Analysis and quantification of parabens in cosmetic products by utilizing hollow fibre-supported liquid membrane and high performance liquid chromatography with ultraviolet detection

A simple and direct method based on hollow fibre-supported liquid membrane (HFSLM) extraction and liquid chromatography equipped with a UV detector was developed for analysis and quantification of parabens in cosmetic products. The parabens analysed included methyl, ethyl, propyl, isobutyl and butyl paraben. The HFSLM extraction was carried out by employing di- n -hexyl ether as organic liquid that was immobilized in the hollow fibre membrane. The HFSLM extraction is simple, cheap, minimizes the use of solvents and uses disposable material. In an investigation of 11 paraben-containing cosmetic products, the levels of parabens (sum of all parabens in a product) ranged from 0.43% to 0.79% (w/w) for skin care products, 0.07–0.44% for hair fixing gels and 0.30–0.52% for soap solutions. The levels of individual parabens in individual cosmetic products ranged between 0.03% and 0.42% w/w for skin care products, 0.07% and 0.26% w/w for hair fixing gels and between 0.11% and 0.34% w/w for soap solutions. Parabens were found in the highest concentrations in skin care products followed by soap solutions and the least amounts were found in hair fixing gels. Of the paraben-containing products tested, all of them contained methyl paraben and about 90% contained propyl paraben in addition to methyl paraben. One product contained all the parabens analysed.     

The function of polyglyceryl erucate/isostearate/ricinoleate

Today, it is said that the formula design of cosmetics from ingredients of plant origin is an indispensable way and trend. From this consideration, cosmetic materials made from animal and synthetic petroleum ingredients are becoming less usable. Instead, cosmetic materials are designed from ingredients of plant origin and many and various botanical ingredients are being developed. Lanolin, which is one of the animal-based ingredients, is said to have ideal functions as a cosmetic oil, and it has been used in many fields such as make-up cosmetics as well as hair and skin care products for a long time. However, unfortunately, lanolin is an animal-based ingredient; therefore, the development of a botanical ingredient to replace lanolin was desired. Polyglyceryl-8 decaerucate/isostearate/ricinoleate, which we have developed, is an ester oil originating from plants and has an equivalent or higher function than lanolin. We have confirmed that our developed ester oil has various excellent characteristics such as a water-holding capability 2.5 times higher than that of lanolin, high air permeability, moisture keeping in dermal layers, protection of hair from changes in external environmental humidity, and excellent gloss and excellent dispersability of pigments. Thus, this newly developed ester oil is expected to be a promising new botanical cosmetic ingredient which can be applied in various fields.     

Human synthetic sebum formulation and stability under conditions of use and storage

The human skin surface and hair are generally coated with a thin film of liquid phase sebaceous lipids. This surface lipid film contributes to the cosmetic properties of the skin. Synthetic sebum has been used for studies on properties of skin and hair. However, there has been no standardized formulation of synthetic sebum and many of the synthetic sebum formulations that have been used do not closely resemble actual sebum. In this study, a formulation for a standardized and inexpensive synthetic sebum is proposed, and the chemical stability of this lipid mixture is demonstrated under conditions of use and storage. The proposed synthetic sebum consists of 17% fatty acid, 44.7% triglyceride, 25% wax monoester (jojoba oil) and 12.4% squalene. This lipid mixture takes up approximately 6% of its weight in water when equilibrated in an atmosphere saturated with water vapour. It is stable on exposure to the atmosphere at 32°C for at least 48 h, and it is also stable on storage at 4 or −20°C, either dry or in chloroform : methanol solution for at least 6 months. This synthetic sebum could be useful in studies on cosmetic properties of the skin surface or hair, on penetration of chemicals into the skin or in development of standardized tests of laundry detergent performance.     

