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Glycerol and the skin: Holistic approach to its origin and functions
Abstract
Glycerol is a trihydroxy alcohol that has been included for many years in topical dermatological preparations. In addition, endogenous glycerol plays a role in skin hydration, cutaneous elasticity and epidermal barrier repair. The aquaporin-3 transport channel and lipid metabolism in the pilosebaceous unit have been evidenced as potential pathways for endogenous delivery of glycerol and for its metabolism in the skin. Multiple effects of glycerol on the skin have been reported. The diverse actions of the polyol glycerol on the epidermis include improvement of stratum corneum hydration, skin barrier function and skin mechanical properties, inhibition of the stratum corneum lipid phase transition, protection against irritating stimuli, enhancement of desmosomal degradation, and acceleration of wound-healing processes. Even an antimicrobial effect has been demonstrated. Topical application of glycerol-containing products improves skin properties in diseases characterized by xerosis and impaired epidermal barrier function, such as atopic dermatitis. The increase of epidermal hydration by glycerol is critical in skin conditions aggravated by dry and cold environmental conditions, e.g. winter xerosis. This paper provides a review on effects of glycerol on the skin, the mechanisms of its action, and the potential applications of glycerol in dermatology.
... • Glycerol acts as a humectant to restore water content and barrier function 24,29 • Evening primrose oil and grape seed oil are physiological lipids, which act as substitutes for lost natural skin lipids in the outer layers of the stratum corneum 24,30 • Fatty acids help replenish components necessary for skin barrier function 31 ...
... • Dexpanthenol contributes to barrier function recovery in dry conditions and enhances epidermal differentiation 24,34 • Argan oil, shea butter, and squalene are physiological lipids, which act as substitutes for lost natural skin lipids in the outer layers of the stratum corneum 24,30 • Glycerin acts as a humectant to restore water content and barrier function 24,29 • Niacinamide is an anti-pruritic/soothing agent 35,36 • Isopropyl isostearate is a non-physiological lipid, which contributes to normalization of the altered lipid organization/composition in the stratum corneum 24,37 Bepanthen SensiDaily (Bepanthen) ...
... • Glycerin acts as a humectant to restore water content and barrier function 24,29 • Ceramides enhance lipid integration into the skin barrier 26 • Vitamin B3 increases skin lipid production 26 • α-glucan oligosaccharide is a prebiotic to normalize skin ...
Emollients are the mainstay maintenance treatment for atopic dermatitis (AD). A novel generation of emollients, 'emollients plus', containing active, non-medicated substances, has softened the distinction between emollients and topical drugs. A literature search for selected key words was performed using PubMed. Additional papers were identified based on author expertise. Whilst the inclusion of five components of an ideal emollient has been proposed, no such consensus exists for emollients plus and they can vary markedly in their composition and modes of action for AD treatment. This could have a profound effect on their clinical efficacy. The efficacy of emollients plus in restoring and maintaining skin barrier function has been demonstrated on multiple levels, with evidence reported for their effects on the physical and biochemical, microbial, immunological, and neurosensory barriers. When selecting an appropriate AD treatment approach, the safety profiles of the available topical therapies must be carefully considered. There are several proposed treatment approaches for AD, including preventive, proactive, intermittent, and synergistic approaches. Emollients plus may be effective not only as maintenance therapy for AD, but also when used synergistically with anti-inflammatory pharmacological therapies.
... It is also used as a vehicle for many topical preparations. [31] The dermatologic uses of glycerol are summarized in Table 4. [31][32][33] ...
... It is also used as a vehicle for many topical preparations. [31] The dermatologic uses of glycerol are summarized in Table 4. [31][32][33] ...
This article describes evidence-based usage of common household items to treat dermatological diseases. We have compiled the rationale of their usage from various studies and practical ways to use items like household vinegar, bleach, and common salt, in diseases such as pseudomonas nail infections, other bacterial and fungal infections, pyogenic granuloma, etc.
... Its unique chemical property makes it prominent in the drug industry as an excellent vehicle for drug administration as it helps to maintain both moisture and smoothness of drugs (Van Rosendal et al., 2012) [29] . It also acts as a skin moisturizer, by forming a water layer on the skin surface, thereby preventing topical evaporation of water (Fluhr et al., 2008) [8] . In humans, Glycerin is widely used as a suppository to relieve occasional constipation and to clear the bowels before a rectal examination (Song, et al., 2008) [27] . ...
... Its unique chemical property makes it prominent in the drug industry as an excellent vehicle for drug administration as it helps to maintain both moisture and smoothness of drugs (Van Rosendal et al., 2012) [29] . It also acts as a skin moisturizer, by forming a water layer on the skin surface, thereby preventing topical evaporation of water (Fluhr et al., 2008) [8] . In humans, Glycerin is widely used as a suppository to relieve occasional constipation and to clear the bowels before a rectal examination (Song, et al., 2008) [27] . ...
The nutraceuticals in fruits and vegetables are among the major contributors of their therapeutic relevance to humans. This study evaluates the relevance of nutraceuticals obtained from the GC-MS analyses of dichloromethane extracts of unripe matured fruits of Musa paradisiaca, Musa acuminata and Musa balbisiana. Methodology: Unripe matured fruits of M. paradisiaca, M. acuminata and M. balbisiana harvested from their natural habitat and identified at the Plant Science Department of the University of Port Harcourt were separately washed and the epicarp were removed. The sliced mesocarp were dried and ground into fine powder. Ten grams each of the ground samples was weighed into different well stoppered bottle and 40 mls of dichloromethane was added. Each mixture was vigorously agitated and allowed to stand for 96 hours. The crude extracts collected by filtering was purified and concentrated to 2.0 ml for GC-MS analysis. Result: Results shows 97, 83, and 52 nutraceutical components in M. paradisiaca, M. acuminate and M. balbisiana respectively, with 1,4-Cyclohexadiene,1-methyl-4-(1-methylethyl)-, α-Pinene and Glycerin as highest nutraceutical components with percentage concentrations of 18.379, 11.874 and 17.889 respectively. Conclusion: The numerous therapeutic potentials of predominant nutraceuticals in these Musa species are of prominent in the development of broad-spectrum pharmaceuticals formulations for advancement of human wellbeing.
... 5 It has been shown to maintain SC integrity and enhance skin hydration through peroxisome proliferator-activated receptor α agonist (PPAR-α) that increase keratinocyte proliferation and lipid synthesis. 5 Moisturizing ingredients also help restore skin condition by forming an occlusive film on the skin surface, which controls the rate of water evaporation from the skin and by transporting hygroscopic substances capable of binding and retaining water into the SC. 6 The uses of glycerol and urea as potent endogenous humectants and moisturizers 7,8 are important components for reducing the severity of dry skin due to skin aging. Glycerol has been used as a major humectant in cosmetic products because it can spread easily on the skin and give a silky, soft, and nongreasy sensation favored by end consumers. ...
... The diverse effects of glycerol on the epidermis include increasing hydration barrier function and mechanical properties, inhibiting lipid phase transition, protecting against irritating stimuli, enhancing desmosomal degradation, and accelerating the wound-healing process. 8 Plant extracts are sometimes also added to antiaging formulations as ROS scavengers. Compounds isolated from natural products are preferred as there is a strong market trend toward formulating green and eco-friendly products. ...
We developed a facile preparation method of oil-in-water (O/ W) Pickering emulsion in an emollient formulation using basil extract (Ocimum americanum L.) as a solid particle stabilizer by fine-tuning the concentration and mixing steps of common cosmetic formulas, such as humectants (hexylene glycol and glycerol), surfactant (Tween 20), and moisturizer (urea). The hydrophobicity of the main phenolic compounds of basil extract (BE), namely, salvigenin, eupatorin, rosmarinic acid, and lariciresinol, supported high interfacial coverage to prevent coalescence of globules. Meanwhile, the presence of carboxyl and hydroxyl groups of these compounds provides active sites for stabilizing the emulsion using urea through the formation of hydrogen bonds. Addition of humectants directed the in situ synthesis of colloidal particles during emulsification. In addition, the presence of Tween 20 can simultaneously reduce the surface tension of the oil but tends to inhibit the adsorption of solid particles at high concentrations, which otherwise formed colloidal particles in water. The level of urea and Tween 20 determined the stabilization system of the O/W emulsion, whether interfacial solid adsorption (Pickering emulsion, PE) or colloidal network (CN). Variation of the partition coefficient of the phenolic compounds present in basil extract facilitated the formation of a mixed PE and CN system with better stability. The addition of excess urea induced interfacial solid particle detachment, which caused the oil droplet enlargement. The choice of stabilization system determined the control of antioxidant activity, diffusion through lipid membranes, and cellular antiaging effects in UV-B-irradiated fibroblasts. Particle sizes of less than 200 nm were found in both stabilization systems, which is beneficial for maximizing their effects. In conclusion, this study provides a technological platform to realize the demand for natural dermal cosmetic and pharmaceutical products with strong antiaging effects.
... The substrate for producing these polymers is glycerol, a non-toxic and non-irritating trihydroxy alcohol [11]. Due to the presence of three hydroxyl groups in the structure of glycerol, this compound is hygroscopic and highly soluble in water [12]. Glycerol is the molecular skeleton of fats in the human body. ...
... Glycerol is the molecular skeleton of fats in the human body. It has antibacterial activity, at which the maximum is observed at 36 • C (ca human body temperature) [11,12]. It is used in many industries such as food (as a sugar substitute for sweetening beverages), pharmaceutical (drug delivery systems) and cosmetics (as a body care substance) [11,13,14]. ...
Glycerol polyesters have recently become objects of interest in tissue engineering. Barely known so far is poly(glycerol itaconate) (PGItc), a biocompatible, biodegradable polyester. Due to the presence of a C=C electron-acceptor moiety, it is possible to post-modify the product by Michael additions to change the properties of PGItc. Thus, using PGItc as one of the elements of cellular scaffold crosslinked in situ for bone tissue regeneration seems to be a very attractive yet unexplored solution. This work aims to optimize the synthesis of PGItc to obtain derivatives with a double bond in the side chain with the highest conversion rates. The experiments were performed with itaconic anhydride and glycerol using mathematical planning of experiments according to the Box-Behnken plan without solvent and catalyst. The input variables of the process were the ratio of the OH/COOH, temperature, and reaction time. The optimised output variables were: the degree of esterification (EDtitr), the degree of esterification calculated from the analysis of 1H NMR spectra (EDNMR), and the degree of itaconic anhydride conversion—calculation based on 13C NMR spectra (%X13CNMR). In each of statistical models, the significance of the changed synthesis parameters was determined. Optimal conditions are when OH/COOH ratio is equal to 1.5, temperature is 140 °C and time of reaction is 5 h. The higher OH/COOH ratio, temperature and longer the experiment time, the higher the value of the degree of esterification and the degree of anhydride conversion.
... It is also an endogenous component of the human skin. Glycerin is transported from the dermis through the keratinocytes by a transmembrane water/glycerol transport protein, Aquaporin 3 (AQP3) [50][51][52], and its hygroscopic properties enable it to increase the water holding capacity of an impaired SC. Glycerin functions in a way similar to the skin's own natural moisturising factor (NMF), which is an essential skin process responsible for appropriate SC hydration, barrier homeostasis, desquamation and plasticity. ...
... While these active ingredients are included to treat specific symptoms or characteristics of psoriasis such as inflammation, itch and plaque build-up, the use of a moisturising base can help to dramatically improve patient outcomes [6,35]. While non-active moisturisers containing only fundamental ingredients are an important adjuvant therapy of classical psoriasis treatment modalities and used as supportive treatment in relapse-free phases [6,35,50], a moisturising base containing a topical corticosteroid will be able to not only manage the inflammation associated with psoriasis but also reduce the dryness and itch, and the accompanying scratch response that can significantly worsen disease morbidity [86]. ...
The aim of this chapter is to provide an overview of basic and tailored topical moisturisers and discuss how and why they form the backbone for the management of psoriasis. Our discussion begins by describing the main characteristics of psoriasis and by indicating how alterations in the skin’s integrity and barrier function contribute to the initial development of psoriasis and subsequent changes in psoriasis phenotype. Next, we address the evolution of topical moisturisers to ever more sophisticated and beneficial products, and describe the key biophysical effects exerted on the psoriatic skin by their active ingredients, as well as the myriad benefits offered by fundamental and specialty ingredients. Furthermore, we delineate how topical moisturiser formulation modalities can help to improve compromised skin barrier function and to alleviate the symptoms of psoriasis, cosmetically and/or therapeutically as well as discuss the associated concerns and challenges encountered along the way.
