The effects of topically applied glycolic acid and salicylic acid on ultraviolet radiation-induced erythema, DNA damage and sunburn cell formation in human skin

Clinically Actionable Topical Strategies for Addressing the Hallmarks of Skin Aging: A Primer for Aesthetic Medicine Practitioners

In this narrative review, we sought to provide a comprehensive overview of the mechanisms underlying cutaneous senescence, framed by the twelve traditional hallmarks of aging. These include genomic instability, telomere attrition, epigenetic alterations, loss of proteostasis, impaired macroautophagy, deregulated nutrient sensing, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, altered intercellular communication, chronic inflammation, and dysbiosis. We also examined how topical interventions targeting these hallmarks can be integrated with conventional aesthetic medicine techniques to enhance skin rejuvenation. The potential of combining targeted topical therapies against the aging hallmarks with minimally invasive procedures represents a significant advancement in aesthetic medicine, offering personalized and effective strategies to combat skin aging. The reviewed evidence paves the way for future advancements and underscores the transformative potential of integrating scientifically validated interventions targeted against aging hallmarks into traditional aesthetic practices.

Are cosmetics based on alpha hydroxy acids safe to use when purchased over the internet?

Alpha hydroxy acids (AHAs) are used in dermatology for topical treatment of skin disorders. Some regulatory bodies, including Food and Drug Administration (FDA), recommended labeling cosmetic products with sunburn alerts and proposed limitations regarding concentrations of AHAs in cosmetic products. In addition, The Cosmetic Ingredient Review (CIR) Expert Panel recommended 10% of AHAs in products as the maximal safe concentration. With a rapidly increasing trend of online purchasing of cosmetic products, it is important that their labels convey the necessary warnings and that they be harmonized with regulatory bodies regarding the recommended concentrations of AHAs. The aim of this report was to investigate whether or not the sunburn alert, as well as AHA recommendations mostly used for exfoliating cosmetic products, was visible to consumers during the online purchasing. The compliance with FDA and CIR Expert Panel standards was analyzed in the first 50 cosmetic products obtained after the conducted investigation on the Amazon.com e-commerce company website using the search term “AHA anti-aging.” It was found that exfoliating cosmetic products contained AHAs in a broad range of concentrations, from 2.5 up to 70%. Nineteen out of 50 products contained a concentration of AHAs greater than recommended. Twelve products did not contain any data at all regarding the concentration of AHAs. Sunburn alerts were present in 16 out of 50 analyzed product pages. In conclusion, more efforts should be made in providing users with information and the necessity of protection from potential complications after topical AHAs product treatments

Portulaca oleracea extract relieves skin barrier damage induced by increased photosensitivity after GA peeling

Purpose We aimed to find active substances to help relieve the symptoms caused by increased photosensitivity after alpha hydroxy acid (AHA) peeling. Methods: A questionnaire survey was provided to 66 patients who received AHA peeling therapy to understand if increased photosensitivity existed and its specific symptoms. We verified increased photosensitivity after AHA peeling by monitoring cell viability to detect the combined toxicity of glycolic acid (GA) and UVB in HaCaT cells. The ELISA method was used to determine the expression of KLK7, FLG, IL-1β, and IL-8 to correlate damage to the skin barrier and inflammation induced by GA and UVB and the relieving effects of Portulaca oleracea extract. Results: Our survey results showed that 6.06% of people were more sensitive to sunlight after AHA peeling than before. Experiments at the cellular level showed that UVB induced cytotoxicity on HaCaT cells pre-treated with GA. Combined exposure of GA and UVB induced up-regulation of KLK7 and down-regulation of FLG and increased inflammatory cytokines of IL-1β and IL-8. Portulaca oleracea extract inhibited the reduction of FLG and increased KLK7, IL-1β, and IL-8 expression caused by combined exposure. Conclusions: Our study found that combined exposure to GA and UV disrupted the skin barrier and induced significant inflammation. These results provided a theoretical basis for increased photosensitivity after chemical peeling. Portulaca oleracea extract ameliorated GA and UVB-induced impaired skin barrier function and inflammation in HaCaT cells and may have the potential to relieve photosensitivity after AHA peeling.

