Showing papers in "International Journal of Cosmetic Science in 2007"

A short history of sweat gland biology

Abstract: Synopsis The axilla, especially its microflora and axillary sweat glands as well as their secretions, is the main target of cosmetic compositions such as deodorants or antiperspirants. There are three types of sweat glands present in the axillary skin, namely apocrine, eccrine and apoeccrine sweat glands. Here, we provide an overview of the morphological, structural and functional characteristics of the different gland types and present techniques that allow their clear distinction. Moreover, we describe different forms of perspiration as physical reactions to external and internal stimuli. Resume Les glandes sudoripares axillaires et leurs secretions sont les points d'application principaux des produits antitranspirants et deodorants. Dans la peau axillaire, il y a trois formes differentes de glandes sudoripares appelees apocrines, eccrines et apoeccrines. Nous donnons une vue d'ensemble des proprietes fonctionnelles, morphologiques et structurelles des differentes glandes et presentons des techniques qui permettent leur distinction. Nous decrivons egalement les differents modes de transpiration corporelle entant que reactions physiques aux stimuli externes et internes.

Nail biology and nail science

Abstract: The nail plate is the permanent product of the nail matrix. Its normal appearance and growth depend on the integrity of several components: the surrounding tissues or perionychium and the bony phalanx that are contributing to the nail apparatus or nail unit. The nail is inserted proximally in an invagination practically parallel to the upper surface of the skin and laterally in the lateral nail grooves. This pocket-like invagination has a roof, the proximal nail fold and a floor, the matrix from which the nail is derived. The germinal matrix forms the bulk of the nail plate. The proximal element forms the superficial third of the nail whereas the distal element provides its inferior two-thirds. The ventral surface of the proximal nail fold adheres closely to the nail for a short distance and forms a gradually desquamating tissue, the cuticle, made of the stratum corneum of both the dorsal and the ventral side of the proximal nail fold. The cuticle seals and therefore protects the ungual cul-de-sac. The nail plate is bordered by the proximal nail fold which is continuous with the similarly structured lateral nail fold on each side. The nail bed extends from the lunula to the hyponychium. It presents with parallel longitudinal rete ridges. This area, by contrast to the matrix has a firm attachment to the nail plate and nail avulsion produces a denudation of the nail bed. Colourless, but translucent, the highly vascular connective tissue containing glomus organs transmits a pink colour through the nail. Among its multiple functions, the nail provides counterpressure to the pulp that is essential to the tactile sensation involving the fingers and to the prevention of the hypertrophy of the distal wall tissue, produced after nail loss of the great toe nail.

A method for broad spectrum classification of sunscreens.

Abstract: Synopsis A method is described and evaluated for classifying sunscreen products into different broad spectrum categories. The method is based on spectrophotometric analysis of products applied to a suitable substrate and obviates the need for human or animal studies utilizing clinical endpoints which may be of dubious value in relation to protection from sun exposure. The absorbance spectrum obtained by spectrophotometric assay is reduced to a single index by determining that wavelength lambda(c) where the area under the spectrum from 290 nm (the approximate lower wavelength limit of terrestrial sunlight) to lambda(c) is 90% of the integral of the absorbance spectrum from 290 to 400 nm. A five-point scale is used to classify products as follows: The method makes no underlying assumptions about the form of action spectra for either acute or chronic photobiological damage. However, acknowledgement is made of the fact that the efficiency of ultraviolet radiation to induce a given photobiological endpoint tends to decrease with increasing wavelength by adopting wavelength intervals for classifying the Broad Spectrum Rating which increase in an approximately logarithmic manner.

Nanostructured lipid carriers as novel carrier for sunscreen formulations

Abstract: Incorporation of sunscreens into lipid carriers with an increased sun protection factor (SPF) has not yet been fully accomplished. In the present paper, the effectiveness of a sunscreen mixture, incorporated into the novel topical delivery systems, i.e. solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC), used as ultraviolet (UV) protector enhancers with a distinctly higher loading capacity has been developed and evaluated. SLN and NLC were produced by hot high pressure homogenization technique in lab scale production. Size distribution and storage stability of formulations were investigated by laser diffractometry and photon correlation spectroscopy. Nanoparticles were characterized by their melting and recrystallization behaviour recorded by differential scanning calorimetry. Lipid nanoparticles produced with a solid matrix (SLN and NLC) were established as a UV protection system. The loading capacities for molecular sunscreens reported before now were in the range of 10-15%. It was possible to load NLC with up to 70% with molecular sunscreen, which is appropriate to obtain high SPFs with this novel UV protection system. The developed formulations provide a beneficial alternative to conventional sunscreen formulations. The UV protective efficacy of the lipid particles varied with the nature of lipid and UV wavelength.

Anti‐microbial and ‐inflammatory activity and efficacy of phytosphingosine: an in vitro and in vivo study addressing acne vulgaris

Abstract: Lipids are important constituents of the human epidermis. Either free and organized into broad lipid bilayers in the intercorneocytes spaces, or covalently bound to the corneocyte envelope, they play a crucial role in permeability barrier function and are major contributors to cutaneous anti-microbial defense. Free sphingoid bases are a recent addition to this family of active lipids, which emerged from studies of breakdown products from ceramides. Phytosphingosine (PS) is a lipid occurring naturally in the stratum corneum, both in its free form and as a part of the major fraction of ceramides. The biotechnological production of PS patented by Degussa yields to PS with the correct configuration present in the skin. So, application of a PS containing formulation leads to its integration into the natural lipid structures of the skin. In acne, different pathogenetic factors contribute to the inflammation process, defect in keratinization, increased sebaceous gland activity and increased colonization of Propionibacterium acnes. The results of in vitro and in vivo studies confirm the previous reports on strong anti-microbial effectiveness of skin-identical PS produced by Degussa in vitro and in vivo. In addition, PS shows excellent clinical results in the context of skin care in acne, based on both anti-inflammatory and anti-microbial activity. These results demonstrate the potential of PS to enhance or complement existing acne therapies acting as an active cosmetic ingredient.