... 46 Pathways for endogenous delivery of glycerol and metabolism in the skin involve the aquaporin-3 transport channel and lipid metabolism in the pilosebaceous unit. 47 It is possible that the initial boost in skin barrier observed in this study could be from the glycerin in the placebo. The placebo effect did not appear to maintain for the course of the study. ...
Introduction
Improvement of skin barrier strength could lead to healthy and youthful appearance. “Beauty inside‐out” approach using nutraceuticals such as tomato derived carotenoids to support skin barrier strength could be of benefit to the ageing population.
Method
A panel of 60 female subjects were provided with the Lumenato capsules (containing carotenoids) or placebo capsules as nutritional supplements for 3 months. Skin health and barrier function were observed using evaporimeter which measures trans epidermal water loss (TEWL). Barrier strength was determined by study of the number of strippings required to disrupt skin barrier and barrier repair was observed in terms of TEWL a few hours after barrier disruption. Cutometer was used to observe skin firmness and elasticity. Measurements were obtained before treatment and after 4 and 12 weeks of use.
Results
Results indicated a statistically significant improvement ( p < 0.05) in skin barrier strength; a higher number of strippings were required to disrupt skin barrier after 12 weeks of supplement use. There was also a significant improvement in skin firmness and elasticity as observed with a cutometer.
Conclusion
Based on the confines and conditions of this study, oral supplementation with Lumenato resulted in significant improvement in skin barrier as well as skin firmness and elasticity.
... In comparison to the CMG-2 film, the CMG-3 film showed a 23.07 % decrease in the MC and a 23.52 % decrease in WS. Chitosan, MCC, and glycerol are highly hydrophilic materials with hygroscopic properties [61][62][63]. This is due to the presence of numerous amino (in chitosan) and hydroxyl groups in these molecules. ...
... It is indicated in the literature that glycerol moisturizes the stratum corneum of the skin, increases elasticity, protects against external irritants and improves wound healing. There is indicative data that glycerol can also have an antimicrobial effect [23,24]. Plant extracts are widely used in the world and are of great importance not only for human health but also animal health [25]. ...
Simple Summary
Bovine mastitis is one of the most widespread cow diseases, which causes high economic losses. Local treatment using natural ingredients instead of the systematic use of antibiotics can decrease the development of antimicrobial resistance. The aim of the study was to determine the physico-chemical properties, stability and antimicrobial effect of a newly formulated biocide for post-milking udder hygiene containing a thickener made from hydroxypropyl guar gum, an antiseptic chlorhexidine digluconate and teat skin-friendly components, including glycerol, Mentha Arvensis herbal oil and Aesculus hippocastanum extract. The product remains stable and homogenous for at least 12 months. The product also has good antimicrobial properties against the main mastitis pathogens, including Staphylococcus aureus, Streptococcus uberis, Escherichia coli, Candida albicans and Aspergillus niger.
Abstract
Despite much focus on mastitis as an endemic disease, clinical and subclinical mastitis remains an important problem for many herds. Reducing the usage of antibiotics for mastitis treatment allows the risks to be minimized related to the development of antimicrobial resistance and the excretion of antibiotics into the environment. The aim of the study was to determine the physico-chemical properties, stability and antimicrobial effect of a newly formulated biocide for post-milking udder hygiene containing a thickener made from hydroxypropyl guar gum, an antiseptic chlorhexidine digluconate and teat skin-friendly components including glycerol, Mentha Arvensis herbal oil and Aesculus hippocastanum extract. Hydroxypropyl guar gum was used as a thickener to provide the physical parameters and to retain the viscosity at 1438 mPa.s. The physical and chemical properties of the product, including the 12-month stability, were tested in long-term and accelerated stability studies. The product was effective against the primary mastitis pathogens, including Staphylococcus aureus, Streptococcus uberis, Escherichia coli, Candida albicans and Aspergillus niger.
... When the body requires energy, the triacylglycerol stored in the cells is broken down into glycerol and fatty acids under the action of lipase. Glycerol is decomposed by the glycolic pathway or glucose is generated by the gluconeogenic pathway to provide energy for cells, whereas fatty acids are decomposed into acetyl-CoA under sufficient oxygen supply and are thoroughly oxidized into CO2 and H2O, releasing a large amount of energy [19]. Most tissues can oxidize fatty acids, except the brain tissues, because fatty acids cannot pass through the blood-brain barrier [20]. ...
Epidemiological data have shown a positive correlation between lipid levels and tumor occurrence, such as the correlation between tumor frequency and aggressiveness, and cardiovascular disease, obesity, type 2 diabetes mellitus, and hyperinsulinemia. Therefore, reducing fat accumulation or weakening lipid metabolism may affect the carcinogenic processes of cells. Many studies have shown that traditional Chinese Medicine (TCM) has obvious advantages over traditional therapies in terms of fewer side effects, lower toxicity, and lower economic burden. This paper reviews the mechanism by which TCM regulates lipid metabolism and its antitumor effect through this regulation, with the aim of elucidating the bioactive compounds in TCM with good efficacy and few side effects that can provide promising therapeutic drugs for targeting lipid metabolism reprogramming in cancer.
... In the case of Veg Col-A, the "collagen-like" active ingredient was combined with glycerin. Glycerin is known to have good plastic properties in the skin [45]. When it is combined with Ch, its single hydrogen bonding site can break down the inter-and intramolecular hydrogen bonding networks of, thus leaving hydrophobic C-H ending groups to limit intermolecular hydrogen bond formation and allowing free motion of the chitosan chains [46]. ...
The use of animal testing in the cosmetic industry is already prohibited in more than 40 countries, including those of the EU. The pressure for it to be banned worldwide in the future is increasing, so the need for animal alternatives is of great interest today. In addition, using animals and humans in scientific research is ethically reprehensible. This study aimed to prove some of the anti-aging properties of elastin (EL), hydrolyzed collagen (HC), and two vegan collagen-like products (Veg Col) in a tri-layered chitosan membrane that was ionically crosslinked with sodium tripolyphosphate (TPP). In the first approach, as a way of representing different layers of a biological system, such as the epidermis and the two dermis sublayers, EL, HC, or Veg Col were independently introduced into the two inner layers (2L(i+b)). Their effects were compared with those of their introduction into three layers (3L). Different experiments were performed on the membrane to test its elasticity, hydration, moisture retention, and pore reduction at different concentrations of EL, HC, and Veg Col, and the results were normalized vs. a blank membrane. This new alternative to animal or human testing can be suitable for proving certain efficacy claims for active ingredients or products in the pharmaceutical, nutritional, and cosmetic fields.
... Although the presence of glycerol did not affect the gel formation, its addition needs to be optimised to individuate the optimal glycerol percentage enabling it to obtain the desired performances of the hydrogel structure. Indeed, glycerol has been included for many years in topical preparations thanks to its hydrating effect [69]; therefore, its inclusion in the hydrogel structure represented the first approach for the design of new cosmetics and cosmeceuticals. However, further work is needed to better understand fundamental aspects regarding the characteristics of HPP starch-based hydrogels, particularly, the relationship between the gel strength and the behaviour during the release of the bioactive compounds included in the formulation. ...
This work aimed to carry out a preliminary study on the release of bioactive compounds loaded into starch-based hydrogels produced by high-pressure processing (HPP). As a study case, the experiments were carried out on rice starch HPP hydrogels. Rice starch (20% w/w) and green tea extract (2% w/w), suspended in distilled water, were treated by HPP at processing conditions enabling starch gelatinisation, namely 600 MPa for 15 min at room temperature. Additional experiments were carried out on samples that were further loaded with glycerol (5% w/w). Gel formation was assessed by analysing the gelatinisation extent, structuring level, and swelling power of the samples. At the processing conditions utilised, stable hydrogels were obtained even in the presence of the extract and/or the glycerol in the starch suspension. As expected, the colour of the hydrogels formed was affected by the addition of green tea extract in the starch solution. HPP starch hydrogels were characterised by Fourier transform infrared spectroscopy (FT-IR) to determine the interactions between the different compounds utilised in the formulation. Moreover, the release kinetics of bioactive compounds from HPP rice starch hydrogels was evaluated using a vertical Franz diffusion cells system, simulating a transdermal pattern. The diffusion of bioactive compounds was measured spectrophotometrically and via HPLC analysis. A controlled release of bioactive compounds from the hydrogel structure was detected, suggesting that small molecules, such as polyphenols, positively interacted with the rice starch HPP hydrogel network that allowed a smooth and constant release of these bioactive compounds over time.
... On the other hand, phosphatidic acids, which play a key role in intracellular signaling, have been shown to directly activate pro-inflammatory protein kinases [68], and are a source of glycerol and fatty acids. Glycerol exerts beneficial effects on the epidermis by improving the hydration of the stratum corneum, the skin barrier function, and the mechanical properties of the skin, the inhibition of the lipid phase transition of the stratum corneum, the protection from irritating stimuli, the improvement of degradation desmosomal and acceleration of wound healing processes [69]. Furthermore, implementation with n-3 and n-6 PUFAs showed improvement in psoriasis and atopic dermatitis [70]. ...
As part of a project aimed at promoting the use of Calendula arvensis (Vaill.) L. (field marigold, Asteraceae) phytocomplexes in cosmeceutical formulations, the chemical composition in apolar specialized metabolites is herein elucidated. Furthermore, the screening of the cytotoxicity of the apolar extracts was evaluated in order to underline their safety as functional ingredients for cosmetics. After dissection of Calendula organs (florets, fruits, leaves, bracts, stems, and roots), ultrasound-assisted maceration in n-hexane as an extracting solvent allowed us to obtain oil-like mixtures, whose chemical composition has been highlighted through a UHPLC-ESI-QqTOF-MS/MS approach. Twenty-nine metabolites were tentatively identified; different compounds, among which the well-known poly-unsaturated fatty acids, and oxylipins and phosphatides were detected for the first time in Calendula genus. The screening of the dose-response cytotoxicity of the apolar extracts of C. arvensis highlighted the concentration of 10 μg/mL as the most suitable for the formulation of cosmeceutical preparations. Sera enriched with leaf and fruit apolar extracts turned out to have the best activity, suggesting it can be used as a new source in skin care thanks to their higher content in fatty acids.
... The areas of application for glycerol are wide-ranging. It is an essential ingredient in making skincare products such as creams in cosmetics, often because of its skin compatibility [78]. It is applied as a preservative, flavor, and consistency enhancer in food production for humans and animals [79][80][81][82][83]. ...
Falling film evaporation processes involve high fluid velocities with continuous variations in local film thickness, fluid composition, and viscosity. This contribution presents a parallel and complementary film thickness and concentration mapping distribution in falling films using a non-invasive fluorescence and near-infrared imaging technique. The experiments were performed with a mixture of glycerol/water with a mass fraction from 0 to 0.65 gglycgtotal−1 and operating ranges similar to evaporation processes. The measurement system was designed by integrating two optical measurement methods for experimental image analysis. The film thickness was evaluated using a VIS camera and high-power LEDs at 470 nm. The local glycerol concentration gglycgtotal−1 was determined using a NIR camera and high-power LEDs at 1050, 1300, 1450 and 1550 nm. A multiwavelength analysis with all NIR wavelengths was implemented with a better correlation for falling films at low flow velocity. The results show an improvement in the analysis of falling films with high flow velocities up to almost 500 mm/s by using only the 1450 nm wavelength and the fluorescence measurement. Simultaneous imaging analysis of film thickness and concentration in falling films provides further insight into understanding mass and heat transport and thus supports the optimization of falling film evaporators.
... For a more prolonged observation time, saturation and even gradual decrease of intensity are seen, which can be associated with the following two phenomena. One is due to interaction of glycerol molecules with water molecules, which finally leads to binding of approximately six molecules of water by one glycerol molecule, which is the major cosmetology effect of glycerol used for tissue hydration and softening [95]. In our case, this leads to local rehydration (swelling) of tissue and its turn back to a higher scattering condition [38]. ...
