Showing papers in "Journal of Cosmetic Science in 2005"

Quantitative model of cellulite: three-dimensional skin surface topography, biophysical characterization, and relationship to human perception.

Abstract: Gynoid lipodystrophy (cellulite) is the irregular, dimpled skin surface of the thighs, abdomen, and buttocks in 85% of post-adolescent women. The distinctive surface morphology is believed to result when subcutaneous adipose tissue protrudes into the lower reticular dermis, thereby creating irregularities at the surface. The biomechanical properties of epidermal and dermal tissue may also influence severity. Cellulite-affected thigh sites were measured in 51 females with varying degrees of cellulite, in 11 non-cellulite controls, and in 10 male controls. A non-contact high-resolution three-dimensional laser surface scanner was used to quantify the skin surface morphology and determine specific roughness values. The scans were evaluated by experts and naive judges (n=62). Body composition was evaluated via dual-energy x-ray absorptiometry; dermal thickness and the dermal-subcutaneous junction were evaluated via high-resolution 3D ultrasound and surface photography under compression. Biomechanical properties were also measured. The roughness parameters Svm (mean depth of the lowest valleys) and Sdr (ratio between the roughness surface area and the area of the xy plane) were highly correlated to the expert image grades and, therefore, designated as the quantitative measures of cellulite severity. The strength of the correlations among naive grades, expert grades, and roughness values confirmed that the data quantitatively evaluate the human perception of cellulite. Cellulite severity was correlated to BMI, thigh circumference, percent thigh fat, architecture of the dermal-subcutaneous border (ultrasound surface area, red-band SD from compressed images), compliance, and stiffness (negative correlation). Cellulite severity was predicted by the percent fat and the area of the dermal-subcutaneous border. The biomechanical properties did not significantly contribute to the prediction. Comparison of the parameters for females and males further suggest that percent thigh fat and surface area roughness deviation are the distinguishing features of cellulite.

L-Ergothioneine scavenges superoxide and singlet oxygen and suppresses TNF-alpha and MMP-1 expression in UV-irradiated human dermal fibroblasts.

Abstract: Ergothioneine (EGT) is a sulfur-containing amino acid, and is presumed to function as a natural antioxidant. The purpose of this study was to identify the nature of the antioxidant activity and investigate the effects of EGT on UV-induced cellular response. In chemical studies, EGT scavenged the superoxide anion radical (*O(2)(-)) and singlet oxygen ((1)O(2)). In cultured fibroblasts, EGT suppressed TNF-alpha up-regulation by UVB irradiation. In addition, in fibroblasts exposed to UV-A, EGT suppressed the expression of matrix metalloproteinase 1 (MMP-1) protein by nearly 50% and reduced MMP-1 mRNA expression. From these results, we conclude that EGT scavenges reactive oxygen species generated by both Type I and Type II photosensitization and suppresses both TNF-alpha expression and MMP-1 at their transcriptional level. EGT may reduce skin anti-aging effects after UV irradiation by the scavenging of *O(2)(-) and (1)O(2), and reducing signals for protease and inflammatory activity.

Study of sensory properties of emollients used in cosmetics and their correlation with physicochemical properties.

Abstract: Eight liquid emollients (mineral oil, sunflower oil, squalane, decyl oleate, isopropyl myristate, octyldodecanol, dimethicone, and cyclomethicone) were characterized by instrumental and sensory methods and evaluated to determine the relationship between sensory and instrumental measures. Sensory analysis was carried out by a panel of 14 assessors, who evaluated the following attributes: difficulty of spreading, gloss, residue, stickiness, slipperiness, softness, and oiliness. The physicochemical properties measured were spreadability (at one-half minute and at one minute), viscosity, and superficial tension. Data collected were statistically analyzed by analysis of variance (ANOVA), principal component analysis (PCA), and linear partial least squares regression analysis (PLS). In consideration of their physicochemical characteristics, the studied emollients were sorted into three groups, in which the silicones distinctly separate from the rest. Sensory characteristics enabled the discrimination of four groups of emollients where, besides the two silicones, isopropyl myristate was also differentiated. PLS revealed that emollient sensory attributes could be well predicted by instrumental measurements.