Update on peptidylarginine deiminases and deimination in skin physiology and severe human diseases.

Abstract: Deimination (or citrullination) is a recently described post-translational modification, but its consequences are not yet well understood. It is catalysed by peptidylarginine deiminases (PADs). These enzymes transform arginyl residues involved in a peptidyl link into citrullyl residues in a calcium-dependent manner. Several PAD substrates have already been identified like filaggrin and keratins K1 and K10 in the epidermis, trichohyalin in hair follicles, but also ubiquitous proteins like histones. PADs act in a large panel of physiological functions as cellular differentiation or gene regulation. It has been suggested that deimination plays a role in many major diseases such as rheumatoid arthritis, multiple sclerosis, Alzheimer's disease and psoriasis. Five human genes (PADIs), encoding five highly conserved paralogous enzymes (PAD1-4 and 6), have been characterized. These genes are clustered in a single locus, at 1p35-36 in man. Only PAD1-3 are expressed in human epidermis. PADs seem to be controlled at transcriptional, translational and activity levels and they present particular substrate specificities. In this review, we shall discuss these main biochemical, genetic and functional aspects of PADs together with their pathophysiological implications.

Profiling of serine protease activities in human stratum corneum and detection of a stratum corneum tryptase-like enzyme

Abstract: Synopsis Seasonal variation in stratum corneum (SC) biophysical and biological characteristics has been described previously. In particular, the winter season has been shown to affect more severely the properties of facial skin compared with forearm skin. Moreover, when compromised, such as in dry skin conditions, facial SC has been shown to contain increased inflammatory cytokines and proteases. Nevertheless, there have been no comparative studies of the activities and depth activity of several proteases in the SC on different body sites and at different times of the year. In this study, we examined the distribution of key serine protease activities (kallikrein 5, kallikrein 7, urokinase, plasmin and a tryptase-like enzyme) in different layers of the SC on the cheek and the forearm by analysis of consecutive tape strippings of healthy Caucasian subjects during winter and summer. The protein content of the tape strippings was quantified by absorption measurements with a recently developed and novel infrared densitometer SquameScanTM 850A while the SC enzyme activities were determined using fluorogenic peptide substrates. Transepidermal water loss (TEWL), skin pH and skin hydration were higher on the cheek than on the forearm. In the same way, the activity of the inflammatory-related proteases plasmin, urokinase and tryptase was approximately five to eight times and the activity of the desquamatory-related proteases kallikrein 5 and kallikrein 7 approximately two to four times higher on the cheek than on the forearm. There were no gender-related differences in these enzyme activities except for the increased kallikrein 7 in the forearm skin of the female subjects in winter. Reduced kallikrein 5 was associated with increased SC cohesion, as judged by increased protein removal, in forearm skin in the winter months of the year although the skin was clinically normal. It can be concluded that (i) protected skin areas show lower TEWL, skin pH and skin hydration and less protease activities than skin areas that are exposed to the environment, possibly indicating subclinical inflammation on these body sites, (ii) in normal healthy forearm skin, the outer SC exhibits greater serine protease activity than its deeper layers, (iii) compared with the forearm, urokinase- and plasmin-like activities are elevated on SC strippings from the cheek, confirming activation of the plasminogen cascade, and (iv) tryptase-like activity in the SC is also elevated in samples from the cheek, possibly indicating involvement of mast cells in these barrier-compromised body sites or the synthesis of a novel tryptase-like enzyme by keratinocytes. Although elevation of the activities of urokinase, plasmin, kallikrein 5, kallikrein 7 and now a tryptase-like enzyme was observed on SC derived from skin of clinically normal cheeks, we anticipate even higher activities in skin conditions where the epidermal barrier is further impaired.

Nanosystems for skin hydration: a comparative study.

Abstract: Synopsis The present investigation describes a comparative study for the design of innovative topical formulation for skin hydration. In particular, different colloidal forms based on lipidic components have been produced and characterized. Morphology and dimensional distribution have been investigated by means of electron microscopy and photon correlation spectroscopy. Nanoparticulate systems characterized by different morphology and dimensions depending on production procedures have been obtained, namely cubosomes, nanovesicles, solid lipid nanoparticles and liposomes. Hydration power has been studied by means of a corneometer, measuring the skin electrical capacitance before and after the application of opportunely viscosized nanoparticulate systems. It has been demonstrated that nanovesicle gel displayed a pronounced hydration power with respect to the other nanostructured forms, its hydration effect on skin was 3.5-fold higher, with respect to the untreated area, after 5 min from the application and 1.5-fold higher after 2 h. Resume La recherche actuelle decrit une etude comparative pour la conception de la formulation topique innovatrice pour l'humidication de peau. Differentes formes colloidales basees sur les composants lipidiques ont ete produites et en particulier caracterisees. La morphologie et la distribution dimensionnelle ont eteetudiees au moyen de microscopie electronique et spectroscopie de correlation de photon. Des systemes de Nanoparticulate caracterises par la differentes morphologie et dimensions selon des procedures de production ont ete obtenus, a savoir des cubosomes, des nanovesicles, des nanoparticles pleins de lipide et des liposomes. La puissance d'humidication a eteetudiee au moyen d'un corneometer, mesurant la capaciteelectrique de peau avant et apres que l'application d'opportun viscosized des systemes de nanoparticulate. On l'a demontre que le gel de nanovesicle a montre une puissance prononcee d’ humidication en ce qui concerne l'autre nanostructured des formes, son effet d'humidication sur la peau etait 3.5 fois plus haut, en ce qui concerne le secteur non traite, apres 5 minutes de l'application et 1.5 fois plus haut apres 2 heures.