Dura mater (DM) is a connective tissue with dense collagen, which is a protective membrane surrounding the human brain. The optical clearing (OC) method was used to make DM more transparent, thereby allowing to increase in-depth investigation by confocal Raman micro-spectroscopy and estimate the diffusivity of 50% glycerol and water migration. Glycerol concentration was obtained, and the diffusion coefficient was calculated, which ranged from 9.6 × 10−6 to 3.0 × 10−5 cm2/s. Collagen-related Raman band intensities were significantly increased for all depths from 50 to 200 µm after treatment. In addition, the changes in water content during OC showed that 50% glycerol induces tissue dehydration. Weakly and strongly bound water types were found to be most concentrated, playing a major role in the glycerol-induced water flux and OC. Results show that OC is an efficient method for controlling the DM optical properties, thereby enhancing the in-depth probing for laser therapy and diagnostics of the brain. DM is a comparable to various collagen-containing tissues and organs, such as sclera of eyes and skin dermis.
... Following the principle of ecobiology to have a positive footprint on the skin ecosystem, the investigative product is a nourishing balm formulated with D-panthenol, a natural skin precursor of fatty acids and sphingolipids synthesis, 38 known to improve skin hydration and repair the skin barrier through regeneration. 39,40 In addition, it also contains glycerine, which plays a role in skin hydration, cutaneous elasticity, and epidermal barrier repair, 41 as well as lipids, such as vegetal waxes and shea oil, that are structurally similar to the lipids that occur naturally in skin. These biomimetic ingredients are known to enhance hydration and restore the skin barrier. ...
Purpose:
Xerosis and pruritus are common chronic dermatological disorders among dialysis and diabetic patients that are frequently underdiagnosed or neglected, which can impact the quality of life of these patients. This study aimed to evaluate the efficacy and safety of a specific dermo-cosmetic product in the treatment of dry skin and pruritus associated with dialysis and diabetes.
Patients and methods:
Twenty-nine dialysis patients (mean age 62 years) and 40 diabetic patients (mean age 57 years, 88% type 2) were included in two different single-center open-label uncontrolled clinical trials. All patients presented skin dryness according to the Scaling Roughness Redness and Cracks (SRRC) scale, and pruritus and/or insomnia. They applied the dermo-cosmetic product Medi-Secure Atoderm Xereane (NAOS, Laboratoire Bioderma) once or twice a day. The clinical efficacy (SRRC, pruritus, and insomnia), the skin-related quality of life (Dermatological Life Quality Index, DLQI), and the subjective efficacy were assessed at the inclusion visit and after 28 days of product application, as well as the safety.
Results:
After 28 days of application, the product significantly reduced the SRRC global score of 83% (0.9±0.8 vs 5.1±1.2) and 66% (1.4±1.2 vs 4.2±0.5), pruritus intensity of 76% (1.1±1.3 vs 4.6±2.1) and 78% (0.9±1.7 vs 4.2±2.6), and insomnia intensity of 61% (0.9±1.3 vs 2.4±2.3) and 82% (0.9±1.7 vs 4.8±2.7) in dialysis and diabetic patients, respectively. Furthermore, the product's application led to an improvement of the skin-related quality of life of 50% (5.4 vs 2.7; p<0.0001) in dialysis patients and 71% (6.6 vs 1.9; p<0.0001) in diabetic patients at D28. In addition, the product was greatly appreciated by all patients for its soothing, comforting, repairing, nourishing, and hydrating effects and was very well tolerated by the entire panels.
Conclusion:
This specific dermo-cosmetic product significantly reduces skin dryness, pruritus, and insomnia in dialysis and diabetic patients, thereby greatly improves their skin-related quality of life. By managing and avoiding bothersome symptoms associated with their disease or treatment, this ecobiological dermo-cosmetic can prevent serious complications that constitute a substantial burden on their daily life.
... Glycerol (propane-1,2,3-triol; trihydroxy propane; C 3 H 8 O 3 ) is a trihydroxy alcohol that is frequently used in topical dermatological preparations. Glycerol has a keratolytic effect, anti-irritant activity, the ability to provide elasticity to the skin, moisturizing properties, and can accelerate the process of wound healing [25]. ...
The study and discovery of bioactive compounds and new formulations as potential tools for promoting the repair of dermoepidermal tissue in wound healing is of continuing interest. We have developed a new formulation of amorphous hydrogel based on sodium alginate (NaAlg); type I collagen, isolated by the authors from silver carp tails (COL); glycerol (Gli); Aloe vera gel powder (AV); and silver nanoparticles obtained by green synthesis with aqueous Cinnamomum verum extract (AgNPs@CIN) and vitamin C, respectively. The gel texture of the amorphous hydrogels was achieved by the addition of Aloe vera, demonstrated by a rheological analysis. The evaluations of the cytotoxicity and cell proliferation capacity of the experimental amorphous hydrogels were performed against human foreskin fibroblast Hs27 cells (CRL-1634-ATCC). The developed gel formulations did not show a cytotoxic effect. The hydrogel variant containing AgNPs@CIN in a concentration of 8 µg Ag/gel formulation and hydrogel variant with vitamin C had proliferative activity. In addition, the antibacterial activity of the hydrogels was evaluated against S. aureus ATCC 6538, Ps. aeruginosa ATCC 27853, and E. coli ATCC 25922. The results demonstrated that the gel variant based on AgNPs@CIN in a concentration of 95 µg Ag/gel formulation and the hydrogel based on vitamin C show antibacterial activity. Therefore, the developed hydrogels with AgNPs@CIN and vitamin C could be promising alternatives in wound healing.
... 3,8 Glycerin and saccharide isomerate have humectant properties and increase SC hydration. 19,20 Apart from its antipruritic/ soothing effect, niacinamide increases the synthesis of natural lipids in the SC such as ceramides. 21,22 Dexpanthenol acts as a humectant, but also triggers protein/lipid synthesis and compensates for decreased SC hydration by reducing the increased stiffness of SC lipid lamellae and keratin filaments (i.e., it increases molecular mobility/fluidity of SC lipid lamellae and proteins) observed in dry skin conditions. ...
Background:
Gentle cleansing of the skin without further compromising its barrier function and moisture content, and being simultaneously devoid of adverse effects on the skin microbiome, are important features of body cleansers for atopic-prone skin sufferers. For this population, a new dexpanthenol-containing liquid cleanser (DCLC) was developed.
Methods:
Two prospective 4-week studies have been conducted. Study 1 investigated the effect of once-daily DCLC on stratum corneum (SC) hydration, transepidermal water loss (TEWL), skin pH, and skin microbiome (all on the volar forearm) in adult subjects with dry skin (N=44). Study 2 explored the cutaneous tolerability of DCLC and its effect on the microbiome biodiversity of the volar forearm skin in infants/children with atopic-prone skin (N=33, aged 6 months to 6 years). In the latter study, DCLC was applied 2-3 days/week in combination with an emollient applied at least twice-daily.
Results:
In Study 1, on day 29, the mean change in skin surface capacitance from baseline was significantly greater in the forearm test area treated with DCLC than in the contralateral test area (control) treated with water only (5.16 vs. 3.65 a.u.; p = 0.011), suggesting long-term SC hydration. DCLC use was not associated with changes in TEWL, skin pH, or microbiome biodiversity if compared to control. In Study 2, the 4-weeks' use of DCLC in combination with an emollient was well tolerated according to pediatrician skin assessment, and no flare-ups were recorded. The microbiome biodiversity did not shift during the study.
Conclusion:
These findings support the use of DCLC in subjects with atopic-prone skin.
... This was done to accelerate pain reduction since it could take up to 45 min for the pain to disappear without using this cream (44). Glycerin "neutralizes" capsaicin effects through chemical processes (hygroscopicity and water solubility) rather than inducing an analgesic effect (45) limiting its impact on the results. ...
Introduction:
Low back pain (LBP) often modifies spine motor control, but the neural origin of these motor control changes remains largely unexplored. This study aimed to determine the impact of experimental low back pain on the excitability of cortical, subcortical, and spinal networks involved in the control of back muscles.
Method:
Thirty healthy subjects were recruited and allocated to Pain (capsaicin and heat) or Control (heat) groups. Corticospinal excitability (motor-evoked potential-MEP) and intracortical networks were assessed by single- and paired-pulse transcranial magnetic stimulation, respectively. Electrical vestibular stimulation was applied to assess vestibulospinal excitability (vestibular MEP-VMEP), and the stretch reflex for excitability of the spinal or supraspinal loop (R1 and R2, respectively). Evoked back motor responses were measured before, during and after pain induction. Nonparametric rank-based ANOVA determined if pain modulated motor neural networks.
Results:
A decrease of R1 amplitude was present after the pain disappearance (p=0.01) whereas an increase was observed in the control group (p=0.03) compared to the R1 amplitude measured at pre-pain and pre-heat period, respectively (Group x Time interaction - p<0.001). No difference in MEP and VMEP amplitude was present during and after pain (p>0.05).
Conclusion:
During experimental LBP, no change in cortical, subcortical, or spinal networks was observed. After pain disappearance, the reduction of the R1 amplitude without modification of MEP and VMEP amplitude suggest a reduction in spinal excitability potentially combined with an increase in descending drives. The absence of effect during pain needs to be further explored.
... In another study using Wistar rats, the authors showed that allantoin is responsible for the healing and astringent effect, stimulating the formation of granulation tissue 36,37 . Glycerin, also present in the Solosite™ formulation, has chemotactic potential for leukocytes, favors angiogenesis, promotes autolytic debridement, keeps the burn medium moist, that is, ideal for preventing necrosis and favoring the formation of granulation tissue 38 . The presence of allantoin in these hydrogel-based dressings is very positive since it has no irritating effect when applied to the skin, as it binds to the stratum corneum, increasing the affinity of keratin with water, allowing hydration in the wound bed, and facilitating debridement of the wound which contributes to the healing process 36,37,39,40 . ...
Purpose:
To compare four commercially available hydrogel formulations in the healing of partial thickness burns experimentally induced in rats.
Methods:
Wistar rats were used, and after the burn wound induction they were divided into the following treatment groups: G1) NaCl 0.9%; G2) 1% silver sulfadiazine; G3) Debrigel™; G4) Safgel™; G5) Dersani™; G6) Solosite™. The animals were followed during seven, 14 and 30 days after the injury induction. Morphometric, macroscopic and microscopic evaluations were performed.
Results:
The treatment with Dersani™ induced better results during the inflammatory and proliferative phases of the healing process (p<0.05). The animals treated with Safgel™ presented better scaring in the remodeling phase (p<0.05), and the treatment with Dersani™ and Solosite™ induced greater wound closure (p<0.05).
Conclusions:
The hydrogel-based dressings presented beneficial outcomes in the healing of burn wounds experimentally induced in rats due to their ability in maintain the humidity of the wound, in removing the exudate, in promoting cell migration and collagen production during the different phases of the healing process.
... Enhanced localization and permeation of ITZ loaded aspasomes in cream appeared to be related to the nanosized of aspasomes and their incorporation in the cream base. Indeed, utilizing cream for topical delivery was reported to increase the solubilization capacity of lipophilic drugs, and perform an occlusive effect, potentiating their permeation (Fluhr et al., 2008). Interestingly, the prepared topically applied ITZ in the form of aspasomal cream was found to provide immediate reductions in fungal infectivity with no reported systemic adverse effects. ...
Topical conveyance of antifungal agents like itraconazole ITZ has been giving good grounds for expecting felicitous antifungal medicines. The defiance of topical delivery of this poorly water soluble and high-molecular-weight drug, however, mightily entail an adequate vehiculation. ITZ aspasomes, newer antioxidant generation of liposomes, have been designed and enclosed in a cream to ameliorate skin deposition. The proposed creams containing non-formulated ITZ or encapsulated in aspasomes (0.1% or 0.5%) were topically applied in patients with diagnosed diaper dermatitis complicated by candidiasis, tinea corporis (TC), and tinea versicolor (TVC). Placebos (void aspasomal cream and cream base) were also utilized. The obtained results for diaper rash revealed that aspasomal cream (0.5% ITZ) was eminent with respect to complete cure and negative candida culture after 10-day therapy relative to counterparts containing 0.1% ITZ aspasomes or non-formulated ITZ (0.1% and 0.5%). For tinea, the same trend was manifested in terms of ‘cleared’ clinical response in 90% of patients and absence of fungal elements after 4-week treatment. Relative to non-formulated ITZ, ITZ aspasomal cream was endorsed to be auspicious especially when ITZ concentration was lowered to half commercially available cream concentration (1%), pushing further exploitation in other dermal fungal infections.