Coenzyme Q10 has anti-aging effects on human hair

IFSCC Magazine, 11 (2008) (1) 37–42 Ubiquinones are the most widespread and therefore best investigated bioquinones. Due to their hydrophobic isoprenoid side chain, ubiquinones can be solubilized in organic solvents or lipids but are insoluble in water. Using a specific emulsifier system it has been possible to deliver positive effects to biological systems also from aqueous formulations. Ubiquinone‐50, also referred to as coenzyme Q10, is well known in cosmetic science and especially in skin care because of its antioxidant activity. It is found in the membranes of peroxisomes, lysosomes, vesicles, the endoplasmic reticulum and notably in the inner membrane of the mitochondrion, where it is an important part of the electron transport chain. Using coenzyme Q10 in the proposed emulsifier system we could show that the molecule not only has relevance as an anti‐aging bioactive in skin care but also has positive effects on the human hair follicle. The hair follicle is a complex mini organ and synthesis of hair keratin, the major component of hair fibers, is an essential prerequisite for the growth of strong and healthy hair. But like all biological systems the hair follicle, the biologically active part of the hair, also undergoes an aging process associated among other things with a decline in certain hair keratins. Due to this age‐related shift in basic structural proteins of the hair shaft, mature hair often becomes fragile and difficult to manage. Therefore it is a challenge for cosmetic science to provide bioactives to fight age‐related changes and maintain a youthful appearance of hair. Using cultivated hair follicle keratinocytes we identified coenzyme Q10 as a potent bioactive that stimulates the gene expression of different hair keratins, especially those which are reduced during aging processes in hair follicles. These results led us to investigate a shampoo and a tonic formulation enriched with coenzyme Q10 in a placebo‐controlled panel study. In a left/right comparison a group of healthy volunteers older than 40 years of age applied the formulations daily for 4 days. Throughout the test period the gene expression of different hair keratins from plucked hair follicles was determined using quantitative polymerase chain reaction techniques. Subsequent statistical analysis revealed an increase in age‐relevant hair keratins in human hair roots treated with coenzyme Q10, thus pointing out the striking benefits of coenzyme Q10 in hair care formulations. We conclude that coenzyme Q10 is an ideal ingredient for hair care formulations, providing anti‐aging properties through activation of specific keratins aligned with the needs of mature hair.     

Role of proteins in cosmetics

The review critically evaluates the safety and effectiveness of proteins or peptides in cosmetic formulations designed for skin and hair care. Special attention is paid to soluble collagen and the use of this fibrillar protein in combination with detergents.
The authors indicate various misconceptions on the mechanism of the effect of collagen and possible risks if the formulations containing collagen are not used on intact skin. Besides the moisturizing effect of collagen on the stratum corneum, the formation of a protective layer on the surface of the skin or hair, and the formation of complexes with detergents and the mechanisms of the effectiveness of this protein are considered.
Le role des proteines dans les cosmetiques     

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。     

Potential of polar lipids from bovine milk to regulate the rodent dorsal hair cycle

Among the lipids in bovine milk, minor components such as conjugated linoleic acids and phospholipids are more attractive than triacylglycerols from the standpoint of biological activity. To explore novel functions of bovine milk polar lipids (MPL), topical application to murine dorsal skin was introduced as an assay system. The acetone-insoluble lipid fraction derived from bovine milk was dispersed in ethanol and applied to 9-wk-old C57BL/6N female mice for 3 wk. In combination with visual assessment of the dorsal pigmentation, the progression of the hair cycle was estimated by calculating the ratio of subcutis to dermis thickness. The administration of MPL led to earlier progression of the hair cycle compared with administration of the vehicle. In some cases, the extent of MPL-induced hair cycle progression was comparable to that in animals treated with minoxidil, the most well-known reagent that initiates anagen. These results indicate that the MPL preparation contains a dermal penetrative component that can regulate the hair cycle and, thus, this preparation possesses potential for cosmetic use.     