Oxidative-Stress-Induced Cellular Toxicity and Glycoxidation of Biomolecules by Cosmetic Products under Sunlight Exposure

Cosmetics, commonly known as ‘makeup’ are products that can enhance the appearance of the human body. Cosmetic products include hair dyes, shampoos, skincare, sunscreens, kajal, and other makeup products. Cosmetics are generally applied throughout the face and over the neck region. Sunlight has different wavelengths of light, which include UV-A, UV-B, UV-C, and other radiations. Most cosmetic products have absorption maxima (λmax) in the range of visible light and UV-R. The effect of light-induced photosensitization of cosmetic products, which results in the production of free radicals through type-I and type-II photosensitization mechanisms. Free-radicals-mediated DNA damage and oxidative stress are common consequences of cosmetic phototoxicity. Cosmetic phototoxicity may include percutaneous absorption, skin irritation, eye irritation, photosensitization, mutagenicity, and genotoxicity. Oxidative stress induces membrane lipid peroxidation, glycoxidation, and protein covalent modifications, resulting in their dysfunction. Natural antioxidants inhibit oxidative-stress-induced cosmetic toxicity. Sunlight-induced photodegradation and accumulation of cosmetic photoproducts are also a matter of serious concern. India has tropical weather conditions throughout the year and generally, a majority of human activities such as commerce, agriculture, sports, etc. are performed under bright sunlight conditions. Thus, more focused and dedicated research is warranted to explore the effects of cosmetics on oxidative stress, glycoxidation of biomolecules, and photoproducts accumulation for its total human safety.

Formulation of topical acidic products and acidification of the skin - Contribution of glycolic acid

OBJECTIVE

The acidic skin pH is one of the regulating factors of skin barrier homeostasis. Topical products as extrinsic factors which influence skin pH could be used for acidification of the skin and consequent beneficial effect. To formulate stabile and safe topical emulsion product with low pH is on-going challenge and areas interesting to explore are related to the effect of acidic products on the skin pH together with development of protocols for these studies. Aim of our work was to investigate formulations of acidic topical products with glycolic acid (GA) stabilized with long chain alkyl polyglucoside emulsifier, in regard to the specific colloidal structure of the vehicle, together with effect of products with different concentration of acidic active on skin pH.

METHODS

Investigated formulations were basic vehicle and two creams with glycolic acid (concentration 2 and 10 wt%). Microstructure was investigated by polarization microscopy, Raman spectral imaging, thermal analysis and rheological measurements. Effects on the skin were assessed by measurement of biophysical skin parameters in vivo studies (5-hour, 24-hour and 7-days). In vitro screening of antimicrobial activity was performed against bacteria Staphylococcus epidermidis.

RESULTS

Polarization micrographs and Raman images have shown that GA does not disturb the specific colloidal structure. Together with rheological and thermal analysis obtained results have shown that GA in higher concentrations contributes to vehicles' lamellar structure. In 5-hour study the mean values of skin pH ranged from 3.98-4.25 and 3.89-4.10 after application of products with smaller and higher GA concentration. GA samples lowered skin surface pH to 5 and less in 24-hour and 7-day study, with stronger effect of sample with more GA. Sample with 10% of GA had significant inhibitory effect on growth of S. epidermidis in 1:1 concentration.

CONCLUSIONS

Investigated APG emulsifier could be used as a stabilizer for acidic topical products with GA which are characterized by satisfactory safety profile. Topical products induce acidification of the skin after short- and long-term application without barrier impairment or sign of irritation. Acidification of the skin depends on presence of ingredients which are proton donors and their concentrations.