... Glycerol serves as solvent, and humectant in drug and Scheme 1. Various glycerol conversion pathways [8]. pharmaceutical applications, such as, ointments, [31] and Cough Syrups, [32] because effect of sweet, [33] and it includes the composition of a drug Acute otitis externa due to its hygroscopic nature, [34] and the polyol glycerol helps on the improvement of stratum corneum hydration, [35] and protection against environmental conditions, and acceleration of wound-healing processes [36] and capsules and suppositories and enema [37]. And it can be used in the treatment of bacterial meningitis, [38,39] stroke, [40] or brain edema, [41] it acts as humectant, in toothpastes, lotions shaving, deodorants. ...
Glycerol is now used in a large variety of applications because the unique structure, and renewability feature, and chemical and physical properties, and because it is physiologically innocuous.
The use of glycerol for advanced organic syntheses and the conversion of glycerol into value-added chemicals is now emerging as a fascinating challenge. such as Oxidation, Esterification, Chlorination, Dehydration, Hydrogenolysis, Polymerization, Etherification, glycerol is nowadays considered one of the most relevant platform chemicals.
... Physiological lipids penetrate the SC and support the normalization of the affected lipid composition/organization [1,16]. Glycerin and niacinamide (nicotinamide) act as humectant and antipruritic/soothing agent, respectively [17][18][19]. Dexpanthenol stimulates protein/lipid synthesis and supports epidermal regeneration by enhancing epidermal differentiation. In addition, it compensates for reduced hydration by retaining/increasing molecular mobility/fluidity of the SC lipid lamellae and proteins [1,20,21]. ...
A new dexpanthenol-containing hand cream (ND-HC) was developed for people with dry, sensitive, and/or environmentally stressed hands. To explore the performance and acceptability of ND-HC, we conducted a randomized, intraindividual comparison study in 40 healthy adult subjects with sensitive and very dry skin on the hands. Instrumental measurements determined the effects on stratum corneum (SC) hydration and transepidermal water loss (TEWL) after single and/or 4 weeks’ use of ND-HC. Single and continued at least four times daily applications of ND-HC to very dry skin of the hand for 4 weeks triggered significant increases in SC hydration. On day 29, the mean change in skin capacitance from baseline was significantly greater when ND-HC was applied to the test area compared with the untreated area on the contralateral hand (12.41 vs. 4.46 a.u.; p < 0.001). Upon use of ND-HC over 4 weeks, mean TEWL decreased significantly (bilateral difference: −1.8 vs. 1.0 g/m2/h; p = 0.003), indicating an improvement in SC barrier function. A reduction in dry hand symptoms was observed over the study course. ND-HC was well tolerated and achieved a high level of acceptance and satisfaction. Our findings suggest that ND-HC complies with the required features of a state-of-the-art hand cream.
... In keratinocytes, among transmembrane proteins, AQP3 is expressed; aquaporins (AQPs) specifically transport water and glycerol into cells. Glycerol is a structural component for various lipids, and has a positive effect on elasticity and wound healing by increasing the water content of the epidermal layer [22]. Interestingly, AQP3 expression decreases with age, and contributes to skin dryness [23]. ...
Reactive oxygen species (ROS) generated by ultraviolet (UV) exposure cause skin barrier dysfunction, which leads to dry skin. In this study, the skin moisturizing effect of sphingomyelin-containing milk phospholipids in UV-induced hairless mice was evaluated. Hairless mice were irradiated with UVB for eight weeks, and milk phospholipids (50, 100, and 150 mg/kg) were administered daily. Milk phospholipids suppressed UV-induced increase in erythema and skin thickness, decreased transepidermal water loss, and increased skin moisture. Milk phospholipids increased the expression of filaggrin, involucrin, and aquaporin3 (AQP3), which are skin moisture-related factors. Additionally, hyaluronic acid (HA) content in the skin tissue was maintained by regulating the expression of HA synthesis- and degradation-related enzymes. Milk phospholipids alleviated UV-induced decrease in the expression of the antioxidant enzymes superoxidase dismutase1 and 2, catalase, and glutathione peroxidase1. Moreover, ROS levels were reduced by regulating heme oxygenase-1 (HO-1), an ROS regulator, through milk phospholipid-mediated activation of nuclear factor erythroid-2-related factor 2 (Nrf2). Collectively, sphingomyelin-containing milk phospholipids contributed to moisturizing the skin by maintaining HA content and reducing ROS levels in UVB-irradiated hairless mice, thereby, minimizing damage to the skin barrier caused by photoaging.
... This is again consistent with improvements in SC hydration and barrier function and goes beyond the changes which might be achieved by topical supplementation with a small number of specific ceramide species. Whilst the changes in skin hydration may be attributable to the glycerol and occlusives present in the lotion tested 28 , the changes in lipid composition are more likely attributable to the free fatty acids provided. Studies have previously demonstrated the ability of ex vivo skin to produce greater levels of fatty acids (and in particular elongated species) when provided with shorter chain precursors 29 . ...
Xerosis, commonly referred to as dry skin, is a common dermatological condition affecting almost a third of the population. Successful treatment of the condition traditionally involves the application of cosmetic products facilitating the moisturisation of the skin with a range of ingredients including glycerol and fatty acids. While the effectiveness of these treatments is not in question, limited information exists on the impact on the skin microbiome following use of these products and the improvement in skin hydration. Here, we describe improvements in skin barrier properties together with increased levels of cholesterol, ceramides and long-chain fatty acids following application of Body Lotion. Concomitant alterations in the skin microbiome are also seen via 16S rRNA metataxonomics, in combination with both traditional and novel informatics analysis. Following 5 weeks of lotion use, beneficial skin bacteria are increased, with improvements in microbiome functional potential, and increases in pathways associated with biosynthesis of multiple long chain fatty acids.
... This was in comparison with no staphylococcal colonization in the anterior nares of participants. Moreover, urban cases showed lower AD severity scores when only colonized with CoNS (31 [13.5-57.5]) in their anterior nares compared to no colonization at all (9 [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22], P = 0.031) (Fig 3, lower panel). When considering individual CoNS species, a significant positive association between higher objective SCORAD scores and S. capitis colonization was observed for the nonlesional skin of rural cases (48.3±10.8 vs. 39.7 ±11.5, P = 0.045, Table 4). ...
Background: Skin colonization with coagulase-negative staphylococci (CoNS) is generally beneficial, but recent investigations suggest its association with flares and atopic dermatitis (AD) severity. However, this relationship remains unclear.
Objective: To assess patterns of staphylococcal colonization and biofilm formation in toddlers with and without AD from rural and urban South African settings.
Methods: We conducted a cross-sectional study of AD-affected and non-atopic AmaXhosa toddlers from rural Umtata and urban Cape Town, South Africa. CoNS isolates were recovered from lesional, nonlesional skin samples and the anterior nares of participants. Identification of the staphylococci was achieved by MALDI-TOF mass spectrometry. The microtiter plate assay assessed in-vitro biofilm formation.
Results: CoNS and S. aureus commonly co-colonized nonlesional skin among cases (urban: 24% vs. 3%, p = 0.037 and rural 21% vs. 6%, p<0.001), and anterior nares in urban cases (24% vs. 0%, p = 0.002) than the control group. S. capitis colonization on nonlesional skin and anterior nares was positively associated with more severe disease in rural (48.3±10.8 vs. 39.7±11.5, P = 0.045) and urban cases (74.9±10.3 vs. 38.4±13, P = 0.004), respectively. Biofilm formation was similar between cases and controls, independent of rural-urban living.
Conclusion: CoNS colonization is associated with AD and disease severity and may be implicated in AD exacerbations. Studies are needed to understand their underlying pathological contribution in AD pathogenesis.
... While we are not aware of any formal studies of the ototoxicity of glycerol, its widespread use in eardrops (19) and nasal sprays argue that it is safe to use in the outer and middle ear. Glycerol is produced endogenously by sebaceous glands and is a naturally occurring component in blood plasma where it plays a role in maintaining epithelial hydration levels (29). As a result, the body is capable of transporting and metabolizing glycerol, although the local uptake rate and mechanisms for glycerol in the tympanic membrane specifically has not previously been investigated. ...
Hypothesis:
Optical clearing agents (OCAs) can render cartilage tympanoplasty grafts sufficiently transparent to permit visualization of middle ear structures in an operated ear using optical coherence tomography (OCT) imaging.
Methods:
Pieces of human tragal cartilage were treated with glycerol, a commonly used OCA. A reference reflector was imaged with OCT through the tympanoplasty as it cleared and the optical attenuation of the graft was measured. The reversibility of clearing and the dimensional changes associated with glycerol absorption were also measured. In a separate experiment, a human cadaveric temporal bone was prepared to simulate an ossiculoplasty surgery with cartilage replacement of the tympanic membrane. A partial ossicular replacement prosthesis (PORP) inserted in the ear was imaged with OCT through a 0.4mm cartilage graft optically cleared with glycerol.
Main outcome measure:
The optical attenuation of 0.4mm cartilage grafts decreased at 2.3+/-1.1 dB/min following treatment with glycerol, reaching a total decrease in attenuation of 13.6+/-5.9 dB after 7 minutes. The optical and dimensional effects of glycerol absorption were reversable following saline washout. In the temporal bone preparation, treatment of a cartilage graft with glycerol resulted in a 13 dB increase in signal-to-noise ratio and a 13 dB increase in contrast for visualizing the PORP through the graft with OCT.
Conclusions:
Optical clearing agents offer a potential pathway towards optical coherence tomography imaging of the middle ear in post-surgical ears with cartilage grafts.
Introduction
The removal of unwanted hair is a widespread grooming practice adopted by both males and females. Although many depilatory techniques are now available, shaving remains the most common, despite its propensity to irritate skin. Current techniques to investigate the impact of shaving regimes on skin health rely on costly and lengthy clinical trials, which hinge on recruitment of human volunteers and can require invasive biopsies to elucidate cellular and molecular-level changes.
Methods
Well-characterised human skin equivalent technology was combined with a commonplace dermatological technique of tape stripping, to remove cellular material from the uppermost layer of the skin ( stratum corneum ). This method of exfoliation recapitulated aspects of razor-based shaving in vitro , offering a robust and standardised in vitro method to study inflammatory processes such as those invoked by grooming practices.
Results
Tape strip insult induced inflammatory changes in the skin equivalent such as: increased epidermal proliferation, epidermal thickening, increased cytokine production and impaired barrier function. These changes paralleled effects seen with a single dry razor pass, correlated with the number of tape strips removed, and were attenuated by pre-application of shaving foam, or post-application of moisturisation.
Discussion
Tape strip removal is a common dermatological technique, in this study we demonstrate a novel application of tape stripping, to mimic barrier damage and inflammation associated with a dry shave. We validate this method, comparing it to razor-based shaving in vitro and demonstrate the propensity of suitable shave- and skin-care formulations to mitigate damage. This provides a novel methodology to examine grooming associated damage and a platform for screening potential skin care formulations.
Objective
This study aimed to assess the effect of 1,3‐propanediol at different concentrations (5%, 10%, or 15%), either applied alone or in combination with butylene glycol (5%) and/or glycerol (5%), on skin hydration and skin barrier function. The measurements were conducted using capacitance to determine skin hydration and trans epidermal water loss (TEWL) rates to evaluate skin barrier function.
Methods
A total of 30 healthy female subjects participated in the study. Capacitance and TEWL measurements were conducted at multiple time points, including before application and at 15 minutes, 2 hours, and 8 hours after the humectants were applied to the forearms of the subjects. All subjects provided written informed consent.
Results
The 1,3‐propanediol in all concentrations and in all combinations (with butylene glycol and/or glycerol) increased skin hydration and improved skin barrier function 15 minutes, 2 hours, and 8 hours after application. Glycerol increased the hydration performance of 1,3‐propanediol. The application of 1,3‐propanediol at a concentration of 15%, either alone or in combination with other humectants, reduced the TEWL to a greater extent than lower concentrations of 1,3‐propanediol. Furthermore the addition of glycerol to 1,3‐propanediol 15% improved the skin barrier and reduced TEWL when compared with 1,3‐propanediol alone and with the combination of1,3‐propanediol + butylene glycol.
Conclusion
The humectants significantly improved skin hydration and reduced TEWL throughout the 8‐hour time course. The increase in 1,3‐propanediol concentration, as well as its combination with glycerol, provided a greater benefit to the skin, improving both hydration and the skin barrier function.