Proposed protocol for determination of photostability Part I: cosmetic UV filters.

Abstract: Le present protocole a ete developpe afin de mesurer la stabilite des filtres UV-B. Une version modifiee est recommandee en ce qui concerne les filtres UV-A. Ce protocole de test doit etre considere comme un instrument servant a la prediction de l'efficacite restante apres exposition a la lumiere. Il s'agit d'un modele in vitro simple et fiable simulant les conditions d'utilisation reelle. Les resultats ont montre que chaque filtre necessite un choix approprie de conditions analytiques optimisees et reproductibles. Bien que les valeurs absolues soient directement influencees par des incertitudes en irradiance (dosimetrie), des mesures comparatives par rapport a un standard connu sont tres fiables.

Global and systematic demonstration for the practical usage of a direct in vivo measurement system to evaluate wrinkles.

Abstract: Synopsis The global and systematic demonstration for the practical usage of a direct three-dimensional in vivo measurement system (PRIMOS) to evaluate wrinkles was investigated. Ten repetitive measurements of the corner of the eye of a subject showed that the coefficient of variation (CV)% value was 7.0% in a typical line-length roughness parameter Ra (the arithmetic mean of roughness), and that the CV% value in a typical surface area roughness parameter Sa was 2.4%. The relationships between the roughness values obtained from the corners of the eye and the age or wrinkle scores of Japanese women aged 10–70 years was examined. The values of several roughness parameters within the evaluation line length or surface area increased with age and showed a good correlation coefficient (r > 0.743). Similar relationships between the wrinkle scores and the values of roughness parameters were observed (r > 0.699). The roughness values were widely distributed even in the same wrinkle score because the measurement areas were limited and the values of skin roughness, including the microreliefs and/or small warts, were included in the calculation. However, changes in roughness values are considerable following treatment with potent active ingredients such as retinoic acid, so that this in vivo evaluation method is sufficient to objectively evaluate wrinkles. We conclude that the direct three-dimensional analysis of wrinkles in vivo should become a popular method to objectively evaluate wrinkles in clinical tests of wrinkle-smoothing ingredients or following cosmetic surgery to provide evidence of quantitative results. Resume Une demonstration globale et systematique pour l'utilisation pratique d'un systeme de mesurage in vivo tridimensionnel direct (PRIMOS) pour evaluer les rides aeteetudiee. Dix mesurages repetitifs de la cornee de l’œil d'un sujet ont montrees que la valeur du % du coefficient de variation etait de 7,0% pour un parametre de rugosite de mesure typique Ra (moyen arithmetique de rugosite), et que la valeur du % du coefficient de derivation pour un parametre de rugosite d'une surface typique Saetait de 2,4%. Les relations entre les valeurs de rugosite obtenues des cornees de l’œil et l’âge ou les indices de rides de femmes japonaises âgees de 10 a 70 ans furent examinees. Les valeurs de plusieurs parametres de rugosite en-deca de la mesure d’evaluation ou de la surface ont augmente avec l’âge et ont presente un bon coefficient de correlation (r > 0,743). Des relations similaires entre des indices de rides et les valeurs de parametres de rugosite furent observees (r > 0,699). Les valeurs de rugosite furent largement reparties meme avec un indice de rugosite semblable, du fait que les zones de mesurages furent limitees et que les valeurs de rugosite de la peau, comprenant des microreliefs et/ou de petites verrues, furent inclues dans les calculs. Cependant, des changements dans les valeurs de rugosite ont ete considerables selon le traitement avec des ingredients actifs potentiels, tel que l'acide retinoique, de telle sorte que cette methode d’evaluation in vivo est suffisante pour une evaluation objective des rides. Nous en concluons qu'une analyse tridimensionnelle directe des rides in vivo est une methode pratique pour evaluer objectivement des rides dans des essais cliniques d'ingredients d'adoucissage des rides ou en suivant une chirurgie esthetique pour mettre en evidence des resultats quantitatifs.

Importance of substrate roughness for in vitro sun protection Assessment

Abstract: The purpose of this study is to demonstrate the influence of plate roughness on well-known absolute or relative UV spectroscopic indices such as the in vitro SPF, in vitro UVA PF (PPD), UVA/UVB ratio, critical wavelength and SPF/UVA PF (PPD) ratio. Firstly, a roughness index was measured by non-contact surface topography analysis on different PMMA plates, which are available today on the European market. A large difference between maximum and minimum plate roughness values could be measured ranging from 1.88 to 6.76 μm. Then, the PMMA plates were grouped into five different roughness classes. To measure the different spectroscopic indices, the same sunscreen preparation was applied at the same amount rate (1 mg cm–2) to each of the selected plates. Large differences were noted for the absolute in vitro indices SPF and UVA PF (PPD), with the SPF varying in one instance from 13.5 to 40.7. On the other hand, the relative absorbance indices UVA/UVB ratio and critical wavelength showed a small but significant variation in relation to roughness. The SPF/UVA PF (PPD) ratio index based on the direct in vitro values was found to be very sensitive to roughness variation. However, adjusting the UV absorbance curve to reach equality between the in vitro SPF and in vivo SPF is a recognized and efficient mathematical process to limit the variation. All these results can be interpreted using the irregular sunscreen film theory. Mathematical developments can be achieved by modelling the height distribution with a gamma function.