Characterization of the lipid composition at the proximal root regions of human hair.

Abstract: The hair lipid composition collected from 44 Japanese females between 1 and 81 years of age was examined for eight lipids including hydrocarbons (HCs), squalene (SQ), wax esters (WEs), triglycerides (TGs), fatty acids (FAs), cholesterol (CH), ceramides (CERs), and 18-methyl eicosanoic acid (MEA). In this study, the 5-cm length from the proximal root end of hair fibers, which had never been exposed to any chemical treatment, was used after 5-min incubation with hexane following shampooing. Hair lipids were extracted with solvent and subsequent alkali-solvent and were then analyzed by a combination of chromatography. Although the average contents of the lipids showed great fluctuations among individuals, there were significant correlations between the levels of each lipid, which allowed for the classification of the hair lipids into four groups: group A: SQ, WEs, TGs, and FAs (designated as endogenous lipids based upon their sebum origin); group B: CH and CERs (designated as endogenous lipids); group C: HC (unknown origin); and group D: MEA (the other endogenous lipid). A principal component analysis for eight lipids revealed that the hair lipid composition was characterized by a predominant negative correlation between each lipid for groups A and B. This negative correlation suggests that the endogenous lipids in group B serve as a barrier against the penetration of predominantly sebum-derived exogenous lipids (group A). Endogenous lipids consisting of CH and CERs (group B) and MEA (group D) should be designated as intrinsic internal lipids of human hair.

Surfactants, polymers and their nanoparticles for personal care applications.

Abstract: A "touch me not" plant folding up rapidly upon being attacked or microbes depositing on teeth or ocean vessels even under hostile conditions are examples in nature that provide inspiration for developing new classes of personal care release or deposition systems. In this paper, development of such systems based on polymer/surfactant colloid chemistry is explored for achieving transport and release of cosmetic and pharmaceutical molecules at desired rates at desired sites. The successful development of products depends upon understanding and utilizing key interactions among surfactants, polymers and hybrid polymers that are relevant to personal care products. Thus, the absorbed layers or tethers on the particulates can be manipulated for desired dispersion of actives or depositions on substrate under any and all conditions. New hybrid polymers and nanogels have been synthesized for tuning up nanodomains that can extract and deliver at will cosmetics/drugs/toxins by perturbing pH, temperature or ionic strength of the system. Particularly, hydrophobically modified polymers have features of both polymers and surfactants and due to the associative nature of the hydrophobic groups, such polymers can form intramolecular nanodomains for performing carrier functions. Nanogels developed recently include that of polyacrylamide, poly(acrylic acid) and starch nanogels modified for extraction and subsequent slow release of fragrances and overdosed toxic drugs. Binding and release processes were investigated using surface plasmon resonance and fluorescence spectroscopies, powerful techniques for monitoring short term and long term changes.

Hemp-seed and olive oils: their stability against oxidation and use in O/W emulsions.

Abstract: Hemp-seed oil has several positive effects on the skin: thanks to its unsaturated fatty acid (PUFA) content it alleviates skin problems such as dryness and those related to the aging process. We present a comparative study of hemp-seed and olive oils, determining some physicochemical indices and evaluating their stability against oxidation. The peroxide value of hemp-seed oil was below 20, the threshold limit for edible oils. Hemp-seed oil was less stable against peroxidation than olive oil, but MDA and MONO assays showed its stability to be above expectations. The chlorophyll contained in extra virgin olive oil had a higher photostability than that contained in hemp-seed oil, possibly due to the larger amount of antioxidant in the olive oil. A certain amount of Vitamin E was found in hemp-seed oil. Since quality analyses indicated that hemp-seed oil is relatively stable, emulsions were prepared with the two oils, and their stability and rheological characteristics were tested. Some of the resulting gel-emulsions were suitable for spraying on the skin.

Detection thresholds of capsaicin: a new test to assess facial skin neurosensitivity.