Wearing masks is used as an effective way to prevent the spread of viruses. However, the effect of wearing masks on skin health requires further assessment. In this study, a non-invasive D-squame sampling method coupled with an untargeted metabolomics analysis by liquid chromatography high-resolution mass spectrometry was developed to identify the changes in the skin metabolome caused by wearing masks. D-squame method was found to have advantages over the commonly used sterile gauze method, especially for the lipids and lipid-like molecules. A total of 356 skin metabolites were putatively identified from the stratum corneum of 10 volunteers, and 17 differential metabolites were significantly downregulated after wearing surgical masks or N95 respirators. The downregulation of metabolites such as phosphatidylethanolamine and sphingomyelin might be related to hypoxia or increased skin moisture caused by wearing masks. Changes in skin metabolomics indicated a potential risk of skin barrier disruption and skin inflammation. Intermittent removal of the masks can effectively alleviate changes in the skin metabolome.
This study used Raman spectroscopy to develop a new approach to evaluate the effects of solar radiation on the stratum corneum (SC). The method measures the SC's hydration and dehydration kinetics by calculating the vOH/vCH ratio to monitor the relative water content during the drying process. The study also investigated the role of skin surface lipids (SSLs) in protecting the SC from solar radiation. The SSLs film is a complex mixture of free fatty acids, triglycerides, wax esters, squalene, free and esterified cholesterols, that play a crucial role in the skin's barrier function. The results showed that solar radiation alters the water content and balance within the SC, and SSLs provide protection by acting as an optical filter by absorbing some of the energy of the solar light. This is confirmed by high temperature gas chromatography coupled to mass spectrometry analyses by revealing a decrease in specific lipids after irradiating the SSLs. his article is protected by copyright. All rights reserved.
Objective: The effects of topical tea tree oil (TTO) on the healing of pressure ulcers (PUs) in an animal model was evaluated.
Method: To induce PUs, ischaemia-reperfusion cycles were performed by the external application of magnetic plates, with an ischaemic period of eight hours and a reperfusion period of 16 hours. Male and female Wistar rats were divided into three equally sized groups (n=20): one group received topical glycerin twice daily, another group received topical 10% (volume/volume (v/v)) TTO in glycerin twice daily; and the remaining group was untreated. The animals were assessed after one, four, seven and 14 cycles of ischaemia-reperfusion by thermal camera imaging, and then euthanised and sampled to investigate the degree of inflammation, collagen synthesis and apoptosis in the PUs.
Results: Although topical glycerin alone suppressed local inflammation and apoptosis, this suppressive effect was accentuated at all timepoints by the application of topical TTO + glycerin. Similarly, an increase in collagen synthesis was observed in the glycerin group and this was accentuated by TTO at all timepoints. Parallel to the histological findings, the local temperature had decreased significantly on days 4 and 7 for both treatment groups (glycerin and TTO+glycerin).
Conclusion: In this study, treatment with 10% (v/v) TTO in glycerin effectively suppressed skin inflammation and apoptosis, while it increased collagen synthesis during PU formation.
Objective: The effects of topical tea tree oil (TTO) on the healing of pressure ulcers (PUs) in an animal model was evaluated.
Method: To induce PUs, ischaemia-reperfusion cycles were performed by the external application of magnetic plates, with an ischaemic period of eight hours and a reperfusion period of 16 hours. Male and female Wistar rats were divided into three equally sized groups (n=20): one group received topical glycerin twice daily, another group received topical 10% (volume/volume (v/v)) TTO in glycerin twice daily; and the remaining group was untreated. The animals were assessed after one, four, seven and 14 cycles of ischaemia-reperfusion by thermal camera imaging, and then euthanised and sampled to investigate the degree of inflammation, collagen synthesis and apoptosis in the PUs.
Results: Although topical glycerin alone suppressed local inflammation and apoptosis, this suppressive effect was accentuated at all timepoints by the application of topical TTO + glycerin. Similarly, an increase in collagen synthesis was observed in the glycerin group and this was accentuated by TTO at all timepoints. Parallel to the histological findings, the local temperature had decreased significantly on days 4 and 7 for both treatment groups (glycerin and TTO+glycerin).
Conclusion: In this study, treatment with 10% (v/v) TTO in glycerin effectively suppressed skin inflammation and apoptosis, while it increased collagen synthesis during PU formation.
Glycerol (Gly) is a well-known, FDA-approved molecule posing three hydroxyl groups. Since Gly is biocompatible, here, it was aimed to prepare poly(Glycerol) (p(Gly)) particles directly for the first time for the delivery of therapeutic agents. Micrometer-sized particles of p(Gly) were successfully synthesized via the micro-emulsion method with an average size of 14.5 ± 5.6 µm. P(Gly) microparticles up to 1.0 g/mL concentrations were found biocompatible with 85 ± 1% cell viability against L929 fibroblasts. Moreover, p(Gly) microparticles were tested for hemocompatibility, and it was found that up to 1.0 mg/mL concentrations the particles were non-hemolytic with 0.4 ± 0.1% hemolysis ratios. In addition, the blood compatibility index values of the prepared p(Gly) particles were found as 95 ± 2%, indicating that these microparticles are both bio-and hemocompatible. Furthermore, Quercetin (QC) flavonoid, which possessed high antioxidant properties, was loaded into p(Gly) microparticles to demonstrate drug-carrying properties of the particles with improved bioavailability, non-toxicity, and high biocompatibility. The results of this study evidently revealed that p(Gly) particles can be directly prepared from a cost-effective and easily accessible glycerol molecule and the prepared particles exhibited good biocompatibility, hemocompatibility, and non-toxicity. Therefore, p(Gly) particles were found as promising vehicles for drug delivery systems in terms of their higher loading and release capability as well as for sustained long term release profiles.
As an on‐skin electronic device, artificial skin shows great potential in medical monitoring and personal electronics, which also holds promise to develop human‐machine merging interfaces. However, merging artificial skins with human bodies is largely restricted by the dissimilarity of material compositions in existing artificial skins and biological tissues. Naturally conductive protein is a potential material candidate for artificial skins, nevertheless, it suffers from the critical issue of dehydration which harms its proton conductivity. Inspired by the sebum membrane of human skin, herein, a protein‐based bioprotonic hydrogel (PBH) with reliable water retention ability is reported for artificial skins. The bovine serum albumin with natural proton conductivity is utilized in the PBH, and the glycerol that originally presents on human skin surface is used as an artificial sebum membrane to retain water. The PBH can act as a bioprotonic skin (B‐skin) for collecting electrophysiological signals and self‐powered sensing. Based on the B‐skin, intelligent robot and cellphone control systems are demonstrated. Compared with present artificial skins, this B‐skin is all made out of biological materials that are consistent with material components of human skin tissues including proteins, endogenous glycerol, and water. Such a B‐skin may enable the development of next‐generation human‐machine merging interfaces.
Aquaporins (AQPs) are transmembrane water channel proteins that regulate the movement of water through the plasma membrane in various tissues including cornea. The cornea is avascular and has specialized microcirculatory mechanisms for homeostasis. AQPs regulate corneal hydration and transparency for normal vision. Currently, there are 13 known isoforms of AQPs that can be subclassified as orthodox AQPs, aquaglyceroporins (AQGPs), or supraquaporins (SAQPs)/unorthodox AQPs. AQPs are implicated in keratocyte function, inflammation, edema, angiogenesis, microvessel proliferation, and the wound-healing process in the cornea. AQPs play an important role in wound healing by facilitating the movement of corneal stromal keratocytes by squeezing through tight stromal matrix and narrow extracellular spaces to the wound site. Deficiency of AQPs can cause reduced concentration of hepatocyte growth factor (HGF) leading to reduced epithelial proliferation, reduced/impaired keratocyte migration, reduced number of keratocytes in the injury site, delayed and abnormal wound healing process. Dysregulated AQPs cause dysfunction in osmolar homeostasis as well as wound healing mechanisms. The cornea is a transparent avascular tissue that constitutes the anterior aspect of the outer covering of the eye and aids in two-thirds of visual light refraction. Being the outermost layer of the eye, the cornea is prone to injury. Of the 13 AQP isoforms, AQP1 is expressed in the stromal keratocytes and endothelial cells, and AQP3 and AQP5 are expressed in epithelial cells in the human cornea. AQPs can facilitate wound healing through aid in cellular migration, proliferation, mitigation, extracellular matrix (ECM) remodeling and autophagy mechanism. Corneal wound healing post-chemical injury requires an integrative and coordinated activity of the epithelium, stromal keratocytes, endothelium, ECM, and a battery of cytokines and growth factors to restore corneal transparency. If the chemical injury is mild, the cornea will heal with normal clarity, but severe injuries can lead to partial and/or permanent loss of corneal functions. Currently, the role of AQPs in corneal wound healing is poorly understood in the context of chemical injury. This review discusses the current literature and the role of AQPs in corneal homeostasis, wound repair, and potential therapeutic target for acute and chronic corneal injuries.
The substitution of natural, bio-based and/or biodegradable polymers for those of petrochemical origin in consumer formulations has become an active area of research and development as the sourcing and destiny...
The chiral pair alkannin and shikonin and their ester derivatives (A/S), are lipophilic secondary metabolites possessing a wide spectrum of pharmacological activities. Their incorporation in lipid-based drug delivery systems can enhance their therapeutic efficacy, especially for dermal or transdermal applications. In this work, A/S in the form of oily extracts and isolated mixture of pigments from Alkanna tinctoria roots were entrapped in lipid based nanocarriers for dermal applications. In both cases, Experimental Design was carried out to evaluate the effect of process parameters on mean particle size, ζ-potential and entrapment efficiency, aiming to identify the optimum process conditions. The optimum oily extract loaded liposomes showed a mean particle size of 106 nm, ζ-potential value of −45.1 mV and entrapment efficiency (EE%) up to 72%. On the other hand, the optimum nanocarriers for the incorporation of A/S mixture showed a mean particle size of 138 nm, ζ-potential value of −15.6 mV and EE% up to 56%. The in vitro release profiles for both drug delivery systems were satisfactory and revealed that, in both cases, the release of the active pharmaceutical ingredients from the nanocarriers is controlled by diffusion. Moreover, we evaluated the effect of the optimum formulations on the viability of human dermal fibroblasts and we found that, A/S mixture loaded nanocarriers enhance cell viability. In order to assess the effect of A/S derivatives loaded nanocarriers on human fibroblasts we targeted genes related to the antioxidant cellular response, cell aging and extracellular matrix organization. The findings showed that nanocarriers induced the antioxidant response, presented a positive impact on cells’ longevity and promoted extracellular matrix organization. Based on these findings, formulated nanocarriers can be used as a potential drug delivery system for dermal applications in cosmetic products.
Skin is a complex ecosystem colonized by millions of microorganisms, including bacteria, fungi, and viruses. Skin microbiota is believed to exert critical functions in maintaining host skin health. Profiling the structure of skin microbial community is the first step to overview the ecosystem. However, the community composition is highly individualized and extremely complex. To explore the fundamental factors driving the complexity of the ecosystem, namely the selection pressures, we review the present studies on skin microbiome from the perspectives of ecology. This review summarizes the following: (1) the composition of substances/nutrients in the cutaneous ecological environment that are derived from the host and the environment, highlighting their proposed function on skin microbiota; (2) the features of dominant skin commensals to occupy ecological niches, through self-adaptation and microbe–microbe interactions; (3) how skin microbes, by their structures or bioactive molecules, reshape host skin phenotypes, including skin immunity, maintenance of skin physiology such as pH and hydration, ultraviolet (UV) protection, odor production, and wound healing. This review aims to re-examine the host–microbe interactions from the ecological perspectives and hopefully to give new inspiration to this field.
The epidermal protective functions are closely associated with skin hydration homeostasis. The understanding of different states of water binding is a rising concept in assessing topically applied formulations and their interaction within the stratum corneum (SC). In addition to global water content, primary bound water, partially bound water, and unbound water and barrier‐related lipid lateral packing and protein secondary structure can be measured by Raman spectroscopy. This study aimed to establish an in vitro SC model to evaluate differences in the efficacy of a natural sugar‐derived complex in combination with glycerol and a botanical extract in modulating SC water binding and structural proteins and barrier lipids. These compounds were selected due to their water‐binding and soothing properties. The SC water profiles were assessed at the surface and in 8 μm SC depth. After a 12 hrs. hyper‐hydration and subsequent product incubation the measurements were performed during a 6 hrs. desiccation phase. The maximal water caption and the time until reaching a steady state are measured as well as water retention and resistance against water loss. Global water content, partially bound and unbound water, as well as lipid and protein structures, were assessed with confocal Raman microspectroscopy. Both the natural sugar‐derived mixture and more pronounced, the same mixture with additional glycerol increased all three water‐binding parameters at the surface and in 8 μm SC depth at the beginning and during the desiccation phase. Further addition of botanical extract did not result in an additional increase of the water‐binding. All three formulations showed an increase in the lipid lateral packing values prevented the protein alteration as measured by ß‐sheets signal compared to blank. The present model is suited for screening studies comparing the specific effects of different compounds on hydration states. The natural sugar‐derived mixture Aquaxyl showed evidence for an improvement of all SC hydration states, lipid and protein structure which was further enhanced by the addition of glycerol 5%. This improvement was evidenced at the surface and within the SC for all hydration‐related parameters, and the lipid as well the protein structures. The addition of botanical extract phytoessence blue daisy did not show further improvement. This article is protected by copyright. All rights reserved.
