMPs inhibition in human dermal fibroblasts and hairless mice
Evidence-based Complementary and Alternative Medicine

Influence of epidermal basement membrane integrity on cutaneous permeability barrier function
Journal of Dermatological Science

Lipidomics reveals skin surface lipid abnormity in male youth acne
BJD

Dual effects of alpha-hydroxy acids on the skin
Molecules

Is biotin safe for dermatology patients?
Skin Appendage Disorders

The efficacy of a pseudo-ceramide and eucalyptus extract containing lotion on dry scalp skin
Clinical, Cosmetic and Investigational Dermatology

Barriers to adherence with acne medications and physician intervention
JAMA