Abstract: The goal of this study was to assess the accuracy/reliability of a new test designed to measure cutaneous neurosensitivity. The test was carried out on a random population of 150 healthy adult women and was based on the determination of individual detection thresholds of topically applied capsaicin. Five capsaicin concentrations were used in 10% ethanol aqueous solution (3.16 x 10(-5)%; 1 x 10(-4)%; 3.16 x 10(-4)%; 1 x 10(-3)%; 3.16 x 10(-3)%). The methodology used to attain the detection threshold was capsaicin application in increasing concentration on the nasolabial folds. The vehicle was simultaneously applied following a split-face, single-blind plan. The test was stopped as soon as the subject reported a specific sensation lasting more than 30 seconds on the capsaicin side. The safety of the test was judged as excellent by the panelists since all the reported sensations were considered as slightly or moderately perceptible. The test allowed the classification of the test population according to six threshold levels corresponding to the sensitive reaction to one of the five capsaicin concentrations and to the absence of sensitivity to the highest concentration. Surprisingly, the distribution of the population was not unimodal and seemed to reveal the existence of two different sub-groups: individuals with a low capsaicin detection threshold and those with a high threshold. These two sub-populations strongly differed in their respective self-perception of sensitive skin. The higher the self-declared sensitive skin incidence was, the lower the detection threshold was. This new test of skin neurosensitivity is easy, quick, and truly painless. It appears to be a promising tool for the cosmetic diagnosis of sensitive skin.

Stability study of lipoic acid in the presence of vitamins A and E in o/w emulsions for cosmetic application

Abstract: The effectiveness of any cosmetic product containing a functional ingredient is determined by the skin delivery of the active molecule, which is influenced by the type of carrier and the molecule itself. Furthermore, the functional ingredient should be stable in the formulation. The purpose of this paper is to study the stability of lipoic acid in the presence of vitamins A (as palmitate) and E (as acetate) in semisolids for cosmetic use. The systems formulated were studied in regard to their aspect, pH, stability under centrifugation, and rheological behavior. The chemical analyses of lipoic acid and vitamins A and E were carried out by HPLC after studying the specificity of the method employed in each case. The quantitation of the active principles was performed by HPLC with C18 (5 microm) columns. The mobile phase was methanol for the vitamins, with spectrophotometric detection at 325 nm for vitamin A and 230 nm for vitamin E. The mobile phase for lipoic acid was methanol:water (80:20) and phosphoric acid at pH 3.0, with spectrophotometric detection at 332 nm. All systems were stable to centrifugation, and no significant modification of rheological behavior was observed in relation to the base emulsion used as control. The chemical studies performed indicated that although lipoic acid is not very stable in these formulations, the presence of vitamin A favors its chemical stability.

Topical application of Bifidobacterium-fermented soy milk extract containing genistein and daidzein improves rheological and physiological properties of skin

Abstract: The authors examined the effects of Bifidobacterium-fermented soy milk extract (BE) containing genistein and daidzein on the hyaluronic acid (HA) content and rheological and physiological properties of hairless mouse and/or human skin. Topical application of BE for six weeks significantly restored changes in the elasticity and viscoelasticity of mouse skin, increased the HA content, and hydrated and thickened mouse skin. Also, topical application of a gel formula containing 10% BE to the human forearm for three months significantly lessened the decrease in skin elasticity. Therefore, BE is expected to become a new cosmetic ingredient to prevent the loss of skin elasticity through enhancement of HA production.

Refractive index matching and clear emulsions.

Abstract: Refractive index (RI) matching is a unique way of making clear emulsions to meet market trends. However, RI matching has not been sufficiently investigated in terms of physical principles and methodologies. Snell's law (n2 sin r2= n1 sin r1) is applicable to cosmetic emulsions. When oil phase and water phase have equal RI (n2 = n1) values, light will not bend as it strikes obliquely at the emulsion interface. Instead, light is transmitted through the emulsion without refraction, which produces clarity. Theoretical RI values in solution can be calculated with summation of the product of the weight percentage and refractive index of each ingredient (RI(mix) = [W1 x n1 + W2 x n2 + W3 x n3 + + Wn x nn]Wtau). Oil-phase RI values are normally at 1.4 or higher. Glycols are used to adjust the water phase RI, since they typically have larger RI values than water. Noticeable deviations from calculated RI values are seen in experimentally prepared solutions. Three basic deviation types are observed: negative, positive, and slightly negative or positive, which can occur in glycol aqueous solutions at different concentrations. The deviations are attributed to changes in molecular interaction between molecules in solution, which can lead to changes in specific gravity. Negative RI deviation corresponds to a decrease in specific gravity, and positive RI deviation corresponds to an increase in specific gravity. RI values will deviate from calculated values since an increase or decrease in specific gravity leads to a change in optical density.