The objective of this work was to study the interaction between non-thermal plasmas at atmospheric pressure and biological media in perspective of the application of this type of technology to the biomedical sector.In a first step, plasma sources were designed, realized, and characterized. These reactors implement dielectric barrier discharges in various gases in flow (synthetic air, argon, with or without water vapor admixture). The use of argon allowed the selection of conditions in which the plasma remained confined in the inter-electrode zone (relative humidity higher than 95% at room temperature) or on the contrary propagated either in free atmosphere or guided in an insulating tube in which the gas was flowing (dry argon). In the latter case, the propagation phenomenon was examined by time-resolved electrical measurements and the results were discussed with the help of previous works available in the literature. The choice of air as reactor feed-gas was also considered because of the application constraints that do not systematically allow the use of another gas.Two specific studies were conducted, one likely to find applications in the field of "plasma medicine", the other in the field of control of viral epidemics.In the latter case, the work focused on the inactivation of bacterial viruses, bacteriophages, infecting Escherichia coli. These were phage T4, a double-stranded DNA phage, and phage MS2, a single-stranded RNA phage. The phage suspensions were diluted in different buffer solutions and deposited on a water-soluble paper substrate to be exposed to different non-thermal plasma treatments. The original use of this substrate solved the difficult problem of phage particle recovery after treatment. This substrate also corresponds to an unfavorable application situation for this type of treatment (complex surface with volume diffusion of the suspension, as opposed to a smooth non-adsorbent surface such as a glass slide), leading to more realistic results that can be transposed to a real application. Phage inactivation was quantified by counting lysis plaques on E. coli culture. Thus, inactivation rates ranging from 0.66 log/min to 2 log/min were measured depending on the type of phage, the nature of the buffer solution and the type of treatment. The influence of the temperature imposed on the substrate was also examined.For the plasma medicine application, human adenocarcinoma cells (lung cancer) from five patients were treated in-vitro using the dielectric barrier reactor under two operating conditions determined by the composition of the feed-gas: plasma jet with dry argon and reactive oxidizing species (ROS) source with argon saturated with water vapor at room temperature. After a 5-minute exposure to the humid argon discharge treatment, 65% of the cells were in an apoptotic/necrotic state. For the dry argon plasma treatment, the overall proliferation and apoptosis assays did not show much efficacy. However, the dry argon plasma jet exhibited a rapid and localized effect on the cancer cells, inducing inhibition of the cells' ability to proliferate and migrate. These two operating conditions are of interest for clinical application, allowing to have a single plasma device able to deliver a very localized treatment of cells (plasma jet) or to transfer ROS on a larger surface leading to apoptosis mechanisms (humid argon discharge).
Objective
Many drugs applied to the skin with a systemic effect do not have a therapeutic effect, due to the barrier posed by the complex structure of the skin. To counteract this, absorption promoters are often added to the drug formulation. The use of albumin as an effective drug carrier is increasingly being addressed. Albumin, a natural, non-toxic polymer, can target drugs to specific cells and extend their biological half-life. This study was designed to trace the permeation of albumin after topical administration to the skin as a potential carrier of therapeutic substances.
Materials and methods
Four dermal formulations based on different polymers were prepared: methyl cellulose, sodium alginate, hypromellose and chitosan with methyl cellulose, obtaining final concentrations of albumin of 2%, 1.5% and 1%. The permeation of albumin through the skin was examined under simulated in vivo conditions.
Results
Most albumin permeated from the methylcellulose-based hydrogel. Depending on the concentration of albumin, permeation profiles were plotted and permeation rate constant and AUC(0–24 h) were calculated.
Conclusion
Methylcellulose was the optimal polymer for albumin release, whereas hypromellose was the least favorable. The concentration of albumin influences the amount and rate of permeation of this protein. The optimal concentration was 10 mg/g, from which the most albumin penetrated and the fastest. Human skin appeared to be more permeable to albumin than pig skin. However, the similar permeation profile through both membranes successfully allows the use of pig skin to track and evaluate the permeation of therapeutic substances with systemic effects.
Although evidence supports that the acne microbiome harbors a diverse range of microbes that play a vital role in the progression of acne vulgaris, the culturable microbes in the acne microbiome have not yet been largely identified. Here, we grew microbe colonies from entire acne lesions on agar plates and identified abundant Staphylococcus, Acinetobacter, and Pseudomonas species from forty selected single colonies. Staphylococcus species, including Staphylococcus epidermidis (S. epidermidis), Staphylococcus hominis (S. hominis), and Staphylococcus aureus (S. aureus), were isolated from tryptic soy broth (TSB) agar plates. However, Cutibacterium acnes (C. acnes) was predominately isolated from furazolidone-supplemented TSB agar plates. Results from gas chromatography-mass spectrometry (GC-MS) analysis revealed that, besides acetate, propionate and butyrate were the main short-chain fatty acids (SCFAs) in fermentation metabolites of C. acnes and S. epidermidis isolates, respectively. The culturable bacteria and SCFA profiles presented in this study provide a reservoir for selecting acne probiotics and developing SCFA-associated therapies against acne vulgaris.
Introduction:
Skin revitalizers are used for skin quality improving purposes. Hyaluronan hybrid cooperative complexes (HCC, Profhilo®, IBSA Pharmaceuticals) is an anti-aging treatment with a large amount of pure hyaluronic acid (HA) based on stable, cooperative, hybrid complexes. Cohesive polydensified matrix Hyaluronic Acid (CPM-HA20, Belotero Revive®, Merz Pharmaceuticals GmbH) is a slightly cross-linked HA (20 mg/ml) with glycerol (17.5 mg/ml).
Aims:
To evaluate the performance of HCC and CPM-HA20G for skin quality improvement in healthy female subjects.
Methods:
This was a split-face, single-blinded study that enrolled 24 healthy female subjects. Injections were given on three separate occasions. HCC was injected on the right cheek, while CPM-HA20G was injected on the left cheek. A battery of skin property measurements was used to evaluate the skin. Skin properties and overall satisfaction were analyzed using mixed models with the values at baseline, at week 1, week 8 and week 14 as outcome and a random effect of subject and fixed effects of treatment, visit and the treatment by visit interaction.
Results:
Both products showed evidence of effect relative to baseline on surface hydration (AU), elasticity (N/m) TEWL (g/m2 h) and melanin (AU). CPM-HA20G also showed significant evidence of effect relative to baseline on water content (%), and HCC on pore count (n) and hemoglobin (AU). Satisfaction reported by the subjects themselves showed positive trends of satisfaction over time for multiple skin properties. There were no significant differences between the tested products in the observed skin characteristics over time.
Conclusion:
These devices are effective and safe treatments for skin quality improvement, especially moisturization, with high patient satisfaction and generally mild and transient side effects.
Commensal bacteria play a major role in multiple skin functions by providing the first layer of defense against pathogens and maintaining the skin barrier. Staphylococcus epidermidis is one of the most common skin commensals. In this study, we showed that S. epidermidis ferments glycerol and uses it as a nutrient, while producing short‐chain and organic fatty acids, with the most notable being lactic acid. Lactic acid is an alpha‐hydroxy acid that inhibits the growth of pathogenic bacteria, without any negative effect on the commensal bacteria itself. Using in vivo experiments, we validated our in vitro results, showing that the skin microbiome is also capable of doing this. Finally, using 2D and 3D skin culture models, we showed that the fermentation of glycerol, mainly lactic acid, as determined by analytical methods, upregulates the expression levels of several key genes that are associated with the barrier properties of the skin. While the hydration effect of glycerol on the skin is well known, our study shows the overall benefits of glycerol on the skin microbiome, while revealing an alternate mode of action of glycerol for multiple skin benefits.
Ichthyosis is a group of genodermatosis characterized by desquamation disorders in the form of hyperkeratosis and generalized scale. Epidermolytic ichthyosis (EI) is an autosomal dominant hereditary disorder caused by mutations in keratin 1 or 10 genes. Clinical manifestations of EI are bullae, erythroderma, scales with accentuated pattern in the body folds area, and palmoplantar hyperkeratosis. Histopathological examination of EI showed hyperkeratosis, parakeratosis, vacuolization of keratinocytes, increased keratohyalin, and intraepidermal bullae. Clinical manifestation of EI could resemble many skin disorders, however with careful history taking and histopathological examination could establish the diagnosis.
Objective
To critically appraise the evidence for the role of regular moisturiser application in early life to prevent atopic dermatitis and food allergy.
Data sources
Primary peer reviewed literature.
Study selections
Original research articles based on systematic reviews, interventional studies, retrospective studies, case control and cohort studies related to the subject matter.
Results
There is good evidence to show that epicutaneous sensitisation through a defective skin barrier is important in development of atopic dermatitis (AD) and food allergy (FA). This supports moisturiser use in prevention as some of them have been proven to restore skin barrier with clear benefits in AD, while there is some limited evidence that these products may reduce allergic sensitisation. However, moisturisers have varied effects depending on ingredients and formulation, some of which are paradoxical like increasing TEWL and enhancing penetration of substances in the skin.
These effects may be responsible for some of the conflicting outcomes of prevention studies, some of which suggest that moisturisers are not useful in prevention of AD and FA, while others show a positive trend. Interestingly, there is some suggestion that moisturisers may increase the risk for allergy development perhaps through these paradoxical effects.
Conclusion
While moisturiser use is beneficial in the management of AD, current evidence suggests that it may be ineffective in prevention of AD and FA. Further studies are needed to determine the effects of moisturisation on allergic sensitisation and inflammation and to investigate if moisturiser type, frequency, duration, and age of application significantly affect the prevention and development of these allergies.
Background and Objective
Hyper-osmotic chemical agents were used to study the effects of transient tissue scattering on the remitted fluorescence emission intensity from a target placed under a tissue sample.Study Design/Materials and MethodsA fluorescent film was placed underneath in vitro and in vivo samples of hamster skin, and the remitted fluorescent signal traveling to the tissue surface was monitored over time as the tissue was treated with an osmotically active agent.ResultsThe detected fluorescent signal increased as the scattering in tissue samples was substantially reduced. The increase was greater for dimethyl sulfoxide than glucose or glycerol. It was not statistically different between in vivo skin and in vitro skin.Conclusions
The study shows how chemical agents can be used to improve the detected signal for a specific optical application. It could be useful in a number of optical therapeutic and diagnostic applications that can benefit from an increase in the penetration depth of light. Lasers Surg. Med. 29:213–220, 2001. © 2001 Wiley-Liss, Inc.
A method to increase light transport deeply into target areas of tissue would enhance both therapeutic and diagnostic laser applications. The effects of a hyperosmotic agent on the scattering properties of rat and hamster skin were investigated.
A hyperosmotic agent, glycerol, was applied in vitro and in vivo to rat and hamster skin to assess the changes in tissue optical properties. Changes in the reduced scattering coefficient after application of the agent in vitro to rat skin and after the skin has been rehydrated were assessed to evaluate the effect of the agent on tissue.
Experimental results showed a transient change in the optical properties of in vitro rat skin. A 50% increase in transmittance and decrease in diffuse reflectance occurred within 5-10 min after the introduction of anhydrous glycerol. In addition, reduction of light scattering with this technique increased depth of visibility with optical coherence tomography. Injection of glycerol under the skin allowed in vivo visualization of blood vessels.
The application of the agent reduces the amount of refractive mismatch found in the tissue and markedly reduces random scattering, thereby making the skin less turbid for visible wavelengths for a controlled period of time.