Effect of glycolic acid, phytic acid, soothing complex containing Emulsion on Hyperpigmentation and skin luminosity: A clinical evaluation

BACKGROUND

Improvement in skin luminosity and dyschromia such as postinflammatory hyperpigmentation (PIH) and actinic photodamage are leading causes for cosmetic consultation. Formulation of topical at home treatment is challenging, using a range of modalities, to help hinder or prevent inflammatory mediators without further irritating the skin. Glycolic acid is a known antioxidant; in various free acid levels, it has been introduced as a topical therapy aimed at reducing pigmentation and improving skin texture, tone, and luminosity.

METHODS

In a 12-week clinical study, a novel, topical facial emulsion containing 10% glycolic acid, 2% phytic acid, and soothing complex in emulsion was evaluated for its effectiveness in treating skin quality in American female volunteers with Fitzpatrick skin types II-VI. Efficacy evaluations were performed at pretreatment baseline, weeks 2, 4, 8, and 12, and included expert clinical grading, and self-assessment questionnaires. Cutaneous tolerability was also evaluated by assessing subjective and objective irritation of the treatment area.

RESULTS

Significant improvement in the appearance of skin PIH, hyperpigmentation, texture, and tone homogeneity was observed beginning at week 4 and continued through week 12.

CONCLUSIONS

The findings suggest that the test product is well suited for at-home skincare. It was both well-tolerated and an effective treatment option for addressing hyperpigmentation and overall skin luminosity.

Stabilization of telomere by the antioxidant property of polyphenols: Anti-aging potential

Aging is a form of a gradual loss of physiological integrity that results in impaired cellular function and ultimately increased vulnerability to disease and death. This process is a significant risk factor for critical age-related disorders such as cancer, diabetes, cardiovascular disease, and neurological conditions. Several mechanisms contribute to aging, most notably progressive telomeres shortening, which can be counteracted by telomerase enzyme activity and increasing in this enzyme activity associated with partly delaying the onset of aging. Individual behaviors and environmental factors such as nutrition affect the life-span by impact the telomerase activity rate. Healthy eating habits, including antioxidant intakes, such as polyphenols, can have a positive effect on telomere length by this mechanism. In this review, after studying the underlying mechanisms of aging and understanding the relationships between telomeres, telomerase, and aging, it has been attempted to explain the effect of polyphenols on reversing the oxidative stress and aging process.

Functional Role of Cyclin-Dependent Kinase 5 in the Regulation of Melanogenesis and Epidermal Structure

The mammalian integumentary system plays important roles in body homeostasis, and dysfunction of melanogenesis or epidermal development may lead to a variety of skin diseases, including melanoma. Skin pigmentation in humans and coat color in fleece-producing animals are regulated by many genes. Among them, microphthalmia-associated transcription factor (MITF) and paired-box 3 (PAX3) are at the top of the cascade and regulate activities of many important melanogenic enzymes. Here, we report for the first time that cyclin-dependent kinase 5 (Cdk5) is an essential regulator of MITF and PAX3. Cdk5 knockdown in mice causes a lightened coat color, a polarized distribution of melanin and hyperproliferation of basal keratinocytes. Reduced expression of Keratin 10 (K10) resulting from Cdk5 knockdown may be responsible for an abnormal epidermal structure. In contrast, overexpression of Cdk5 in sheep (Ovis aries) only produces brown patches on a white background, with no other observable abnormalities. Collectively, our findings show that Cdk5 has an important functional role in the regulation of melanin production and transportation and in normal development of the integumentary system.