Prebiotic Cosmetics: An Alternative to Antibacterial Products

Abstract: The concept of prebiotics is well known from food products, where several ingredients are used to stimulate the beneficial gut microflora. However, prebiotic substances can in principle be applied to balance almost any microbial community to achieve advantageous effects. Since many cosmetic products target skin bacteria as a cause for undesirable conditions like inflammation or body odour, prebiotic actives can help to cope with these problems in a very effective way. To ensure a focused and successful mode of action we demonstrated that it is essential to analyse the microflora and the interactions between different bacterial species carefully. These analyses were made using a molecular method, fluorescence in situ hybridization (FISH), allowing a precise determination of a bacterial community without the drawbacks of classical culture methods. In a further step it was then possible to identify new actives that inhibit harmful or unwanted bacterial species while protecting the beneficial flora. Using a quick and reliable in vitro screening method we found several plant extracts (e.g. Ginseng or Black currant) which inhibit the inflammation-causing bacterium Propionibacterium acnes, but do not affect beneficial species like coagulase-negative staphylococci. In addition, it could also be demonstrated that a prebiotic product line for treatment of inflamed (or acne prone) skin showed the predicted effects on the microflora composition in a first in vivo trial, i.e. decrease of Propionibacterium acnes at a constant level of total bacteria. After 3 weeks, the microflora of 91% of the volunteers had been rebalanced in this way. Furthermore, these formulations have been shown to exhibit excellent skin compatibility compared to an antibacterial product. Thus, prebiotic substances have the potential to provide a gentle and sustainable alternative to undirected antibacterial ingredients which can cause irritation, and frequently only show short time effects. Paper presented at the IFSCC Conference 2005, Florence, Italy.

Protection against singlet oxygen, the main actor of sebum squalene peroxidation during sun exposure, using Commiphora myrrha essential oil.

Abstract: Squalene is a component of sebum. Both are directly exposed to the external environment and play a key role in skin physiology. They are particularly prone to photo oxidation during sun exposure. We studied the impact of two types of antioxidant on sebum squalene peroxidation by UV irradiation. The first type is free radical scavenger (Butyl hydroxyl toluene and an olive extract rich in hydroxytyrosol). The second type is the essential oil of Commipora myrrha, a singlet oxygen quencher. These properties were confirmed using the 2,2-diphenyl-1-picrylhydrazyl test for antiradical capacity [Yoshida et al. (1989) Chem. Pharm. Bull., 37, 1919; Buenger et al. (2006) Int. J. Cosmet. Sci., 28, 135] and 1,3-diphenylisobenzofuran test for the capacity to quench singlet oxygen [Kochewar and Redmond (2000) Meth. Enzymol., 28, 319; Racine and Auffray (2005) Fitoterapia, 76, 316]. Furthermore, we have extended an ex vivo method to classify the efficacy of cosmetics to protect squalene by collecting sebum in vivo and irradiating it in a controlled way. The squalene monohydroperoxide formation is monitored by high performance liquid chromatography. This methods allows us to compare the efficiency of the three antioxidants at 0.6% in a cosmetic formulation to protect squalene from photo oxidation. Our results clearly show that essential oil of Commiphora myrrha provides the best protection against squalene peroxidation. These results demonstrate that squalene peroxidation during solar exposure is mainly because of singlet oxygen and not due to free radical attack. This suggests that sun care cosmetics should make use not only of free radical scavengers but also of singlet oxygen quenchers.

Preliminary studies towards utilization of various plant extracts as antisolar agents.

Abstract: Synopsis The aim of this work was to evaluate several plant extracts with regard to ultraviolet absorption spectra in view of a possible application as antisolar agents. Liquid and dry extracts of Hamamelis virginiana, Matricaria recutita, Aesculus hippocastanum, Rhamnus purshiana and Cinnamomum zeylanicum were prepared by repercolation, maceration and microwave oven extraction. UVB absorption spectra (290-320nm) were obtained and the solar protection factors (SPF) of these preparations were determined by a spectrophotometric method. The results showed that after incorporation to a 2% solution of the synthetic sunscreen octylmethoxycinnamate, the extracts showed an intensification in SPF values, suggesting that this can be an interesting method to intensify SPF. In addition, these extracts can contribute their emollient and moistening properties to the product. These are important characteristics for protecting skin against exposure to the sun.

In vitro skin permeation and retention of parabens from cosmetic formulations.