Reaction characteristics of a tooth-bleaching agent containing H2O2 and NaF : In vitro study of crystal structure change in treated hydroxyapatite and chemical states of incorporated fluorine

Abstract: This in vitro study was performed to elucidate the reaction mechanism of sodium fluoride (NaF), which is added to tooth-bleaching agents to lessen the adverse effect of hydrogen peroxide (H2O2) on teeth. Both hydroxyapatite (HAP) and dihydrated dicalcium phosphate (DCPD), model substances for dental hard tissues, dissolved easily in a simple H2O2 solution. In the H2O2/NaF solutions, however, fluorine compounds that could not be identified by X-ray diffraction (XRD) due to the smallness of the products were formed on the surface of the HAP. X-ray photoelectron spectroscopy (XPS) studies demonstrated that fluoridated hydroxyapatite (FHAP) was formed on HAP, and that calcium fluoride (CaF2) formation was accelerated by increasing the concentrations of fluorine and H2O2 along with the partial dissolution of HAP. In H2O2/NaF solution, DCPD also transformed easily to FHAP and CaF2, which are favorable to the remineralization process on the tooth surface. Thus, the mechanism of NaF was elucidated, and its use together with H2O2 for tooth bleaching was proved to be effective. Methodologically, the XPS two-dimensional plot made it possible for the first time to directly estimate the ratio of FHAP and CaF2 in the reaction products, in contrast to the conventional wet-analytical method, which is simply based on the difference in solubility of the two components.

Dissimilar effect of perming and bleaching treatments on cuticles: Advanced hair damage model based on elution and oxidation of S100A3 protein

Abstract: Hair treatment chemicals induce sudden and severe hair damage. In this study, we examined cuticles from untreated, permed, and bleached hair that were mechanically discriminated by shaking in water. Both perming and bleaching treatments are prone to easily delaminate cuticles. Confocal microscopy revealed that the cuticles of permed hair were delaminated with larger pieces than untreated ones. On the other hand, the cuticles of bleached hair tend to fragment into small peptides. At the minimum concentration of thioglycolate required to elute S100A3 protein from the endocuticle into the reductive permanent waving lotion, enlarged delaminated cuticle fragments were observed. Although S100A3 is retained in bleached hair, S100A3 is irreversibly oxidized upon bleaching treatment. It is likely that the oxidative cleavage of disulfide bonds between cuticle-constituting proteins, including S100A3, results in the fragile property of cuticles. Here we present a more comprehensive model of hair damage based on a diverse mechanism of cuticle delamination.

Effects of low-level hydrophobic substitution on conditioning properties of cationic cellulosic polymers in shampoo systems.

Abstract: A new class of cationic conditioning polymers (Polymer SL) has been prepared and evaluated in shampoo formulations. Polymer SL is a family of high viscosity quaternized hydroxyethyl cellulose (HEC) polymers with cationic substitution of trimethyl ammonium and dimethyldodecyl ammonium (Figure 1). SL compositions benefit from hydrophobic character to deliver superior conditioning performance in hair care applications. At the same time, low levels of hydrophobes have been chosen to assure good compatibility with surfactant systems without the complications of associative thickening. The polymers have been evaluated in clear shampoo formulations and two-in-one silicone containing shampoos using objective lab methods and subjective panel evaluation on hair tresses. Commercial conditioning polymers: Polyquaternium-10 (PQ-10) (UCARE Polymer LR-30M) and Guar Hydroxypro-pyltrimethylammonium Chloride (Jaguar C-13S) were used as performance benchmarks. The new hydrophobically-modified cationic polymers demonstrated superior performance in all major categories of conditioning and showed improved silicone deposition from two-in-one systems. Moreover, they retained other good qualities of their PQ-10 structural analogs such as enabling crystal clear formulations and showing no build-up or volume-down effects on hair. These new olymers were also found to be efficient conditioning agents in different surfactant systems with or without silicones.