Multiple Activities of Punica granatum Linne against Acne Vulgaris

Acne is a common skin condition with sebum overproduction, hyperkeratosis, Propionibacterium acnes (P. acnes) and Staphylococcus aureus, and inflammation. Punica granatum (pomegranate) is well-known for its anti-inflammatory effects; however, few studies have discussed the anti-acne effects of pomegranate. In this study, we found that pomegranate extract (PG-E) significantly reduced P. acnes-induced edema in Wistar rat ears. Therefore, an evaluation platform using multiple pathogenic mechanisms of acne was established to explore the anti-acne effects of pomegranate. Results showed that PG-E inhibited bacterial growth and lipase activity. Through a bioguided-fractionation-isolation system, four hydrolysable tannins, punicalagin (1), punicalin (2), strictinin A (3), and granatin B (4), were isolated. Compounds 1 and 2 had greater anti-bacterial activities and anti-testosterone-induced HaCaT proliferative effects than the others. Compounds 1, 3, and 4 displayed lipase inhibitory effects. Compound 4 decreased cyclooxygenase-2 expression and downregulated prostaglandin E₂ production in heat-killed P. acnes-treated RAW 246.7 cells. In conclusion, PG-E is abundant in hydrolysable tannins that display multiple anti-acne capacities, including anti-bacterial, anti-lipase, anti-keratinocyte proliferation, and anti-inflammatory actions. Hence, PG-E has great potential in the application of anti-acne and skin-care products, and punicalagin (1), the most effective component in PG-E, can be employed as a quality control marker.

Use of Polyphenolic Compounds in Dermatologic Oncology

Polyphenols are a widely used class of compounds in dermatology. While phenol itself, the most basic member of the phenol family, is chemically synthesized, most polyphenolic compounds are found in plants and form part of their defense mechanism against decomposition. Polyphenolic compounds, which include phenolic acids, flavonoids, stilbenes, and lignans, play an integral role in preventing the attack on plants by bacteria and fungi, as well as serving as cross-links in plant polymers. There is also mounting evidence that polyphenolic compounds play an important role in human health as well. One of the most important benefits, which puts them in the spotlight of current studies, is their antitumor profile. Some of these polyphenolic compounds have already presented promising results in either in vitro or in vivo studies for non-melanoma skin cancer and melanoma. These compounds act on several biomolecular pathways including cell division cycle arrest, autophagy, and apoptosis. Indeed, such natural compounds may be of potential for both preventive and therapeutic fields of cancer. This review evaluates the existing scientific literature in order to provide support for new research opportunities using polyphenolic compounds in oncodermatology.

Inorganic–Organic Nanohybrid Materials of Layered Zinc Hydroxide Nitrate with Intercalated Salicylate: Preparation, Characterization and UV-Blocking Properties

Intercalation of salicylate (Sal) into layered zinc hydroxide nitrate (ZHN) nanohybrid materials was successfully synthesized by the coprecipitation method. The effect of pH, crystallization method, temperature and time of hydrothermal treatment on preparation was investigated in detail and compared. The products were confirmed by X-ray powder diffraction (XRPD), Fourier transform infrared spectroscopy (FTIR), thermogravimetry and differential thermal analysis (TG-DTA), and scanning electron microscope (SEM). The results revealed that ZHN–Sal with pure phase and good crystallinity was obtained at pH = 6.0–6.5, 60[Formula: see text]C and 3[Formula: see text]h of temperature and time of hydrothermal treatment. The TG-DTA data indicated that the intercalated Sal had a high stability compared to the isolated. And the phases and compositions of the sample calcined at increasing temperatures were also identified by XRPD and FTIR techniques. Furthermore, ZHN–Sal exhibited an improved UV-blocking ability, showing it can be used as a potential alternative matrix for the UV blocker.

Efficacy of hydroquinone-free skin-lightening cream for photoaging

BACKGROUND

Hyperpigmentation and solar damage remains a difficult problem to treat with topical agents.

AIMS

To evaluate a novel skin-lightening complex (SLC) comprising four actives targeting melanin formation at multiple levels, namely disodium glycerophosphate, L-leucine, phenylethyl resorcinol, and undecylenoyl phenylalanine, in an oil-in-water emulsion cream.