Abstract: Parabens are antimicrobial agents widely used in foods, cosmetics and pharmaceutical products. Although non-mutagenic, non-teratogenic and non-carcinogenic, parabens can induce allergic contact dermatitis and posses estrogenic activity. The aim of this work was to assess the skin permeation and retention of methyl- (MP), ethyl- (EP) and propyl- (PP) paraben from three commercial cosmetic creams. The results obtained indicate that parabens are capable of permeating through and accumulating in the skin. The extent of penetration depends more on paraben characteristics (solubility, lipophilicity) than on the composition of the formulation. In particular, the percentage permeated across the skin was independent of the composition of the cream used and decreased in the order MP, EP and PP, in accordance with decreasing solubility. After 8 h of contact with the skin, 60% of MP, 40% of EP and 20% of PP were found across the skin. Concerning skin retention, the percentage remaining in the skin after 8 h depends on both paraben characteristics and on the composition of the formulation used. In conclusion, it appears that only the type of paraben, in particular its water solubility, affects skin penetration whereas the composition of the emulsion, which influences skin retention, plays a secondary role. Finally, excised rabbit ear skin can be considered as a good model for human skin for in vitro experiments.

Emulsifying power of mannan and glucomannan produced by yeasts

Abstract: Synopsis Subject of study was the colloid chemical properties of the biopolymers mannan, synthesized from strain Rhodotorula acheniorum MC, and glucomannan, synthesized from strain Sporobolomyces salmonicolor AL1. Their emulsifying capacity was studied in model systems of aqueous solutions in concentrations from 0.5% to 2.5% with regard to the aqueous phase. Emulsions of the direct type (oil/water) with 50% oil content were obtained. A disperse system with 2.5% glucomannan had 100% intact emulsion in the centrifugation test, while for the system with mannan, this indicator was 72%. Lab cream emulsions were obtained with glucomannan and with the emulsifiers Rofetan N/NS and Arlacel 165 used in the cosmetics industry. It has been established that under standard testing conditions, cream-like emulsions with 2.0% glucomannan have stability indicators comparable to these of 5.0% rofetan N/NS and 5.0% Arlacel 165. The samples with different concentrations of glucomannan showed a pseudo-plastic behaviour, as the highest viscosity was shown by the emulsion with 2.0% stored at 45°C. The newly synthesized exopolysaccharides had a distinct emulsifying power and can be applied in the cosmetic and food industries. Resume L'objet de ce travail a ete d’etudier les proprietes colloidales des biopolymeres de type mannane, synthetises a partir de la souche Rhodotorulla acheniorum MC et de type glucomanane, synthetises a partir de la souche Sporobolomyces salmonicolor AL1. Leurs performances emulsifiantes ont eteetudiees dans des systemes modeles aqueux a des concentrations en polymeres compris ente 0.5 et 2% en fonction de la phase aqueuse. Des emulsions directe (H/E) avec 50% d'huile ont ete obtenues. Un systeme disperse contenant 2.5% de glucomanane a montre 100% d’emulsion intacte dans le test de centrifugation, alors que dans le meme test le systeme contenant le mannane ne montrait que 72% d’emulsion intacte. Des emulsions cremes ont ete obtenues avec le gluconannane et avec les emulsifiants Rofetan N/NS et Arlacel 165 utilises par l'industrie cosmetique. Il a eteetabli que dans des conditions de tests standard, les emulsions cremes avec 2% de glucomannane possedent un indice de stabilite comparable a celles contenant 5% de Rofetan N/NS et 5% d'Arlacel 165. Les echantillons avec des concentrations differentes de glucomannane ont montre un comportement pseudo plastique, l’emulsion avec 2.0% conservee a 45°C possede la viscosite la plus importante. Les exo polysaccharides nouvellement synthetises possedent des proprietes emulsionnantes certaines et peuvent trouver une application dans les industries cosmetiques et alimentaires.

Influence of a pretreatment with emulsions on the dehydration of the skin by surfactants

Abstract: Improving the water content of the horny layer of the skin is of great importance in dermatology (atopic dermatitis, ichthyosis etc.) and in cosmetics (to soften the skin surface [l]). It is believed that emulsion bases lead to hydration of the stratum corneum [2]. The hydration is believed to last a few minutes if an o/w-emulsion is used [3] and a few hours in the case of w/o-emulsions [4]. The present study addresses whether the hydrating effect really does last for such a short time. Literature also proposes an increase in water content by using urea, which is a component of many dermatological skin-care ointments [3,5-8]. The cosmetic industry mostly prefers glycerol of which a hydrating effect is also assumed [9], although it is not well documented. Our study compares in a quantitative way the hydrating effect of urea and glycerol applied in different types of emulsions. In practice the dehydration caused by surfactants is a major problem for people with ‘dry’ skin. As far as we know there are no adequate studies about the influence of skin-care products with or without moisturizers like urea or glycerol. The purpose of our study was to compare the protective effect of w/oand o/w-emulsions with and without urea or glycerol against exsiccation caused by surfactants.