Two studies were performed to evaluate the influence of glycerol on the recovery of damaged stratum corneum barrier function. Measurements of transepidermal water loss and capacitance were conducted in a 3-day follow-up after tape stripping (study 1) and a 7-day follow-up after a barrier damage due to a repeated washing with sodium lauryl sulphate. In study 1 a faster barrier repair (transepidermal water loss) was monitored in glycerol-treated sites. Significant differences between glycerol open vs. untreated and glycerol occluded vs. untreated were observed at day 3. Stratum corneum hydration showed significantly higher values in the sites treated with glycerol+occlusion, compared with all other sites. In study 2 a faster barrier repair was seen in glycerol-treated sites, with significant differences against untreated and base-treated sites 7 days after the end of the treatment. Stratum corneum hydration showed highest values in the glycerol treated sites after 3 days of treatment. Glycerol creates a stimulus for barrier repair and improves the stratum corneum hydration; stratum corneum hydration is not strictly related to barrier homeostasis and can be optimized by different mechanisms and pathways. The observed effects were based on the modulation of barrier repair and were not biased by the humectant effect of glycerol. As the glycerol-induced recovery of barrier function and stratum corneum hydration were observed even 7 days after the end of treatment, glycerol can be regarded as a barrier stabilizing and moisturizing compound.
Gylcerol was discovered in 1779 by the Swedish chemist Scheele and is among the most effective humectant polyols such as sorbitol and mannitol. It is a versatile chemical, and moisturization is due to its high degree of hydroxyl groups, which bind and retain water. Glycerol is found in baby care products and in embalming fluids used by morticians, in glues and explosives; in throat lozenges and in suppositories. Glycerol is a colorless, viscous liquid, and stable under most conditions. Glycerin is nontoxic, easily digested, and is environmentally safe. It has a pleasant taste and odor, which makes it an ideal ingredient in food and cosmetic applications.1
Repetitive washing with 0.01 mol/l sodium lauryl sulphate solution for one week was followed by a measurable skin function disorder as evaluated by corneometry, laser Doppler flowmetry, and transepidermal water loss (TEWL) measurements. The application of commercially available barrier creams (Marly Skin®, Saniwip®, Tactosan®) as well as the application of well-defined oil-in-water emulsions containing 10% urea or 10% glycerol, respectively, significantly reduced skin function deterioration following repetitive washings. Urea and glycerol containing oil-in-water emulsions were at least as effective as the most effective commercial barrier cream Tactosan and had the additional advantage of better user acceptance.
The dependence of the effects of urea and glycerol on their concentration, the dependence of their efficacy on the vehicle and the influence of glycerol on the penetration of hydrocortisone were investigated. The study was based on the known hydrating effects of urea and glycerol on the stratum corneum when applied in basic formulations for external use, the penetration enhancing effect of urea for corticosteroids applied in dermatology, and the penetration enhancing effect of glycerol for hexyl nicotinate which was demonstrated before. 49 test persons were studied. The hydration was measured with the help of corneometry and the Skicon method. The penetration of hydrocortisone was detected by the blanching effect. The studies showed that urea and glycerol have a comparable hydrating effect in all w/o and o/w basic formulations tested. An increase in the concentration of urea from 5 to 10% did not yield any advantage, whereas 10% glycerol was more efficient than 5%, independent of the basic formulation used. Urea enhanced the penetration of steroids only in an o/w emulsion with a high water content but not in the other vehicles tested. Glycerol showed no influence on the penetration of hydrocortisone in this study.
The influence of a monotherapy with glycerol and urea, respectively, on the stratum corneum hydration against exsiccation by a tenside solution and on the skin-smoothing effect was investigated in comparison with a combination therapy with glycerol and urea. Here, an increase of 5% in the dose of urea in an oil-in-water-emulsion did not produce significant advantages with regard to the stratum corneum hydration and the protective effect against the dehydration by tenside solutions. In contrast to this an increase in the dose of glycerol of over 5% in an oil-in-water-emulsion proved to be efficient under both criteria. With regard to the stratum corneum hydration and the protective effect against exsiccation by tendides, the combination of 5% glycerin and 5% urea was superior to a monotherapy, with exception of the oil-in-water-emulsion containing 10% glycerin. With regard to the smoothing effect only the combination of 5% urea and 5% glycerin produced a significant advantage.
Objectives: To investigate in more details the mechanism of action of a newly developed skin protection cream containing 5 % glycerol and 5 % aluminium chlorohydrate as active components. Methods: In 20 healthy volunteers, the skin of the inner forearm was treated with a solvent mixture, to extract surface lipids and to create an "atopic-like" skin surface. Thereafter, a controlled washing was performed three times daily with aqueous sodium laurylsulfate (SLS) at low concentration (0.25 %). After each washing, the skin was treated with the O/W vehicle alone or containing one of the active components, with the newly developed skin protection cream, and with a commercially available standard skin protection cream. Before, during, and after treatment, the hydration of the horny layer and the transepidermal water loss (TEWL) were measured. Results and conclusion: The combination of glycerol with aluminium chlorohydrate in a suitable O/W emulsion lead to the same hydration grade of the horny layer as the O/W vehicle alone. On the other side, 5 % glycerol in the same vehicle significantly enhanced horny layer hydration. However, the skin protection effect of the combination is greater than the effect of glycerol alone. This may be an advantage if protection gloves are to be used and in individuals suffering from hyperhidrosis.
Two studies were performed to evaluate the influence of glycerol on the recovery of damaged stratum corneum barrier function. Measurements of transepidermal water loss and capacitance were conducted in a 3-day follow-up after tape stripping (study 1) and a 7-day follow-up after a barrier damage due to a repeated washing with sodium lauryl sulphate. In study 1 a faster barrier repair (transepidermal water loss) was monitored in glycerol-treated sites. Significant differences between glycerol open vs. untreated and glycerol occluded vs. untreated were observed at day 3. Stratum corneum hydration showed significantly higher values in the sites treated with glycerol + occlusion, compared with all other sites. In study 2 a faster barrier repair was seen in glycerol-treated sites, with significant differences against untreated and base-treated sites 7 days after the end of the treatment. Stratum corneum hydration showed highest values in the glycerol treated sites after 3 days of treatment. Glycerol creates a stimulus for barrier repair and improves the stratum corneum hydration; stratum corneum hydration is not strictly related to barrier homeostasis and can be optimized by different mechanisms and pathways. The observed effects were based on the modulation of barrier repair and were not biased by the humectant effect of glycerol. As the glycerol-induced recovery of barrier function and stratum corneum hydration were observed even 7 days after the end of treatment, glycerol can be regarded as a barrier stabilizing and moisturizing compound.
The epidermis functions as a barrier against the environment by means of several layers of terminally differentiated, dead keratinocytes - the cornified layer, which forms the endpoint of epidermal differentiation and death. The cornified envelope replaces the plasma membrane of differentiating keratinocytes and consists of keratins that are enclosed within an insoluble amalgam of proteins, which are crosslinked by transglutaminases and surrounded by a lipid envelope. New insights into the molecular mechanisms and the physiological endpoints of cornification are increasing our understanding of the pathological defects of this unique form of programmed cell death, which is associated with barrier malfunctions and ichthyosis.
The sorption of water by polyhydroxyalkanes and polyalkylene glycols has been studied at 35 °C and 75% relative humidity. The solubilities in water of these compounds were taken from the literature or measured by us, and found to be predictable from Yalkowski's expression and to correlate with the water sorption ability, with some notable exceptions, rationalized with reference to the configurations of the compounds in question. In very concentrated aqueous solutions all the water is bound to the polyols; in dilute solutions two or four molecules of water are bound per oxygen atom of the polyhydroxyalkanes and polyethylene glycols, respectively.
Previous studies have shown that barrier disruption increases epidermal mRNA levels of interleukin-1α (IL-1α). We used immunohistochemistry to examine IL-1α expression in hairless mouse skin under basal conditions and following barrier abrogation. In untreated mice, IL-1α was present in the dermis and nucleated epidermal layers in a diffuse, generalized pattern. In essential fatty acid deficient mice IL-1α was present in all epidermal layers and the dermis, with prominent staining in the stratum corneum. After acute barrier disruption with tape-stripping, IL-1α increased in the epidermis and dermis within 10 mm, remained elevated at 2 and 4 h, and decreased to near basal levels by 24 h. Moreover, intense, perinuclear, basal cell staining appeared at 10 mm, persisting until 4 h after barrier disruption. Since the increase in IL-1α immunostaining after acute barrier abrogation precedes the increase in mRNA, we hypothesized that the IL-1α might derive from a prefonned pool. Prolonged occlusion of normal skin, a treatment that specifically reduces epidermal mRNA levels of IL-1α, decreased basal immunostaining for IL-1α and blunted the increase in IL-1α usually seen following barrier disruption. Moreover, tape-stripping of skin, maintained ex vivo at 4°C, resulted in increased IL-1α immunostaining within the upper nucleated epidermal layers, as well as release of mature IL-1α into the medium, as measured by Western blotting and enzyme-linked immunosorbent assay. In addition, the stratum corneum attached to the tape contained IL-1α. These studies show that acute barrier disruption induces both the immediate release and dispersion of IL-1α from a pre-formed, epidermal pool, as well as increased IL-1α synthesis; both mechanisms are consistent with a role for IL-1α in the regulation of proinflammatory and homeostatic processes in the skin.
Preparations containing the humectant glycerol were applied topically to the skin of young adults, and the physical effects of glycerol on the stratum comeurn were examined using instrumental techniques. Reductions in transepidermal water loss and electrical impedance, smoothing of the skin surface profile, and an increase in the coefficient of friction were found to accompany an improvement in the expertly assessed condition of the skin. Such changes, found to last for periods in excess of eight hours, were similar to those observed transiently after the topical application of distilled water.
in the lower stratum comeurn but underwent degradation towards the upper surface of the stratum corneum. These observations contrasted with xerotic skin, which had disorganized lipid bilayers in the upper stratum corneum, although apparently normal lipid bilayers in the deeper tissue regions. Also, desmosomes remained undegraded in the upper layers of the xerotic stratum corneum, a finding corrobo- rated by western blotting showing increased levels of desmoglein 1. Chromatographic analysis of stratum comeurn lipids showed decreased ceramide and increased fatty acid levels in subjects with xerosis compared with normal individuals, particularly in the outer stratum corneum layers. Although ceramides were lost from the stratum comeurn, the increased levels of fatty acids may be due in part to the deposition of soap fatty acids. Our results support previous studies demonstrating the importance of desmosomal degradation in desquamation. Furthermore, we have been able to show changes in the normal membrane structure of intracellular lipids in the desquamating layers of the stratum comeurn. These studies also provide new insights into soap-induced winter xerosis, revealing abnormalities in stratum comeurn lipid composition and organization together with reduced desmosomal degradation.
To understand the biochemical abnormalities that underlie the reduced desquamation observed in dry skin, we analyzed corneodesmosome degradation in normal and winter xerosis skin. Western blotting of total proteins from corneocytes obtained by varnish-strippings from the legs of 56 volunteers with normal (26) or xerotic (30) skin was performed using antibodies specific for (corneo)desmosome proteins. In the whole population, the amounts of desmoglein 1 and plakoglobin were found to be correlated, but were not related to the amounts of corneodesmosin. This suggests simultaneous proteolysis for the former proteins differing from that of corneodesmosin. Neither entire desmoplakins nor any proteolysis-derived fragments were detected. The amounts of corneodesmosin, desmoglein 1, and plakoglobin detected were found to be significantly higher in xerotic compared with normal skin extracts. Conventional and freeze-fracture electron microscopy showed the absence of nonperipheral corneodesmosomes in the upper stratum corneum of normal skin but the presence of a significant number of these structures in the same layer of winter xerosis skin. These results provide a more precise description of the proteolysis of corneodesmosome components in the upper cornified layer of the epidermis. They support previous studies demonstrating the importance of corneodesmosome degradation in desquamation and reveal that the nonperipheral corneodesmosomes, which are totally degraded during maturation of the stratum corneum in normal skin, persist in winter xerosis, probably leading to abnormal desquamation.Keywords: desmosomes, epidermis, keratinocytes, proteases
Allogeneic split skin grafts are used widely in the treatment of burns. The relative simplicity of glycerol preservation of skin suggests it will be used increasingly in areas of high HIV-1 seroprevalence. The ability of glycerol preservation to inactivate HIV-1 present in skin graft infected in vitro was determined using a macrophage tropic strain HIV-1 as a cell-free virus suspension, within infected PBMCs, or within in vitro HIV-1 infected fresh cadaveric split skin. Different temperatures and concentrations of glycerol were used and infectivity determined by coculture with mitogen activated peripheral blood mononuclear cells (PBMCs) and measurement of reverse transcriptase activity after 7–10 days. Cell-free HIV-1 was inactivated within 30 min at 4°C in glycerol concentrations of 70% or higher. During similar exposure cell- or skin-associated HIV-1 titer was reduced but not eliminated with 70% and 85% glycerol at 4°C. HIV-1 was recovered consistently from skin stored in 85% glycerol at 4°C for up to 72 hr but virus isolation was infrequent after storage for more than 5 days. At 20°C or 37°C, 70% or 85% glycerol could inactivate cell- or skin-associated HIV-1 within 8 hr. The initial glycerolization procedures and the storage at 4°C eliminated effectively HIV-1 from skin. J. Med. Virol. 60:182–188, 2000. © 2000 Wiley-Liss, Inc.