PATIENTS/METHODS

Skin-lightening complex was evaluated in 80 female subjects of skin types I-III with at least moderate mottled hyperpigmentation. After a wash-out period of 1 month with a sunscreen, the subjects added a cream containing the SLC for 12 weeks twice daily to entire face and continued the sunscreen use.

RESULTS

Whereas there was no significant change during the wash-out period, the primary endpoint mottled hyperpigmentation decreased by 32% after the 12-week treatment period with the SLC cream. Secondary endpoints such as severity and number of lentigines, skin tone, and skin brightness also improved. In all, 57% of the subjects showed at least a moderate response, 17% did not improve, and 3% got worse after the treatment.

CONCLUSIONS

The SLC cream was well tolerated, in particular when comparing with exfoliating or peeling agent containing skin-lightening products. When used with a daily sunscreen, this study confirms that the SLC represents an alternative to hydroquinone, retinoids, and many other skin-lightening actives.

Effect of chemical peeling on the skin in relation to UV irradiation

Chemical peeling is one of the dermatological treatments available for certain cutaneous diseases and conditions or improvement of cosmetic appearance of photoaged skin. However, it needs to be clarified whether the repetitive procedure of chemical peeling on photodamaged skin is safe and whether the different chemicals used for peeling results in similar outcomes or not. In this article, we reviewed the effect of peeling or peeling agents on the skin in relation to ultraviolet (UV) radiation. The pretreatment of peeling agents usually enhance UV sensitivity by inducing increased sunburn cell formation, lowering minimum erythematous dose and increasing cyclobutane pyrimidine dimers. However, this sensitivity is reversible and recovers to normal after 1-week discontinuation. Using animals, the chronic effect of peeling and peeling agents was shown to prevent photocarcinogenesis. There is also an in vitro study using culture cells to know the detailed mechanisms of peeling agents, especially on cell proliferation and apoptotic changes via activating signalling cascades and oxidative stress. It is important to understand the effect of peeling agents on photoaged skin and to know how to deal with UV irradiation during the application of peeling agents and treatment of chemical peeling in daily life.

Effects of cosmetic formulations containing hydroxyacids on sun-exposed skin: current applications and future developments

This paper describes recent data on the effects of various skin formulations containing hydroxyacids (HAs) and related products on sun-exposed skin. The most frequently used classes of these products, such as α- and β-hydroxyacids, polyhydroxy acids, and bionic acids, are reviewed, and their application in cosmetic formulations is described. Special emphasis is devoted to the safety evaluation of these formulations, particularly on the effects of their prolonged use on sun-exposed skin. We also discuss the important contribution of cosmetic vehicles in these types of studies. Data on the effects of HAs on melanogenesis and tanning are also included. Up-to-date methods and techniques used in those explorations, as well as selected future developments in the cosmetic area, are presented.

Negligible penetration of incidental amounts of alpha-hydroxy acid from rinse-off personal care products in human skin using an in vitro static diffusion cell model

Alpha-hydroxy acids (AHAs), primarily glycolic and lactic acids, are widely used in cosmetics to alleviate dyspigmentation, photodamage, and other aging skin conditions and as pH adjusters. Glycolic acid reportedly enhances skin damage after repeated ultraviolet light exposure, e.g., increased sunburn cell formation. This study assessed potential in vitro skin penetration of lactic acid and malic acid incorporated into rinse-off personal care products, compared with rinse-off and leave-on exposures to glycolic acid (10%, pH 3.5) in a reference lotion. Radiolabeled AHA-fortified shampoo, conditioner, and lotion were evenly applied as single doses to human epidermal membranes mounted in static diffusion cells (not occluded). Exposures were 1-3 min (rinse-off) or 24 h (leave-on). Epidermal penetration of malic acid and lactic acid from the rinse-off shampoo and conditioner, respectively, was negligible, with >99% removed by rinsing, a negligible portion remaining in the stratum corneum (≤0.15%), and even less penetrating into the viable epidermis (≤0.04%). Glycolic acid penetration from the leave-on reference lotion was 1.42 μg equiv./cm2/h, with total absorbable dose recovery (receptor fluid plus epidermis) of 2.51%, compared to 0.009%, 0.003%, and 0.04% for the rinse-off reference lotion, shampoo (malic acid), and conditioner (lactic acid) exposures, respectively. Dermal penetration of AHAs into human skin is pH-, concentration-, and time-dependent. Alpha-hydroxy acids in rinse-off shampoos and conditioners are almost entirely removed from the skin within minutes by rinsing (resulting in negligible epidermal penetration). This suggests that ultraviolet radiation-induced skin effects of AHA-containing rinse-off products are negligible.