Salicyloyl‐phytosphingosine: a novel agent for the repair of photoaged skin

Abstract: In recent years the importance of sphingolipids (cerebrosides, sphingomyelin, ceramides, sphingosine-1-phospate, etc.) in skin biology is receiving an increasing interest. Not only are ceramides essential for the barrier function of the skin, especially through their phytosphingosine, sphingosine and 6-hydroxysphingosine derivatives, they are now also known to be cell-signalling mediators which can improve epidermal differentiation. However, their effects on dermal anti-ageing markers and reduction of wrinkles have not been established. In this study, we were interested in the effects of a sphingolipid derivative, salicyloyl-phytosphingosine (SP), because of the known independent beneficial effects of salicylic acid and phytosphingosine on skin. Both of these agents are known to reduce the activities of the activator protein-1 transcription factor, in a manner similar to that observed with retinoic acid (RA) treatment. Through this mechanism, RA was shown to reduce the levels of matrix metalloproteases (MMPs) and the increase levels of extracellular matrix proteins. Therefore, we examined the effects of SP on procollagen-I synthesis in fibroblasts in vitro, its effects in vivo on the expression of dermal markers such as fibrillin-1, procollagen-I and MMP-1 immunochemically in biopsies taken from a short-term occluded patch test protocol and, its effects on periorbital wrinkle reduction over 4 weeks using Fast Optical In Vivo Topometry of Human Skin. In vitro we observed a significant increase in the production of procollagen-I by adult human fibroblasts (two fold increase, P < 0.01) which encouraged us to test the effects of SP in vivo. Initially, test products (SP at 0.05% and 0.2%, all-trans RA (0.025%) and vehicle were applied under occlusion for 8 days prior to biopsy and histological assessment in photoaged volunteers (n = 5). Increased deposition of fibrillin-1 and procollagen-I, together with reductions in the levels of MMP-1, were observed for the SP treatments (P < 0.05). Similar effects were observed for RA, except for the increases in procollagen-I. With these beneficial effects on the basement membrane and papillary dermal markers, we evaluated the effects of SP in an oil-in-water (O/W) cream for its effects in reducing the appearance of periorbital wrinkles in a 4-week, half-face clinical study compared to placebo cream (moderately photoaged female subjects aged 41-69 years; n = 30). Clear reductions in wrinkle depth and Rz (skin smoothness) together with Ra (skin roughness) parameters were observed (P < 0.05), indicating an anti-wrinkle benefit. In conclusion, this series of studies demonstrated for the first time that a ceramide derivative, such as that SP, was a novel agent for the repair of photoaged skin and highlight its effects at the cellular, tissue and organ levels.

High-performance liquid chromatographic determination of arbutin in skin-whitening creams and medicinal plant extracts.

Abstract: A high-performance liquid chromatographic method was developed for quantitative analysis of arbutin. The arbutin was separated on an ODS Hypersil C(18) column with a mobile phase of water:methanol:0.1 M hydrochloric acid (89:10:1, v/v/v). The level of arbutin was measured by means of UV detection at 222 nm. The optimum conditions for arbutin quantitative analysis were investigated. The calibration curve was found to be linear up to 1,000 microg/ml(-1) of arbutin concentration, and the working calibration curve for arbutin determination over the range 0.5-30.0 microg/ml(-1) of arbutin (r(2)=0.9999) was established. The relative standard deviations for intraday and interday were found to be 0.98% and 1.15%, respectively. A detection limit (3sigma) and quantitation limit (10sigma) of 0.02 microg/ml(-1) and 0.2 microg/ml(-1), respectively, and a mean percentage recovery of the spiked arbutin of 99.88 +/- 1.12% were obtained. The proposed method has been applied to the determination of arbutin in commercial skin-whitening creams (Arbuwhite cream, Super Whitening cream, and Shiseido cream) with average contents of 7.60, 5.30, and 57.90 mg/g(-1), respectively. It was also applied to the determination of arbutin in medicinal plant extracts from Betula alnoides Buch. Ham., Clerodendrum petasites S. Moore, Curculigo latifolia Dryand. Var. latifolia, and Hesperethusa crenulata (Roxb.) Roem, levels of which were found to be 3.50, 1.50, 1.10, and 0.12 microg/g(-1), respectively (no article reported in the literature about arbutin analysis). The proposed HPLC method is rapid, simple, and selective for routine analysis.

Increasing quality of life by improving the quality of skin in patients with atopic dermatitis

Abstract: Synopsis Atopic dermatitis is a chronic relapsing inflammatory skin disease which usually starts during the first years of life. In patients with the disease, the quality of skin is severely affected, and this is closely linked to a reduced quality of life. An increas

Equilibrium water sorption characteristics of the human nail

Abstract: The physical and transport properties of keratinized tissues are closely related to their water content. This report presents water uptake and desorption isotherms for the human nail and compares them with those of wool, horn, hair, and stratum corneum. Nail absorbed a maximum of approximately 0.3 g H(2)O/g dry tissue, with the shape and magnitude of the isotherm most closely resembling horn. Hysteresis between uptake and desorption was observed, similar to that of other keratins. The shape of the isotherms was adequately described by both the D'Arcy-Watt and Guggenheim-Anderson-deBoer (GAB) models; however, small positive deviations from both models were found in the relative humidity range, 30-60%. Directionally better fits to the data were found with the D'Arcy-Watt model. This analysis suggests that most of the water in the tissue was in a strongly bound state, consistent with observations made by other techniques.

Influence of PEG‐12 Dimethicone addition on stability and formation of emulsions containing liquid crystal

Abstract: Oil/water emulsions, containing liquid crystals, were developed employing Andiroba oil, PEG-12 Dimethicone and Crodafos CES. It was evaluated the influence of silicone surfactants on the emulsions stability and on the formation of liquid crystalline phases and therefore, physicochemical characteristics, such as rheology and zeta potential, were evaluated. Emulsions were prepared by the emulsions phase inversion method. All the formulations presented lamellar liquid crystalline phases. The PEG-12 Dimethicone addition did not change microscopically the liquid crystalline phases. The emulsions containing silicone demonstrated lower viscosity than those without the additive. This is an important feature, as the silicone did not change the rheological profile; however, the addition of silicone still can be used as a viscosity controller. The formulations had their viscosity increased 15 and 150 days after their preparation. This characteristic shows that the emulsions have their organization increased along the storing time. In the analysis of zeta potential, we could verify that all formulations presented negative values between -39.7 and -70.0 mV. Within this range of values, the emulsion physical stability is high (Fig. 10). It was concluded that the addition of PEG-12 Dimethicone kept the liquid crystalline phase of the emulsion obtained with Crodafos CES, influencing in a positive way in the system stability.