Torsional method for evaluating hair damage and performance of hair care ingredients.

Abstract: In this study, we have developed a single hair fiber torsional pendulum method to determine the role of the cuticle and the cortex on torsional properties with respect to fiber cross-sectional area, fiber rigidity, and energy dissipation at 65% RH and in the wet state. Our results demonstrate that in fine diameter fibers with a high cuticle-to-cortex ratio, the cuticula exert a significant effect on the torsional deformation behavior of hair fibers at both normal humidities and in the wet condition. In addition, our data indicate that energy dissipation is confined to fibers with a high cuticle-to-cortex ratio, and the amount of energy dissipated becomes more pronounced with increasing water content. The torsional properties of hair spray-treated fibers suggest that the deposited hair spray film masks the properties of the base fiber and imparts its own dissipative character to the measurement. Since tensile mechanical properties are often used to make claims about the performance of hair care products, we have compared the results obtained from torsional and tensile measurements on over-processed bleached hair fibers conditioned with Polyquaternium-10 and cetyl trimethylammonium bromide (CETAB) to evaluate which method is more advantageous. Our data demonstrate that torsional measurements can distinguish hair care products which reinforce the cuticle from those which affect the cortex, while tensile measurements showed no significant differences.

Silicones used in permanent and semi‐permanent hair dyes to reduce the fading and color change process of dyed hair occurred by wash‐out or UV radiation

Abstract: Different kinds of silicones were incorporated directly into permanent and semi-permanent hair dyes To ensure that the silicone was deposited to the hair fibers Si deposition was measured Hair treated with a silicone free control or the silicone modified hair dyes was tested for color and lightness change (fading) by washing the treated tresses several times and measuring the color change In a second experiment, hair treated with permanent hair dye was treated with UV radiation to show if silicones can reduce the color change initiated by UV light The influence of the silicones to dry combing forces of permanent dyed hair untreated and treated with UV was also investigated The tests showed that dimethiconol/dimethicone mixtures can reduce the washout of hair colorant clearly and silicone resins like trimethylsiloxysilcate or propylphenylsilsesquioxane are able to decrease the color change occurred by UV radiation in dyed hair

Effect of hair color on luster

Abstract: The effect of color on instrumentally evaluated luster of hair dyed to different colors and depths of shades is studied. For natural hair colors, such as blond, brown, and black, the increase in luster with increasing color is associated with a decrease in diffusely scattered light as a result of light absorption by melanin granules. On dyed hair the interpretation of data from a goniophotometer (GP) is more complicated. Using the colors covering the extremes and middle of the visible spectrum, our results demonstrate how dye composition (single or multicomponent), concentration, and penetration depth into the fiber affect the absorptive and scattering processes within the hair fiber to impact luster. Finally, we make an attempt to study the effect of hair color on subjective evaluation of luster. An equation for perceived luster, taking into account the spectral sensitivity of the human eye is derived. Theoretical considerations show that the luster of hair of different colors is perceived differently by the human eye.

A new multifunctional, shine-enhancing emollient: PPG-3 benzyl ether myristate.

Abstract: A new emollient ester--Crodamol STS (INCI name: PPG-3 Benzyl Ether Myristate) has been developed and characterized. This special non-volatile emollient is safe to use and provides silicone-like feel and multiple cosmetic functionality. It is a liquid with a viscosity about 100 cps at room temperature. It has a high refractive index--1.4696, which enhances hair shine, contributes to high gloss in lip products, and reduces whitening effect of fatty alcohols and silica in anti-perspirants/deodorants applications. This emollient has high solubility of UV filters, low skin-spreading factor, and good pigment wetting behavior, which are preferable in sunscreen and make-up formulas to enhance the pigment localization and improve SPF value. In this paper, the chemical structure, physical properties, and various cosmetic applications of the emollient will be discussed. Especially, an objective hair shine (luster) test method (color image analysis) has been established and applied to study the enhancement in hair shine by Crodamol STS in hair spray and hair gel formulations. The objective measurements in hair shine showed good agreement with the results obtained from subjective evaluations. The substantivity of Crodamol STS on hair surface, which was delivered from a rinse-off cream, was also determined by a solvent extraction method.