Ethylene formation from methionine as a method to evaluate oxygen free radical scavenging and metal inactivation by cosmetics

It has been proposed that oxygen free radicals are involved in skin aging. This paper describes a new method for the evaluation of oxygen free radical scavenging by cosmetic products. It is based on the measurement, by gas chromatography, of ethylene produced during the oxidation of methionine by the hydroxyl radical. OH· is produced by an iron catalyzed superoxide-driven Fenton reaction in which superoxide is obtained by photochemical oxygen reduction. The cosmetic is applied, together with methionine, riboflavine, NADH, FeCl₃ and EDTA, on a glass microfibre filter and submitted to UVA exposure through a quartz cell. Ethylene is then measured from aliquots of the atmosphere inside the cell. Catalase or Desferal completely inhibits ethylene production. SOD or high concentrations of hydroxyl radical scavengers (Mannitol, DMSO etc. ) afford a partial protection. Thus the efficiency of O₂⁻·, H₂O₂ and OH· scavengers and iron chelators can be measured. The main advantage of this test is that it is performed in conditions which simulate skin during UV exposure (e.g. air and UV exposed thin layer). Furthermore, as it is non-invasive, it can also be applied to human skin in vivo.     

Contribution to the quantification of the conditioning effects of hair dyes

Apart from the problem of colour, the cosmetic properties of hair after dyeing play a vital role both for the cosmetic chemist and the user.
A methodology for a quantitative assessment of these conditioning effects is proposed.
This methodology is based on a realistic approach to the protocols, and uses original apparatus and accessories which take the particular context of the dyeing process into account.
Particular importance is given to studying the length of set hold and the ease of combing. Big differences were observed between three dyes on sale on the market, including their finishing treatment products such as shampoo or rinse.
Contribution à la quantification des effets conditionnants des teintures     

Caffeine improves barrier function in male skin

The influence of androgens, especially testosterone and its effector dihydrotestosterone, results in a constitutive disadvantage for male skin, e.g. reduced viability of hair at the scalp and reduced epidermal permeability barrier repair capacity. Dihydrotestosterone can act, among others, as an adenyl cyclase inhibitor. Caffeine on the other hand is an inexpensive and (in regular doses) harmless substance used in various cosmetic products, which can act as a phosphodiesterase inhibitor. To prove the hypothesis that caffeine as a phosphodiesterase inhibitor is able to override testosterone-induced effects on barrier function, we performed a double-blind placebo controlled study with healthy volunteers. In this study, 0.5% caffeine in a hydroxyethylcellulose gel preparation (HEC) was applied on one forearm, HEC without caffeine on the other forearm of male and female volunteers for 7 days and transepidermal water loss (TEWL) was measured before and at the end of the treatment period. Basal TEWL did not differ significantly between male and female subjects but the application of caffeine significantly reduced TEWL in male skin compared with female skin. We conclude that caffeine is beneficial for barrier function in male skin.     

An analytical method for the determination of betaine (trimethylglycine) from hair

Hair fibres have no active renewable protective mechanisms yet hair (wool and fur) provides an essential protective function. Therefore, it is possible that hair contains a number of internal components to maintain fibre and protein structure and function through a range of normal environmental conditions. Trimethylglycine (betaine) provides cellular and protein protection during times of high osmotic stress and low water concentrations. These conditions are very pertinent to everyday cosmetic procedures such as shampooing, bleach or perming. Therefore, we have conducted preliminary investigations to establish the presence of natural betaine in hair as a possible ingredient to provide protection and maintain protein function. Using an high performance liquid chromatography (HPLC) technique designed for the analysis of betaine in blood and urine, we have demonstrated, via simple hot water extraction, a measurable level of betaine in blood and human hair. Further, we have demonstrated, in principle, the possibility of adding betaine back to the fibre via cosmetic products such as shampoos.     

