Evaluation of the irritant capacity of decyl polyglucoside

Synopsis
The irritant capacity of several anionic, amphoteric and non-ionic surfactants has been studied by non-invasive techniques, specifically by evaporimetry, laser Doppler flowmetry and one-dimensional cutaneous ecography. Some of the surfactants most frequently used in shampoos and shower/foam gels were selected for testing. A series of aqueous solutions containing 5% of the active material in these products was patched onto normal skin; controls for comparison were set up with water and with sodium lauryl sulphate (SLS), a recognized irritant standard substance.
It was deduced from the results obtained that, of the surfactants tested, the one showing the lowest irritant capacity is decyl polyglucoside, followed in increasing order of irritant capacity, by cocoamidopropyl betaine, magnesium laurylether sulphate and sodium laurylether sulphate.
Résumé
La capacitée irritante des beaucoups des tensioactives anioniques, anfoteric et no-ioniques on étéétudiées avec métodes no invasives, particulierment avec évaporimetrie, laser DOPPLER et écografie cutanée unidimensionel. On á selectionné pour son texture quelques tensioactives utilisée plus frequement en shampooing et gel de bains ou douche.
On á formulé une series des solutions ocuoses en contenent un 5% des matieres actives quón á emplâtre en peaux normaux, on áétablie des contrôles des comparations avec de l'eau et sodium lauryl sulphate (SLH) une substancie de reconnue irritabilitée.
Des resultats obtenue on á deduit que tous les tensioactives quón á textés, celui qui á montré le meneur capacité irritant il fut decyl polyglucoside, suivi en ordre montante de capacité irritant por cocamidopropyl betaine, magnesium laureth sulphate et sodium laureth sulphate.     

The influence of alkane chain length on the skin irritation potential of 1,2-alkanediols

Several studies have reported that 1,2-alkanediols show increasing anti-microbial activity as their alkane chain length increases. However, there are no reports on the influence of alkane chain length on the skin irritation potential of 1,2-alkanediols. To investigate the influence of alkane chain length on the skin irritation potential of 1,2-alkanediols. The objective and subjective (sensory) skin irritation potentials of five 1,2-alkanediols - 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol, 1,2-octanediol and 1,2-decanediol - were evaluated. We also estimated percutaneous absorption by measuring in vitro skin penetration using a Franz diffusion cell system. Like anti-microbial activity, sensory irritation potential increased as alkane chain length increased, most likely due to increasing membrane interference and/or intrinsic toxicity of 1,2-alkanediols. 1,2-Hexanediol showed the lowest objective skin irritation potential, which increased when the alkane chain length decreased or increased. Furthermore, percutaneous absorption negatively correlated with the alkane chain length of 1,2-alkanediols. These results show that a lower skin absorption potential is not indicative of a low skin irritation potential. Our results suggest that the factors and processes involved in skin irritation potential are complex and that skin irritation potential is influenced by intrinsic toxicity and the potential for penetration or integration in the lipid bilayer.     

The physico-chemical properties and protein denaturation potential of surfactant mixtures

Protein denaturation was investigated to establish an in vitro evaluation method of surfactants in connection with their in vivo irritation potency to human skin. Eventually a new method with simplicity and high reproducibility was established by using quantitative analysis with gel-permeation chromatography (GPC). The protein denaturing potency of the commercially available surfactants was measured by using the developed method. Synergistic reduction in protein denaturation was observed in the mixed systems of anionic and amphoteric surfactants. The synergistic reduction was explained in terms of the physico-chemical properties of the mixed surfactants. A possible mechanism is the remarkable lowering of the total monomer concentration by the formation of hydrophobic complexes between the anionic and amphoteric surfactants.
Relation entre les propriétés physico-chimiques des mélanges de surfactifs et leur potentiel de dénaturation des protéines     