In dermatology and cosmetics, moisturizers are used to soften skin. The objectives of this study were to compare the influence of three different moisturizers on skin hydration and skin mechanics by various non-invasive test methods and to determine the relationship between the methods used.
In 27 test subjects, four test areas in each were treated over 3 days, three times a day. An oil-in-water (o/w) emulsion was applied without moisturizer, the same with 10% glycerol, with 10% urea, or with 10% propylene glycol, respectively. Three hours after the last treatment results were measured by using the following instruments: Corneometer CM 820, Skicon 200, Frictionmeter, and Cutometer.
In all procedures a significant effect, in the sense of an increase in the data recorded, could be demonstrated by glycerol-treatment. During Corneometer, Frictionmeter, and Cutometer measurements, an additional unidirectional effect caused by the basic emulsion was seen. With all test methods, the influence of urea and propylene glycol was not significant compared to the basic emulsion. For all pretreatments there was a correlation between Corneometer data and Skicon data. Because of the low correlation coefficients between hydration parameters and mechanical parameters, it is to be assumed that other effects of glycerol- and basic-emulsion-treatment-independent from the hydration effect – have an additional influence on the data obtained by using the Frictionmeter and the Cutometer. This indicates that the clinical effect of emulsions should not be evaluated exclusively on the basis of electrical measurements of hydration.
Background/aims: Moisturising creams are useful treatment adjuncts in inflammatory dermatoses and have beneficial effects in the treatment of dry, scaly skin. The effects on dryness and skin permeability of a new moisturising cream with 20% glycerine was compared with its placebo and with a medicinally authorised cream with 4% urea (combined with 4% sodium chloride) in the treatment of dry skin.
Methods: Patients ( n =109) with atopic dermatitis were treated for 30 days with a moisturiser in a randomised, parallel and double‐blind fashion. Transepidermal water loss (TEWL) and skin capacitance were assessed instrumentally, and changes in the dryness of the skin were assessed by the dermatologist.
Results: No difference in TEWL was found between glycerine treatment and its placebo, whereas a lower value was found in the urea‐treated area compared to the glycerine‐treated area. No difference in skin capacitance was found. The clinical assessment of dryness showed urea to be superior to glycerine in treating the condition.
Conclusions: Moisturising creams are different, not only with respect to composition but also with respect to their influence on skin as a barrier to water in patients with atopic dermatitis.
Human cadaveric skin allografts are used in the treatment of burns and can be preserved in glycerol at high concentrations. Previously, glycerol has been attributed some antimicrobial effect. In an experimental set-up, we aimed at investigating this effect of prolonged incubation of bacteria in 85% glycerol. Staphylococcus epidermidis, Staphylococcus aureus, Pseudomonas aeruginosa, and Bacillus subtilis were incubated in 85% glycerol. The influence of duration of incubation and temperature on ultrastructure and viability were investigated. Unstressed cultures served as controls. Survival was studied after 24¿36 h and 10 days incubation in 85% glycerol at 4°C and 36°C with transmission electron microscopy (TEM) and flow cytometry using viability stains indicating membrane damage (SYTO9, propidium iodide) or esterase activity (carboxyfluorescein diacetate). TEM clearly demonstrated variability in morphological changes of bacteria suggesting different mechanisms of damage. Viability stains supported these findings with faster declining viable cell populations in 85% glycerol at 36°C compared with 4°C. Both methods demonstrated that Gram-negative species were more susceptible than Gram-positive species. In conclusion, 85% glycerol may have some additional antimicrobial effect. Temperature is an important factor herein and Gram-negatives are most susceptible. The latter finding probably reflects the difference in cell wall composition between Gram-positive and Gram-negative bacteria.
Synopsis
Topically applied water, occlusion and topically applied glycerol were used to investigate and characterize some of the changes which occur in the hydrated stratum corneum. The effects of these treatments were monitored using non‐invasive techniques under controlled conditions.
The Servomed Evaporimeter was used to determine natural water flux from the skin surface before and after treatment. The performance of the Evaporimeter in this type of study had previously been improved by attaching a paper baffle to the detector. This eliminated the variance in output caused by atmospheric movement. Experiments were carried out at temperatures below the threshold of thermal sweating and emotional sweating was minimized.
Skin surface topography was characterized by means of a new type of profilometer. The instrument's design allowed a diamond stylus to traverse the living skin surface without significantly altering its structure. Changes in skin surface roughness were further elucidated using scanning electron microscopy and macrophotography.
In vivo penetration of glycerol was assessed by chemical analysis of stratum corneum layers of treated skin. Samples were obtained by sequential stripping of the stratum corneum using adhesive tape.
Topically applied water produced only a transient benefit because of rapid evaporation. More prolonged hydration was achieved by suppressing transepidermal water loss with polyethylene film. This occlusive hyperhydration was characterized by a significant reduction in profile roughness and by a smoother macroscopic appearance.
Glycerol achieved the same effects by reducing the magnitude of the natural water flux from the skin surface and by reducing the rate of evaporation of water from applied aqueous glycerol solution or cosmetic product. Both effects were seen as the result of lowered water activity in the proximity of glycerol.
Smoothing effects of glycerol on the skin surface, and improved appearance, persisted for at least 24 h. This persistence was explained by evidence for diffusion of glycerol into the stratum corneum where it formed a reservoir.
Hydration of the skin is known to affect its barrier function and thereby exert a profound effect on penetration of both lipophilic and hydrophilic molecules. Clinically, this effect may be achieved using liberal applications of occlusive petroleum jelly and ointments. The results presented in this paper suggest that the use of humectants could achieve useful hydration using cosmetically acceptable materials.
In water soluble substances obtained by water extraction from human skin surface, free glycerol was detected by gas chromatography mass spectrometry. A selected ion monitoring method was employed to measure low concentration of free glycerol and the mean amounts were found to be about 0.7 microgram cm-2 on the cheek and 0.2 microgram cm-2 on the forearm and sole.
We recently developed a pig skin model to determine the role of corneosomes (modified desmosomes in the stratum corneum) and extracellular lipids in desquamation. The present study provides control morphometric data on the morphological changes in desmosomes and corneosomes leading to desquamation in adult pig epidermis in vivo. The extracellular space within desmosomes gradually widened from the basal to the granular layer, and decreased slightly in the stratum corneum. Mid-dense line broadening, and increased electron density of the distal light layers, coincided with membrane-coating granule extrusion in the outer granular layer. Corneocyte attachment correlated with corneosome distribution. Compactum packing was relatively tight and corneosomes were numerous. Cohesion was mainly peripheral in the disjunctum, and corneosomes were restricted to corneocyte edges. Adhesion had a tongue-and-groove appearance with corneosomes riveting corneocyte peripheries into a lipped groove on adjoining cells. Cells shed by peeling radially towards the lipped groove, and corneosomes decreased from lower to upper disjunctum. Corneosome breakdown commenced with an electron lucent band forming between the plug and lipid envelope. The plug was then unzipped from the lipid envelope and degraded. Corneosomes did not form squamosomes.
Filaggrin is a specific epidermal protein which is the precursor of the free amino acids, urocanic acid and pyrrolidone carboxylic acid which are largely responsible for the ability of the stratum corneum of the skin to remain hydrated at low environmental humidity. The distribution of filaggrin shown by immunofluorescence in the stratum corneum of the rat changed dramatically during the first hours of postnatal life. During late foetal development, filaggrin accumulated through the entire thickness of the stratum corneum, indicating that there was a block on the subsequent processing of the protein which normally would convert it to free amino acids. Immediately after birth this block was lifted and normal proteolysis of the filaggrin took place in the outer part of the stratum corneum, leaving the normal adult pattern of a thin zone of cells containing filaggrin at the bottom of the stratum corneum. This activation of filaggrin proteolysis was dependent on the drop in external water activity caused by the transition from an aqueous environment in utero to a dryer environment after birth and it could be blocked by maintaining a 100% humidity atmosphere around the newborn rat after birth. In isolated stratum corneum in vitro, filaggrin proteolysis took place only between 80 and 95% relative humidity, both higher and lower relative humidity blocked the proteolysis. Application of occlusive patches to adult rats prevented the normal proteolysis of filaggrin, indicating that this mechanism controls not only the massive filaggrin proteolysis occurring after birth but also the proteolysis occurring during normal stratum corneum maturation. The stratum corneum therefore has the ability to respond to changes in external humidity by altering the level of the stratum corneum where it converts its reserves of filaggrin into water binding amino acids, such that under humid conditions water binding components will be produced in only the most superficial stratum corneum, or even not produced at all.
Glycerol stabilizes the triple-helical structure of solubilized calf skin collagen. The equilibrium melting temperature of the protein increased linearly from 38.0 degrees C in AS buffer (0.01 M NaOAc and 0.02 M NaCl, pH 4.0) to 43.0 degrees C in AS and 6 M glycerol buffer. To understand the thermodynamic basis of this effect on the equilibrium melting temperature and the glycerol inhibition of collagen self-association, the preferential interactions of native and denatured calf skin collagens in AS buffer containing 1.5, 3, and 4.5 M glycerol were measured with a precision densimeter. The results indicated that native collagen binds glycerol preferentially whereas denatured collagen neither binds nor repels glycerol. The preferential binding of glycerol by native collagen, when interpreted in terms of the three-component solution thermodynamics, suggests that the surface interaction of native collagen with glycerol is energetically more favorable than its interaction with water. By use of the Wyman linked function, the negative chemical potential change of collagen derived from its preferential binding of glycerol can account for both the glycerol stabilization of the triple-helical structure of collagen and the inhibition of in vitro self-association of monomers into fibrils.
Low-humidity dermatoses arise in the work place as a result of low water content of the air. At a relative humidity of 10% or less, the horny layer becomes rigid and brittle. The combination of low humidity, high temperature, and, frequently, rapid air movement dehydrates the outer stratum corneum. This leads to pruritus and, finally, to low-grade eczema. A roughened, scaly stratum corneum becomes more susceptible to mechanical trauma. Microtrauma from small particles can aggravate the dry scaly dermatosis. Low-humidity lesions resolve quickly with the simple expedients of routine use of moisturizers and/or raising the relative humidity.
The mechanical parameters, work of fracture, ultimate breaking strength and elongation at fracture, were determined from the stress-strain characteristics of normal human stratum corneum conditioned in various physicochemical environments. These biomechanical properties were found to be highly dependent on the conditioning relative humidity (RH) and solvent extraction history. Over the increasing 0 to 100% RH range, untreated stratum corneum breaking strength decreased 85%, while the work of fracture increased 600%. Elongation at fracture increased from 20% at 0% RH to 190% at 100% RH. Ether extraction increased the magnitude of the breaking strength at all RH's while having little influence on RH dependence of the % elongation at fracture as compared to untreated. Sequential ether-water extraction significantly decreased the fracture elongation at the higher RH's while breaking strengths were less dependent on RH than untreated. The lower extensibility of the ether-water treated samples relative to ether extracted or untreated is consistent with the suggested role of water soluble materials being responsible for the water binding necessary for membrane flexibility. The mechanism for the influence of ether extraction on the breaking strength remains unclear.
Glycerol protects bacterial cells and transforming DNA against both x rays and 365-nm ultraviolet light, but not against 254-nm ultraviolet light. The observation reinforces the concept that 365 nm and ionizing radiation mimic each other in their biological effects and appear more closely related than are 254- and 365-nm ultraviolet light.
Moisturizers are known to have occlusive, emollient and humectant properties, all of which help to alleviate the symptoms of skin xerosis. Although the biological mode of action of moisturizers is poorly understood, the recent observation that skin xerosis is associated with incomplete desmosome digestion suggests that moisturizers improve the desquamation process in such conditions. To examine the possibility that certain moisturize