The regulatory role of the tetrapeptide AcSDKP in skin and hair physiology and the prevention of ageing effects in these tissues – a potential cosmetic role

The naturally occurring tetrapeptide acetyl‐N‐Ser‐Asp‐Lys‐Pro (AcSDKP) recognized as a potent angiogenic factor was shown recently to contribute to the repair of cutaneous injuries. In the current article, we report the ability of AcSDKP to exert a beneficial effect on normal healthy skin and scalp and to compensate for the ageing process. In vitro AcSDKP at 10^?11–10^?7 M significantly stimulates the growth of human keratinocytes, fibroblasts and follicle dermal papilla cells. Moreover, it enhances the growth of human epidermal keratinocyte progenitor and stem cells as shown in a clonogenic survival assay. Topical treatment of ex vivo cultured skin explants with 10^?5 M AcSDKP increases the thickness of the epidermis and upregulates the synthesis of keratins 14 and 19, fibronectin, collagen III and IV as well as the glycoaminoglycans (GAGs). In the ex vivo‐cultured hair follicles, AcSDKP promotes hair shaft elongation and induces morphological and molecular modifications matching the criteria of hair growth. Furthermore, AcSDKP at 10^?11–10^?7 M was shown to improve epidermal barrier, stimulating expression of three protein components of tight junctions (claudin‐1, occludin, ZO‐1) playing an important role in connecting neighbouring cells. This tetrapeptide exercises also activation of SIRT1 implicated in the control of cell longevity. Indeed, a two‐fold increase in the synthesis of SIRT1 by cultured keratinocytes was observed in the presence of 10^?11–10^?7 M AcSDKP. In conclusion, these findings provide convincing evidence of the regulatory role of AcSDKP in skin and hair physiology and suggest a cosmetic use of this natural tetrapeptide to prevent skin ageing and hair loss and to promote the cutaneous regeneration and hair growth.     

Change in surface chemistry of the cuticle of human hair by chemical and photochemical oxidation

This is a multifaceted study on the characterization and quantification of damage to the hair fiber surface caused by photochemical and cosmetic chemical oxidative processes. Unique techniques were used, including a microfluorometric method that had been adapted to characterize and quantify the delipidation and acidification of the human hair surface during light exposure and cosmetic chemical grooming processes such as bleaching. During photochemical and chemical oxidation, breakdown of the lipid domains (also called the F‐layer) of the outer b‐layer occurs on the exposed scale faces and cysteic acid groups are generated on the cuticle cell surface. The newly formed acid functionalities can be tagged with the cationic fluorochrome Rhodamine B, allowing not only quantification of the level of progressive acidification but also localization of the newly formed acid functionalities. On the other hand, the negative charges generated on the hair surface by oxidation can also bind low molecular weight quaternary cationic conditioning compounds such as cetyltrimethylammonium bromide. This process can be considered a relipidation by adsorption. We have shown that the entire process of delipidation/acid formation and subsequent relipidation by adsorption on the scale faces can be quantified by X‐ray photoelectron spectroscopy. Since X‐ray photoelectron spectroscopy analysis is highly sensitive and able to detect atomic species at the very surface of the hair fibers, receiving signals from an escape depth as shallow as 25 Å, it appeared ideal for the characterization of treatment‐induced changes in the hair surface. However, X‐ray photoelectron spectroscopy provides an average elemental composition of the hair surface including scale faces and scale edges. The microfluorometric technique, on the other hand, can distinguish progressive delipidation of the scale faces from changes occurring at the broken scale edges. This distinction was shown and characterized in detail by slow speed microfluorometric scanning of the hair surface. Chemical and photochemical oxidative processes at the hair surface result in certain collateral effects. Particularly changes in surface wettability and fiber friction are of significance to the cosmetic chemist because they affect the spreading and wicking of products in hair as well as the managability and the body of hair assemblies. Methods of characterizing these effects are discussed briefly.     