发用类、肤用清洁类化妆品的急性皮肤和眼刺激损害特点

分析发用类、肤用清洁类化妆品的急性皮肤刺激和急性眼刺激损害特点,了解其卫生安全状况。于2012年采用《化妆品卫生规范》(2007年版)中的急性皮肤刺激性实验和急性眼刺激性实验对发用类、肤用清洁类共计158种化妆品样品进行测试。两类受试化妆品显示出不同程度的急性皮肤刺激性和急性眼刺激性损害效应。发用类化妆品在实验中基本无皮肤刺激性损伤;肤用清洁类化妆品在实验中有少量的皮肤刺激性损伤,但大都为轻刺激性(31.0%),只有个别(3.8%)出现了皮肤红斑水肿的中刺激性损伤。发用类、肤用清洁类化妆品在急性眼刺激性实验中检出一定比例具有微刺激性及以上刺激性的样品,但引起的眼损伤都能够在观察期限内恢复。本次调查的所有化妆品中,洁面类、洗发类化妆品普遍具有急性眼刺激性和急性皮肤刺激性损害,需加强对化妆品的监督管理,进一步提升化妆品卫生安全水平,保障化妆品使用安全。     

The effect of a synthetic ceramide-2 on transepidermal water loss after stripping or sodium lauryl sulfate treatment: an in vivo study

The integrity of the chemical and physical structure of the horny layer is essential for maintaining the skin in good health. Any disturbance of this integrity may lead to cutaneous reactions of varying degree: dryness, redness, inflammation. The measurement of Transepidermal Water Loss (TEWL) allows one to record this kind of disturbance and to follow the slow return to normal. In this in vivo study two techniques of insulting the epidermis were used: stripping and washing with sodium lauryl sulfate (SLS). A significant increase of TEWL values resulted in both cases. The application of emulsions containing 0.5% and 1% of a synthetic ceramide type-2 (N-stearoyl-DL-erythro-sphinganine) decreased the disturbance measured by TEWL, in a significant fashion in both trials. The placebo emulsions showed no significant effect. The ceramide thus seemed to participate in the restructuring of the horny layer.     

New protein ingredients for skin detergency: native wheat protein–surfactant complexes

The cutaneous tolerability of detergent formulations can be improved by means of suitable additives. Exogenous proteins, for example, are able to reduce the skin irritation potential of surfactants according to a double mechanism: they complex the surfactant molecules lowering the concentration of their free monomeric species; they link to the skin keratin forming a protective colloidal layer that shields the denaturing attack of surfactants. Protein derivatives used as additives for detergency are usually prepared by partial hydrolysis of animal scleroproteins or plant reserve proteins. The main purpose of the hydrolytic cleavage is to make them water soluble and suitable for liquid products. Native, non hydrolysed wheat proteins have been recently introduced as active ingredients for detergents. Water solubility and stability are obtained by means of complexation with surfactants which also increases their actual hydrophobicity, an important parameter affecting cosmetic properties of proteins. The anti-irritant properties of these new derivatives of detergents have been evaluated by in vitro predictive tests (swelling response of collagen membranes), by acute irritancy in vivo methods (occlusive patch tests) and by use tests (forearm washing test). Transepidermal water loss and electric capacitance have been adopted as investigation techniques to evaluate the skin integrity/damage after the in vivo tests. The performance of native wheat protein-surfactant complexes has been compared with traditional protein hydrolysates and to amphoteric surfactants as detergent additives. The results show a noticeable reduction of skin irritation in surfactant formulations with addition of native wheat proteins.     

Studies of perfume solubilisation

The solubilisation of three perfumes has been studied in monoethanolamine lauryl sulphate and sodium lauryl ether sulphate solutions. The effect of the addition of nonionic surfactants have also been followed. A method is described for the olfactive examination of the solutions and results are given for its application to certain of the systems.     

Skin irritancy testing of toiletries and cosmetics on novel human models

A brief review of new techniques of assessing skin irritancy is presented. Some of the difficulties of assessing minor degrees of irritancy are discussed. Nouvelles méthodes pour l'évaluation sur l'être humain du pouvoir irritant des produits cosmetiques at d'hygiene     

纳米银整理抗菌织物耐洗性及皮肤刺激性的评价

为考察抗菌织物的耐洗性及皮肤刺激性,以经纳米银整理的抗菌丝织物为实验对象,采用琼脂平皿扩散法和吸收法对其抗菌性能进行定性和定量实验,采用电感耦合等离子体质谱仪(ICP-MS)测定样品的金属溶出量,同时利用EPI-MODEL人体皮肤模型,对织物水萃取液的皮肤刺激性进行初步研究。结果显示:在洗涤50次后,样品对大肠杆菌8099和金黄色葡萄球菌ATCC6538的抗菌率依然在99%以上,具有良好的耐洗性能;织物水萃取液对皮肤无刺激性,较为安全。     