Electron spectroscopy and microscopy applied to chemical and structural analysis of hair.

Abstract: The application of surface specific x-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) will be shown to be an effective means for the elucidation of hair fiber surface chemistry and structure. Examples studies of bleaching and fiber conditioning treatments are discussed. The bleached fiber surface is found to become more hydrophilic due to the loss of the naturally occurring hydrocarbon overlayer and oxidation of surface functional groups as a result of bleaching. Comparison between generic bleaching regimens illustrates the importance of increased pH and the presence of surfactant for effective treatment. Adsorption of conditioning diester quat and dimethicone molecules reintroduces a hydrophobic like surface layer on the hair fiber. Spectroscopic data indicates a segregated adsorption structure of the chemically difference conditioning molecules. Electron microscope Images of the conditioned hair shows a smooth uniform surface.

Effects of arginine on hair damage via oxidative coloring process.

Abstract: The purpose of this study was to measure the protective effects of arginine in oxidative coloring or bleaching process. Contact angle measurement, tensile measurement and amino acid analysis were employed. As the first step, it was shown that oxidative coloring or bleaching process decreases hair surface hydrophobicity and tensile strength in wet condition. Next the study has been conducted with coloring agents in which part of the ammonia was replaced with arginine, to find that arginine reduced the oxidative change in contact angle and tensile strength. These results suggest that arginine prevents the undesirable attack by hydrogen peroxide on hair proteins and hair surface lipids. Furthermore, it is also suggested from amino acid analysis that a considerable amount of arginine is deposited on, or in hair fibers from coloring agents.

Tensile properties of twisted hair fibers.

Abstract: Hair is routinely twisted during grooming processes, which can cause tangles and lead to breakage of hair fibers. To evaluate the damage caused by twisting hair, the tensile stress-strain properties of single twisted hair fibers were measured by two different experimental procedures: (A) twist at constant length, followed by extension to break (without untwisting); and (B) twist and untwist at constant length, followed by extension to break. In procedure (A), the strength, extension, and initial modulus decreased with increase in twist factor, whereas in procedure (B), the strength and extension did not significantly change from control values, although the initial modulus decreased with increase in twist factor. Furthermore, the degree of recovery from torsional deformation was studied by a variant of procedure (B), where the fiber after untwisting was relaxed for 5 and 10 minutes, respectively, prior to extension to break. The major conclusion from this study was that at low and moderate twist levels, the tensile mechanical properties of human hair are recoverable.

A study of the photolightening mechanism of red hair with visible and ultraviolet light: comparison with blond hair.

Abstract: The photolightening behavior of red hair was investigated. Red hair was found to lighten to a similar extent by irradiation from both ultraviolet (UV) and visible (VIS) light. Under the same irradiating conditions, blond hair was lightened by VIS light but did not lighten by UV light until it was washed after irradiation (1). These different photolightening behaviors of red and blond hair are supposed to be due to differences in their melanin compositions. The dominant type of melanin in red hair is pheomelanin; while blond hair investigated in the previous work contained both eumelanin and pheomelanin, with mainly eumelanin (2). Consequently, in this investigation, the photolightening behaviors of red and blond hair were compared to clarify the differences in photosensitivity between the two types of melanin.

Measurement and prevention of hair photoaging.

Abstract: Fluorescence spectroscopic measurement of the amino acid tryptophan on the hair fibre surface was extended to include in situ fibre irradiation and a novel cyclical wash off, reapplication protocol. When applied to the investigation of a new damage prevention active, it was shown that the active was preferentially degraded in a sacrificial manner and that the underlying fibre surface was maintained in good condition. In addition, tensile strength measurements were performed to assess the mechanical properties of the treated and untreated fibres following UV and sunlight exposure and the results demonstrate the damage prevention effectiveness of the active.

Protein loss quantification of abraded virgin and abraded bleached hair according to Bradford assay.