High spatial resolution study of human skin using synchrotron infrared microscopy: application to the penetration of external agents

Human skin sections were studied using synchrotron-powered infrared microscopy. The superior lateral resolution achieved with this technique (diffraction-limited spot sizes) allows the detailed analysis of the biocomposition of the skin layers. It is shown that highly organized lipids are present in the stratum corneum, as evidenced by a slight frequency difference in the symmetric stretch mode of the methylene groups. Biochemical images were generated showing the precise location of the lipids, proteins and collagen across the skin section. More enhanced images were generated using a statistical approach (fuzzy C-means clustering). Penetration of two external agents (cyanophenol and a cosmetic compound, ethylhexyl methoxycinnamate) was studied. The penetration pathway across the stratum corneum is favored at locations of lower lipid concentration. Both compounds penetrated into the epidermis, but neither of them induced a change in the protein secondary structure. It was shown that hair follicle is a favored penetration pathway for these agents.     

Headspace analysis study of evaporation rate of perfume ingredients applied onto skin

Diffusion of perfume ingredients from skin or hair is measured using an original method based on dynamic headspace technology. This has been used for pure odorants, fine fragrances, as well as for perfumed cosmetic applications such as soaps, creams or shampoos, in order to characterize diffusion processes and air/skin or air/hair partitioning. Accordingly, a special collection system, applied on the inner face of the forearm, has been developed, allowing the adsorption of diffusing organic vapours from skin onto Tenax (poly-diphenyl phenylene oxide) with a controlled air flow rate. A simple model composition containing eleven volatile synthetic odorants was prepared in an alcoholic matrix and the solution was applied onto the skin. The diffusion rate of the different components was measured by determining the concentration of each in the gas phase versus time. Conversely, the same experiment was effected by the application of an alcoholic solution of each individual component. In this manner, the relative diffusion from skin of the components alone or mixed was compared using the same experimental technique. The effect of a musky component was also tested. Both compositions (with and without musk) were then applied in a soap base. Thus, following a rigorous protocol, the forearm was washed with the perfumed soap and rinsed with water before collection of the headspace. The results show the different diffusion rates of the individual odorants. In particular, components evaporate slower from the skin when they have been applied from a soap bar compared to when they have been applied from alcoholic solution. We also present results describing the characterization of skin types using a panel comprised of 80 people (40 females and 40 males); amount of sebum, hydration and pH were systematically measured on different parts of the face, the neck as well as the outer and inner faces of the forearm. The panelists were then classified into different sub-groups taking into account these parameters. It should be noted that the foregoing results were obtained on an ‘average’skin type.     

A highly sensitive method to determine the washing resistance of artificial hair colours

Citation: IFSCC Magazine, 11 (2008) (2) 139–142 Abstract: Due to the improved performance of modern hair colorants, the high natural variability in hair qualities and the individual influences of manual product applications, colour care effects of cosmetic treatments are very difficult to detect. A new, highly sensitive test method to study the colour fading behaviour of human hair was established for a large variety of cosmetic treatments. This method is based on an automatic multistage application of standard wool tissues combined with automatic colour evaluation by means of CIE L × a × b × measurements (DIN 5033). The delta E values are the main interest because they include all information regarding the L (black vs. white), a (red‐green) and b (blue‐yellow) axes defined in the Hunter Lab colour space. For validation of this new method, different permanent and non‐permanent hair colour shades were applied to undamaged light brown Caucasian hair strands. The hair strands were washed manually stepwise 30 times and the colour loss compared with the results obtained on wool tissues using an automatic application system. For most of the investigated hair colours, a coefficient of determination of r2 > 0.99 was achieved. Modern permanent hair colours show a high resistance to cosmetic treatments. Over 90% of the initial colour result was retained after 30 product applications. Shampoo and conditioner formulations induce different degrees of colour loss in hair. In basic formulas significant influences of single surfactants could be detected. The new method using wool tissues correlates very well with that using manually washed Caucasian hair strands. This automatic method is very time‐effective and offers an excellent reproducibility with a high sensitivity for assessing product influences on artificial hair colours. Keywords: Color fading, color protection, color retention, hair color resistance, hair wash simulation Paper presented at the IFSCC Conference 2007, Amsterdam, The Netherlands     