Prediction and measurement of surfactant action upon human skin under realistic conditions

The lysosomal enzyme acid phosphatase has been characterized and quantified in tapestrip biopsies of human stratum corneum by means of a sensitive spectrofluorometric procedure. When the stratum corneum of panellists was exposed to dilute solutions of various surfactants under realistic exposure conditions, the changes observed in stratum corneum acid phosphatase specific activity have been found to correlate very closely with the visual, macroscopic changes such as dryness and flakiness, that are elicited in skin as a result of surfactants. This method monitors denaturation of stratum corneum proteins, which is an important feature of skin surfactant interactions, and serves as an effective, non-invasive predictive tool for skin irritancy and mildness of surfactants.
Prevention et mesure de l'action des tensio-actifs sur la peau humaine dans des conditions conformes a la réalité     

The inhibitory effect of some amphoteric surfactants on the irritation potential of alkylsulphates

The physico-chemical and biological properties of an amphoteric/anionic system and its behaviour against a proteinic support have been thoroughly investigated. A considerable inhibition of adsorption of SLS (sodium lauryl sulphate) on human callus caused by the presence of definite amounts of AABet (alkyl-amido-betaines) in the treatment bath is observed. These physico-chemical results are in agreement with those obtained by some in vivo biological tests. A mechanism of the process via the formation of mixed micelles is postulated emphasizing the stability of such systems as a function of pH, the influence of the chain length of the amphoteric surfactant and the molar relative ratio SLS/AABet. Consequently, our work offers the possibility of a wide applicability of the synergic mixtures of both types of surfactants to inhibit considerably skin irritation of cosmetic finished products.     

Evaluation of predictable irritative power of surfactant mixtures by human fibroblast culture and its correlation to physico-chemical parameters

The predictable toxic effects of some surfactants, their blends and some preserving agents on human fibroblast cultures were investigated with in vitro tests, with the aim of finding a possible correlation between the biologic evaluations and some physical characteristics of detergent solutions. Lactate dehydrogenase release into the medium was used as a marker of the plasma membrane integrity, while the amount of ³H-radiolabelled proteins in the fibroblasts was measured in order to assess the cell biosynthetic machinery function. Disodium-alkyl-semi-sulphosuccinate induced membrane damage in the lactate dehydrogenase test and decreased the protein synthesis, with an EC 50 around 1mm , while sodium lauryl ether sulphate had an EC 50 at about 100 μm , indicating that this compound is ten-fold more toxic, when measured by this method. An ethoxylated glyceride, on the contrary, was completely harmless on the plasma membrane and, surprisingly, activated fibroblast protein synthesis in a dose-response way up to two-fold. Mixtures of the three surfactants evidenced the protective effect of the non-ionic against the cellular functionality damage. Parabens do not influence this type of evaluation, while some influence was shown by the formaldehyde releaser 2-bromo-2-nitro-propandiol at the highest concentration. The comparison between critical micellar concentration measures of the different surfactants and their in vitro detected irritative power shows, for the two anionics, that in vitro toxicity is proportionally bound to the amount of micelles even if the structural differences between the two types of molecules are reflected into different damage values, while the non-ionic compound shows a not defined CMC and a very low toxicity profile. Blends of anionics with the non-ionic show an increased CMC and a reduced toxicity profile. Toxicity evaluations of complex finished foaming formulations, carried out with human fibroblast cultures evaluation show that a relationship between micelles amount and cell toxicity seems to exist, mainly when multiple surfactants blends are tested.     

The influence of a cream containing 20% glycerin and its vehicle on skin barrier properties

Glycerin is widely used in cosmetics and well as in pharmaceutical formulations, mainly as humectant. In vitro studies have shown glycerin to prevent crystallization of stratum corneum model lipid mixture at low room humidity. Whether this may affect the skin barrier function during repeated application of glycerin in a cream base to normal skin is not known. Therefore, the influence of a cream containing 20% glycerin was compared with its placebo cream in a bilateral, double-blind study on 17 healthy volunteers. The effect was evaluated as influence on hydration with a corneometer and on skin barrier function. Skin barrier function was assessed as permeability to water with an evaporimeter (transepidermal water loss; TEWL) and as sensitivity to an irritating surfactant by measuring the biological response (measured as TEWL and skin blood flow). Ten days treatment of normal skin with 20% glycerin significantly increased skin corneometer values, indicating an increased hydration. However, our study failed to show an influence of glycerin on human skin, in terms of TEWL and skin sensitivity to SLS-induced irritation.     