Effect of fluid intake on skin physiology : distinct differences between drinking mineral water and tap water

Abstract: It is generally stated that drinking plenty of water has a positive influence on skin condition. However, there is no published scientific study that has investigated this matter. The aim of our exploratory 'before-after' study was to evaluate the in vivo influence of drinking more than 2 L of mineral water or ordinary tap water per day on skin physiology. Ninety-three healthy subjects were included in our prospective study. After an initial run-in phase of 2 weeks to monitor individual drinking habits, subjects had to drink 2.25 L day(-1) of either mineral water (n = 53) or tap water (n = 40) for 4 weeks. Bioengineering in vivo measurements on the volar forearm included sonographic evaluation of skin thickness and density, determination of skin surface pH, assessment of skin surface morphology, and measurement of finger circumference. Eighty-six subjects completed the study. In the mineral water group measurements revealed a statistically significant decrease in skin density. Skin thickness increased slightly, albeit not at a statistically significant level. However, when separately analysing those individuals from the mineral water group, who had routinely drunken comparably little before the start of the study, their skin thickness increased at a statistically significant level. Skin surface pH remained almost unchanged in the physiologically optimal range. In the tap water group, skin density increased significantly, while skin thickness decreased significantly. Skin surface pH decreased at a statistically significant level. While in the mineral water group finger circumference decreased significantly, measurements in the tap water group revealed a statistically significant increase. Objective skin surface morphology did not change in any group. In summary, drinking more than 2 L of water per day can have a significant impact on skin physiology. The exact effects within the skin seem to differ depending on the nature of the water ingested. Randomized, controlled, double-blind follow-up trials are warranted to confirm the findings of our exploratory pilot study.

Calculation of optimum emulsifier mixtures for phase inversion emulsification

Abstract: Synopsis The phase inversion emulsification is a convenient method of preparing fine-disperse and long-term stable oil-in-water emulsions, which are stabilized with nonionic emulsifiers. On the basis of EACN-values (equivalent alkane carbon numbers) the calculation of phase inversion in concentrates (CAPICO) is possible, which yields emulsifier and oil mixing ratios corresponding to a given phase inversion temperature (PIT). The CAPICO-method is illustrated for the example of a cosmetic oil-in-water lotion containing an oil mixture, glyceryl monostearate and a fatty alcohol ethoxylate. Of special interest is the influence of silicone oils on the PIT. At a constant emulsifier oil ratio the complete phase behaviour of this emulsion system is represented in a temperature/water content graph. Optimum emulsification results are obtained if during PIT emulsification a microemulsion or a lamellar phase is passed. The emulsions were characterized by particle sizing, and emulsion stability against sedimentation was evaluated by ultrasonic velocity changes. A fine-disperse and long-term stable oil-in-water emulsion was prepared by a time and energy-saving two-step hot-cold process.

Impact of shaving and anti-perspirant use on the axillary vault.

Abstract: Shaving the axilla is a regular part of the personal care regime for many women in Europe, North and South America. To assess the impact of shaving on underarm skin, a series of investigations were carried out, in which the thickness of the axillary vault and fossa were measured using optical coherence tomography (OCT), and underarm shaving debris was collected for study. The response of the axilla to histamine iontophoresis was also investigated. Additionally, a study was carried out to investigate the impact of a novel anti-perspirant roll-on formulation on irritation and self-perceived sensory properties of the axilla. The results clearly demonstrate that shaving the underarm consistently removes skin (stratum corneum) as well as axillary hair (with a mean value of 36.1% of the debris being skin). OCT measurements demonstrated that in shaved areas of the axilla, epidermal thickness is higher than in unshaved areas. In response to histamine, wheal and flare were both found to be greater in the shaved axilla, when compared with an unshaved control, but flare in the fossa was greater than that in the vault. On the basis of these results, we propose that the axillary vault has adapted to frequent shaving, notably by the development of a thickened epidermis. However, this adaptation is often not sufficient to fully protect the axilla from damage and irritation resulting from hair removal (shaving). In these instances, we have demonstrated that use of a novel anti-perspirant roll-on formulation containing glycerol and sunflower seed oil was able to reduce the impact of shaving-induced irritation and improve self-assessment of axillary condition.

Nanostructure of the stratum corneum extracellular lipid matrix as observed by cryo-electron microscopy of vitreous skin sections

Abstract: In recent years, high-resolution cryo-electron microscopy of vitreous skin sections has been used to visualize the formation and structure of the human stratum corneum extracellular lipid matrix. The aim of the present work was to summarize these findings. It is proposed that skin barrier formation does not take place as a 'lamellar body' fusion process, but as a lamellar 'unfolding' of a small lattice parameter lipid 'phase' with cubic-like symmetry with subsequent 'crystallization' and concomitant lamellar re-organization of the extracellular lipid matrix.