Dynamic mechanical study of hair viscoelasticity and softness

IFSCC Magazine , 12 (2009) (2) 93–98
Dynamic mechanical analysis (DMA) has been widely used to investigate material properties such as thermal transitions and complex modulus of polymers. Until now, only a few articles have been published to discuss applications of DMA in studying human hair and evaluating hair care products due to difficulties in handling hair samples. In DMA, a complex modulus (E*), an elastic (storage) modulus (E') and an imaginary (loss) modulus (E') are determined which give a better characterization of viscoelastic properties of hair than regular tensile strength. A new DMA test methodology including a hair bundle preparation and sample clamping technique was developed and applied to study human hair samples. Effects of hair type (Caucasian vs. Asian), bleaching time, environmental relative humidity (RH), and cosmetic treatments on hair viscoelasticity and storage bending modulus/stiffness were investigated. Average complex modulus and Young's modulus of single hair fibers and storage bending modulus of hair bundles before and after cosmetic treatments at various relative humidity levels were determined. Subjective evaluations of hair soft feel by salon panelists were conducted and the results compared with those of objective measurements (changes in hair storage bending modulus).
Keywords: Dynamic mechanical analysis, hair, viscoelasticity, softness, quaternium-91
This paper was presented at the 25th IFSCC Congress 2008, Barcelona, Spain     

Cinnamic acid derivatives in cosmetics: current use and future prospects

Cinnamic acid derivatives are widely used in cosmetics and possess various functions. This group of compounds includes both naturally occurring and synthetic substances. On the basis of the Cosmetic Ingredient Database (CosIng) and available literature, this review summarizes their functions in cosmetics, including their physicochemical and biological properties as well as reported adverse effects. A perfuming function is typical of many derivatives of cinnamaldehyde, cinnamyl alcohol, dihydrocinnamyl alcohol and cinnamic acid itself; these substances are commonly used in cosmetics all over the world. Some of them show allergic and photoallergic potential, resulting in restrictions in maximum concentrations and/or a requirement to indicate the presence of some substances in the list of ingredients when their concentrations exceed certain fixed values in a cosmetic product. Another important function of cinnamic acid derivatives in cosmetics is UV protection. Ester derivatives such as ethylhexyl methoxycinnamate (octinoxate), isoamyl p‐methoxycinnamte (amiloxiate), octocrylene and cinoxate are used in cosmetics all over the world as UV filters. However, their maximum concentrations in cosmetic products are restricted due to their adverse effects, which include contact and a photocontact allergies, phototoxic contact dermatitis, contact dermatitis, estrogenic modulation and generation of reactive oxygen species. Other rarely utilized functions of cinnamic acid derivatives are as an antioxidant, in skin conditioning, hair conditioning, as a tonic and in antimicrobial activities. Moreover, some currently investigated natural and synthetic derivatives of cinnamic acid have shown skin lightening and anti‐ageing properties. Some of them may become new cosmetic ingredients in the future. In particular, 4‐hydroxycinnamic acid, which is currently indexed as a skin‐conditioning cosmetics ingredient, has been widely tested in vitro and in vivo as a new drug candidate for the treatment of hyperpigmentation.     

Temperature as a moisture cue in haptics on hair

A mechanism for giving a moisturized or dried‐out feeling to hair was investigated. A two‐step approach was conducted in order to elucidate the issue. First, we have reviewed previous studies that are related to the sensory perception of materials not only in cosmetic industry but also in other fields, such as textile and architecture industries, and established a hypothesis. Second, we have verified the hypothesis derived from the first step and identified the mechanism for the moisturized or dried‐out feeling that people feel by measuring the heat transfer characteristic, q_max. The results revealed that the moisturized or dried‐out feeling that people feel at the moment of contact with hair was highly related to the temperature drop at the skin surface. The results also revealed that the moisturized or dried‐out feeling strongly depends on the hair shape (meandering and diameter), surface damage and the water content of hair fibres which constitute the hair swatch. The moisturized feeling, however, was not related to the water content of hair fibres at a constant relative humidity (RH), as the differences in the water content of the hair fibres at a constant RH were too small for the recognition of the difference in the moisturized feeling.