Abstract: This study intends to present Bradford assay as an alternative to Lowry test to quantify hair damage during combing or brushing. The protocol involves collecting hair fragments that are chipped away from hair during these abrasive treatments and quantitatively measuring the amount of protein using an analytical procedure to detect low amounts of proteins. This protein determination method involves the binding of Coomassie Brilliant Blue G-250 to hair protein (keratin). It is quite rapid and sensitive and less prone to interferences as the standard Lowry procedure. The latter is subject to interference from compounds such as lipids, cationic surfactants and EDTA, which are ingredients commonly used in hair care formulations and may lead to a false positive result. These drawbacks should be eliminated when using the so called Bradford method for hair protein quantitation. Our studies showed reproducible results for human hair protein and the developed color was stable for up to one hour. The data also show that virgin hair releases less protein than bleached hair. The amount detected for the former after combing ranges from 0.875 to 1.03 mg/g of hair and 4.85 to 5.35 mg/g of hair for the latter.

Spatial and angular distribution of light incident on coatings using Mie-scattering Monte Carlo simulations.

Abstract: We show the results of Mie-scattering Monte Carlo models developed to simulate the optical properties of light incident on particle-containing coatings. The model accommodates mixtures of particles with different sizes and complex refractive indices, enabling the simulation of formulations, including pigments. The simulation tracks trajectories of photons as they propagate through the turbid medium, calculating both angular and spatial light intensity distributions. Scalar quantities such as total transmission and reflection, and haze and diffuse reflectance, are also calculated.

Enhanced delivery of an anti-dandruff active in a shampoo vehicle.

Abstract: Formulating a delivery vehicle to enhance activity can potentially give higher activity or allow for adjustment to a lesser percent of active. A study was conducted in which the anti-dandruff active, Octopirox, INCI Piroctone Olamine [1-Hydroxy-4-methyl-6-(2,4,4-trimethylpentyl)-2(1H)-pyridinone], was incorporated into a simple shampoo base at two levels as well as in the same base with an added amphiphilic surfactant blend (Biobase SMC) at the lower level. A group of thirty (30) male subjects with moderate to severe dandruff were divided into three groups each of which evaluated one of three products for four weeks. Methods of evaluation included gravimetric determination of actual dandruff flakes, fluorescent staining of suspect yeast populations, blind evaluation by trained clinical personnel and panelist self assessment. The study demonstrated that the Octopirox at 0.2% active delivered in the amphiphile blend was superior to the same level in the simple shampoo base and equivalent in activity to a much higher level (0.5%) in the base only. A proposed mechanism postulates the formation of liposome-like association structures that solubilize and entrap the Octopirox and deposit is substantively to the scalp for enhanced longer lasting activity.

Evaluation of antioxidant properties of dermocosmetic creams by direct electrochemical measurements

Abstract: Cyclic voltammetry and linear sweep voltammetry were preliminarily used in order to evaluate the global antioxidant properties of dermocosmetic creams. Experiments were performed by introducing electrodes directly into the creams without any pretreatment of the samples. Current-potential curves showed significant anodic current depending on the antioxidant-containing cream studied. In comparison, little amperometric response was recorded with an antioxidant-free cream base. Aqueous solutions of the corresponding antioxidants showed analogous anodic waves and similar peak potentials. A correlation between the global anodic peak and the presence of the antioxidant species in the cream was made with eleven skin creams, attesting to the reliability of the method. Among the tested electrode materials, platinum gave the best results in terms of electrochemical kinetics and measurement precision (current peak standard deviation less than 5%). Exposure of a depilatory cream to oxidizing agents (e.g., hydrogen peroxide, air, or light) caused a decrease in peak current as expected. This methodology enabled us to evaluate the evolution of the total antioxidant capacity under oxidative stress and gives encouragement to further development of a voltammetric method to quantify cream antioxidant power.

A new long-chain UV absorber derived from 4-tert-butyl-4'-methoxydibenzoylmethane: absorbance stability under solar irradiation.