Irritancy ranking of 31 cleansers in the Indian market in a 24-h patch test

Cleansing trends promise freshness, sensory and health benefits but may also be accompanied by an increase in soap-induced skin irritation. The aim of this study was to evaluate the irritant effect of 31 cleansers (28 bar soaps and 3 liquid cleansers) available in the Indian market. Eight percent w/v solutions of the soaps/cleansers were made and 30 microL of each of the solutions were applied to Finn chambers and occluded for 24 h along with distilled water (negative control) and 20% sodium dodecyl sulphate (SDS) as positive control. The sites were graded for erythema and scaling 30 min after removing the patches. The pH of each of the soap solutions was determined. Mean with SD and ANOVA (F-value) was computed separately for each soap/cleanser with respect to the two parameters, erythema and scaling. The total of the means for both the parameters, erythema and scaling was also computed. The cleansers were listed based on this total from the least irritant to the most irritant. The differences between soaps (F-value) was significant for erythema and scaling [erythema = 4.106 (P = 0.000); scaling = 6.006 (P = 0.000)]. Cetaphil cleansing lotion had the lowest erythema score of 0.25. Lowest scaling score of zero was recorded for Cetaphil cleansing lotion and Elovera moisturizing body wash. Aquasoft and Lifebuoy soaps had the highest erythema score of 2.13. Acnex had the highest scaling score of 1.75; Aquasoft, Hamam scrub bath soap and Naturepower sandal soaps were the next with a scaling score of 1.63. Cetaphil cleansing lotion, Aquaderm liquid soap, Dove bar soap and Elovera moisturizing body wash proved to be the least irritant cleansers with a total score of less than 1. The four most irritant soaps/cleansers had an average score of 3.65. The irritant potential of the majority of the cleansers fell between these extremes. The pH of all the soap/cleanser solutions was neutral to alkaline (pH 7-9) except that of Dove bar, Cetaphil cleansing lotion, Aquaderm liquid soap and Elovera moisturizing body wash which tested acidic (pH 5-6). The pH of the positive control--20% SDS, was acidic (pH 6). The difference in the irritancy potential between soaps/cleansers as determined by the 24-h patch test was significant. There were individual variations in the irritant potential of the soaps/cleansers in the volunteers, thus when the patient queries on what soap to use, it may be advisable to test each patient separately and educate him/her regarding the soaps/cleansers less likely to cause irritation. The limitations of the study was that it was single blind and non-randomized as all the 14 soap solutions were applied on 15 volunteers in the first panel and subsequently all the 17 soap solutions were applied on eight volunteers in the second panel. However, we could compare the irritant potential of 31 cleansers. The results of 24-h patch testing of 31 soaps/cleansers in the Indian market in two panels of 14 and 17 soaps/cleansers on 15 and eight volunteers, respectively, are presented.     

Influence of cleansing on stratum corneum tryptic enzyme in human skin

Desquamation in human skin is a well-balanced process of de novo production of corneocytes and their shedding from the skin surface. The proteolysis of corneodesmosomes is an important step in the final desquamation process. In the degradation of these adhesion molecules, the stratum corneum tryptic enzyme (SCTE) plays a key role. In initial studies with extracts of porcine epidermis, SCTE was shown to be inactivated by low concentrations of sodium lauryl ether sulphate (SLES). These in vitro findings were supported by in situ results obtained by measuring the release of fluorescent dyes coupled to trypsin-specific substrates incubated on human skin cross-sections. Moreover, in further studies, it could be demonstrated that the SCTE activity in the human horny layer decreases after in vivo application of cleansing products containing SLES. After repeated washing of human volunteers with tap water, a standard market cleansing product (SLES/betaine system) or a new improved cleansing product (SLES/betaine/disodium cocoyl glutamate system), the specific SCTE activity was determined in extracts from the uppermost layers of the stratum corneum. It could be shown that after application of the new formula the remaining SCTE activity was significantly higher than after use of the standard market formula. This ex vivo approach has proven to be very helpful for measuring surfactant effects on human skin enzymes. Using this assay, we developed an improved shower gel formula, which leads to a significantly higher skin enzyme activity after application, compared to a standard market formula.