Sunless tanning products containing dihydroxyacetone in combination with a perfluoropolyether phosphate

Abstract: It is well known that the shelf-life of products containing dihydroxyacetone (DHA) is quite unsatisfactory, and that in this area the adjustment to an acidic pH is the way usually recommended to improve DHA stability. The adoption of this rule, however, is a challenge for the cosmetic chemist not only because of the risks of skin irritation, but also because of the strong limitations in the choice of the acidic agent. It occurs that the use of either hydroxy-acids and phosphoric acid/phosphate buffers has the opposite effect on the one intended. Recently, a perfluoropolyether phosphate (PFPE phosphate) was introduced as a new acidic agent to lower the pH without increasing the skin irritation. Starting from a rationale based on this potential, we investigated sunless tanners containing PFPE phosphate and DHA. We monitored the ageing of sunless tanners with and without PFPE phosphate, by visual observation and instrumentation (pH measures and (1)H-NMR spectroscopy). Furthermore, to evaluate whether the substances produced from the DHA degradation are potential irritants, patch tests on volunteers were used to check the safety and indirectly the stability of the compositions. In conclusion, our investigations on the guidelines to formulate DHA-containing sunless tanners: confirmed that the pH is a key parameter in formulating these compositions; proved that PFPE phosphate is a safe and compatible ingredient to lower the pH; gave some evidence of the critical importance of thickeners; suggested a strategy based on multifunctional agents to minimize the ingredients.

Pores in the epidermis: aquaporins and tight junctions

Abstract: Water homeostasis of the epidermis is important for the appearance and physical properties of the skin, as well as for water balance in the body. It depends on several factors, e.g. barrier quality, uptake of water into the epidermis, concentration of water-retaining humectants, and external humidity. Aquaporins (AQPs) are pores in the plasmamembranes of cells. Monomeric AQPs form barrel-like structures that are primarily water selective, some AQPs also transport glycerol and possibly other small solutes. In the epidermis, AQP3 is the predominant AQP. It is localized mainly in basal but also in suprabasal layers of the epidermis and is permeable for water as well as for glycerol, a humectant. Mice deficient in AQP3 exhibit reduced stratum corneum (SC) hydration and impaired SC barrier recovery after SC removal. In skin diseases associated with elevated transepidermal water loss (TEWL) and reduced SC hydration, altered expression of AQP3 was shown. Tight junctions (TJ) are cell-cell junctions, which play a central role in sealing the intercellular space of cell sheets and thereby establishing a paracellular barrier. Within the TJ, pores are postulated to exist, which allow the controlled diffusion of water and solutes via the paracellular pathway. In the epidermis, TJ structures were demonstrated in the stratum granulosum whereas TJ proteins were found in all viable layers. Mice which overexpress or are deficient of key-proteins of TJ die soon after birth because of a tremendous TEWL. In various skin diseases that are accompanied by elevated TEWL and reduced skin hydration, staining patterns of TJ proteins are altered. This review will summarize our current knowledge of the involvement of AQPs and TJ in the water homeostasis of the epidermis.

Interaction of mixture of anionic surfactants with collagen

Abstract: Study focused on interaction of collagen fibres of collagen I with anionic surfactants sodium dodecylbenzene sulphonate (SDBS), sodium dodecyl sulphate (SDS) and their mixtures at pH = 6, at two ionic strengths (I = 0.06 mol L(-1) and I = 0.4 mol L(-1)) and laboratory temperature. Surfactants and their mixtures were characterised by their critical micelle concentration (c.m.c.), composition of mixed micelles and interaction factor beta according to Rubingh. Dependency of c.m.c. on mixture composition has an opposite tendency at both ionic strengths, which proves the greater influence of added electrolyte on behaviour of SDS than of SDBS. Interaction was evaluated by means of binding isotherms and mass swelling degree alpha(m). The bound quantity partly depends on mixture composition, partly on ionic strength. SDS and mixtures containing its greater quantities are bound more than SDBS (approx. 150% related to SDBS). Increased ionic strength of the environment increases bound quantity in approximately same manner, heedless of adsorbate composition. Even composition of the mixture after interaction with fibres does not markedly alter from initial composition. Fibre swelling is affected by composition of swelling mixture similarly to binding - it increases with growing quantity of surfactants. Greater ionic strength acts against collagen swelling, and at given ionic strength (I = 0.4 mol L(-1)) swelling attains half values compare to swelling at low ionic strength (I = 0.06 mol L(-1)). There are characteristic concentrations of both surfactants and their mixtures (c(s) approximately 0.5 - 1.0 mmol L(-1)) that do not produce swelling. It is assumed that this range of concentrations corresponds to amount of surfactants bound to collagen through electrostatic forces and thus to temporary increase in fibre hydrophobity.

In vitro assessment of water resistance of sun care products: a reproducible and optimized in vitro test method

Abstract: Synopsis The aim of the study was to develop a simple reproducible and reliable in vitro water resistance (WR) method to assess the sun care products. This paper is the result of a scientific collaboration between seven different international industrial laboratories and testing institutes. The same group has already achieved an in vitro protocol for the sun protection factor (SPF) determination [1]. The in vitro WR of sunscreens was tested by applying the same principle as in vivo, which determines the percentage of retention of sunscreen products by assessing the SPF before and after water immersion. Special care was taken to study the parameters influencing the WR and the possibility to follow the kinetics of sunscreen retention during water immersion. The influence of different water qualities has been tested, and osmosed water (1–3 μS cm–1) was chosen for the main ring study. Measurement was carried out after 5, 20 and 40 min of immersion. Histograms of selected products demonstrate the percentage of WR at all measuring times and centres, and the regression coefficient to the in vivo determination was shown and statistical calculations clearly demonstrate the reproducibility of the results between the different evaluation centres. The presented method is a practical, convenient and relevant tool for WR screening of sun care and skin care products. It even has the potential to be the starting point for the replacement of the in vivo method in future.