Abstract: A new UV filter, the 1-(4-tert-butylphenyl)-2-decanyl-3-(4'-methoxyphenyl)-propane 1,3-dione called C10-DBM, was prepared by grafting a ten-carbon aliphatic chain to the alpha-carbonyl position of 4- tert -butyl-4'-methoxydibenzoylmethane (BM-DBM).(1) UVA absorption efficiency of a cosmetic preparation containing this new filter, called C10-DBM, was tested and compared to an identical preparation containing BM-DBM. The two preparations were irradiated under a 150-W xenon lamp or exposed to natural sunlight. The originality of this new filter resided in that its UVA absorbance appeared during the irradiation of the molecule. Moreover, although the molar absorption coefficient of C10-DBM in the UVA domain was lower than that of BM-DBM, its absorption showed much more photostable behavior under both methods of irradiation. After two hours of sunlight exposure, the preparation containing the BM-DBM lost 85% of its UVA absorbance, whereas the UVA absorbance of the preparation containing C10-DBM showed a decrease of 3% in comparison to the maximum absorbance obtained after 30 minutes of irradiation. Also, after two hours of exposure to natural sunlight, the UVA absorbance of the preparation containing C10-DBM remained above its initial value (before the irradiation began).

Hair color changes caused by dyeing and thermal treatments.

Abstract: The aim of this study was to show the effect of heat exposure, dyeing, and shampooing on hair color as measured by diffuse reflectance spectrophotometry Successive dyeing of virgin hair with six permanent commercial formulations showed that color saturation was obtained after the first dyeing cycle An unexpectedly high difference in hair color saturation, measured as DE* values, was obtained for virgin hair samples that differed only in cleansing history After six sequential washings of the dyed hair samples, no difference was observed in color durability, indicating that the adhesion strength is similar to long-lasting and tone-up dyeing formulations Exposure to a hot plate at 172 degrees C showed a significant darkening of the virgin hair samples after 2 min On the other hand, virgin hair samples exposed to the gentler heat of a hand dryer (approximately 60 degrees C) showed partial disappearance of the hair medulla after 60 min However, values of total color difference were near the error limit

Use of triphenyltetrazolium chloride in preservative efficacy testing.

Abstract: Preservative efficacy testing without counting colonies was done by determining growth in dilutions of inoculated product following enrichment in Letheen broth with 0.001% triphenyltetrazolium chloride (TTC) in 96-well microtiter plates. Bacterial growth was indicated by the development of a red/pink color in the enrichment broth. The method was used to determine log reductions of bacteria at specified times after inoculation, and D-values were calculated using the reciprocal of the highest dilution showing growth (pink color) as the log CFU/ml bacteria at each time point. The method using TTC was validated by demonstrating that D-values for Staphylococcus aureus, Pseudomonas aeruginosa, Burkholderia cepacia, and Escherichia coli in 44 aqueous cosmetic and OTC-drug products were virtually identical to those obtained when using Alamar Blue in the miniaturized system. Plotting D-values obtained using TTC as a function of D-values obtained using Alamar Blue gave a line with a slope of 0.98, which shows excellent agreement of results obtained by the two methods. This miniaturized assay system has been used for more than three years for preservative efficacy testing of several hundred cosmetic and OTC-drug product samples in our laboratory. It is recommended for laboratories that conduct large numbers of preservative efficacy tests.

The application of polymethylene waxes as conditioning agent in hair relaxers.

Abstract: Hair relaxers are harsh chemical treatments that leave the hair dull, dry and limp. There is a constant need for improvement of these products to make them milder and incorporate conditioning properties. Because of the high pH of relaxer or hair straightening systems, most quaternized (conditioning) ingredients are unstable and slowly break down to release ammonia over time, having no conditioning effects by the time the consumers use them. This paper discusses the partial substitution of the fatty alcohols that are traditionally used in relaxer systems with polymethylene wax and the benefits derived from using them. The study included the investigation of synergies among the ingredients, the stabilities of the various systems and comparisons with commercially available systems. The polymethylene wax, used in combination with the mineral oil gel and phosphate salt, coats the hair during the relaxing process, leaving it shiny, soft and conditioned as opposed to the poor condition of the hair relaxed by traditional, commercially available NaOH and LiOH relaxers. An additional benefit of using polymethylene wax in relaxer systems is that the conditioning agents that are normally added to the neutralizing shampoo to repair or mask the damage as a result of the relaxing process can be omitted.