Applications of hydroxy acids: classification, mechanisms, and photoactivity

Hydroxy acids (HAs) represent a class of compounds which have been widely used in a number of cosmetic and therapeutic formulations in order to achieve a variety of beneficial effects for the skin. We review and discuss the most frequently used classes of these compounds, such as α-hydroxy acids, β-hydroxy acids, polyhydroxy acids, and bionic acids, and describe their applications as cosmetic and therapeutic agents. Special emphasis is devoted to the safety evaluation of these formulations, in particular on the effects of their prolonged use on sun-exposed skin. Furthermore, we summarize the very limited number of studies dealing with the modifications evoked by topical application of products containing HAs on photocarcinogenesis. In spite of the large number of reports on the cosmetic and clinical effects of HAs, their biological mechanism(s) of action still require more clarification. Some of these mechanisms are discussed in this article along with important findings on the effect of HAs on melanogenesis and on tanning. We also emphasize the important contribution of cosmetic vehicles in these types of studies. Thus, HAs play an important role in cosmetic formulations, as well as in many dermatologic applications, such as in treating photoaging, acne, ichthyosis, rosacea, pigmentation disorders, and psoriasis.

Growth, shrinking, and breaking of pluronic micelles in the presence of drugs and/or beta-cyclodextrin, a study by small-angle neutron scattering and fluorescence spectroscopy

The associative structures between F127 Pluronic micelles and four drugs, namely, lidocaine (LD), pentobarbital sodium salt (PB), sodium naproxen (NP), and sodium salicylate (SAL), were studied by small-angle neutron scattering (SANS). Different outcomes for the micellar aggregates are observed, which are dependent on the chemical nature of the drug and the presence of charge or otherwise: the micelles grow with LD, are hardly modified with PB, and decrease in size with both NP and SAL. The partition coefficient, determined by fluorescence spectroscopy, is directly correlated to the amount of charge, following NP approximately SAL < PB < LD. All drugs are found to lie at the interfacial layer, with a slightly deeper localization of LD and more superficial for PB. All drugs can form inclusion complexes with heptakis(2,6-di-O-methyl) beta-cyclodextrin (hep2,6 beta-CD). Hep2,6 beta-CD, as shown in previous studies (Joseph, J.; Dreiss, C. A.; Cosgrove, T. Langmuir, 2008, 24, 10005-10010; Dreiss, C. A.; Nwabunwanne, E.; Liu, R.; Brooks, N. J. Soft Matter, 2009, 5, 1888-1896), is also able to form a complex with F127, resulting in micellar breakup. In the ternary mixtures, a fine balance of forces is involved, which results in drastic micellar changes, as observed from the SANS patterns. Depending on the ratio of drug, polymer, and hep2,6 beta-CD and the nature of the interactions (which is directly linked to the drug chemical structure), the presence of drug either hinders micellar breakup by beta-CD (at high enough concentration of LD or PB) or leads to micellar growth (NP). These effects are mainly attributed to a preferential drug/beta-CD interaction (except for PB), which, at least in the conditions studied here, explains the higher beta-CD concentration needed for micellar breakup to occur.