The sales appeals and consumer needs or the technical development and trends of research area for cosmetics are changing with the times. Consumer needs, among them, involves two kinds of waves in trends : the strong demand for effects and functions, or “Functionalism” and the demand for natural, safe and secure materials, or “Naturalism.” The movement of these waves was switched around the year 2000. Functionalism indicates an orientation similar to the digital spirit (masculine brain) shown in the trend in overall consumption behavior. From the same point of view, Naturalism resembles the analog spirit (feminine brain). Cosmetics should have value in comfort and safety in use as well as effectiveness as its basic function. Yet, at the same time, cosmetics should seize the trend of consumers' demands and should always ride on the tide of time.

View full abstract

18-MEA (18-Methyleicosanic acid) is an unusual branched-chain fatty acid covalently bound to the cuticle surface of hair. 18-MEA makes the surface hydrophobic and acts as a boundary lubricant to decrease frictional resistance. It can be easily removed in alkaline conditions such as hair color or perm, and the surface becomes hydrophilic and friction increases. This is one of the phenomena of hair damage. Focusing on the recovery of 18-MEA on hair surface, we found a persistent 18-MEA layer can be generated on the surface of hair by the use of a specific tertiary amine. The combination of 18-MEA with the specific tertiary amine (Stearoxypropyldimethylamine : SPDA) makes the bleached hair surface hydrophobic, and its hydrophobicity is maintained even after shampooing. Characterization of adsorbed layers of 18-MEA/SPDA on a mica surface, as a possible hydrophilic surface model, was performed using Atomic Force Microscopy (AFM) and Angle-resolved X-ray Photoelectron Spectroscopy (AR-XPS).The results revealed that 18-MEA/SPDA formed a layer with high wear resistance, with an alkyl chain, the hydrophobic moiety, oriented at an angle of around 35°to the air interface and the anteiso-branch moiety of 18-MEA providing higher fluidity to the upper part of the layer. Sensory evaluation of this technology was also performed and it was recognized that 18-MEA/SPDA could provide not only a silky, smooth and moisturized texture but also the right amount of body/bounce and less frizz and flyaway.

View full abstract

A link between psychosocial stress and acne has long been postulated, but its mechanism is not yet clear. Cortisol, the main glucocorticoid (GC) in humans, is considered a stress hormone. It is well known that GC treatment provokes an acneiform reaction. Toll-like receptor 2 (TLR2) activation by Propionibacterium acnes (P. acnes) may induce skin inflammation via induction of various proinflammatory molecules. In this study, we examined the effects of GC on TLR2 expression in cultured human keratinocytes (HK) to elucidate a relationship between stress and acne. The addition of GC to HK markedly enhanced their TLR2 gene expression, which was further stimulated by P. acnes, TNF-α or IL-1α. Moreover, Melia azadirachta extract had potent inhibitory activity against TLR2 expression induced by GC and TNF-α. These findings suggest that GC-enhanced TLR2 expression plays an important role in the exacerbation of acne. Moreover, Melia azadirachta extract may be useful to prevent inflammation of stress-induced acne.

View full abstract

Reactive oxygen species (ROS), generated by ultraviolet radiation or diverse oxidative stress, are believed to promote aging. Various methods for evaluation of antioxidant activity have been proposed. In particular, the methods using cultured cells are thought to be capable of evaluating antioxidant activity in a way similar to in vivo conditions. In this study, we investigated a method which reflected the intracellular antioxidant activity more precisely than the conventional method, by introducing a novel ROS detection reagent, 5-(and-6)-chloromethyl-2', 7-dichlorodihydrofluorescein diacetate (CM-H₂DCFDA), which permeates cell membranes better and is retained longer within the cells, normal human dermal fibroblast (NHDF), than conventional reagents. Cellular antioxidant activity (CAA) values for representative polyphenols, caffeic acid, quercetin and EGCg were measured by the investigated method. As a result, CAA values for caffeic acid (100μM), quercetin (50μM) and EGCg (50μM) were 82, 48, and 68% respectively, and it was supposed that the intracellular antioxidant activity, including the penetration amount of samples into the cells, was evaluated more precisely.

View full abstract

Skin tension, “hari”, is one of the factors of ideal skin. “Hari” is often considered to be a mechanical property such as skin elasticity and most researchers have focused on the dermis to improve it. However, we hypothesized that“ hari" has a visual factor in addition to a tactile one and thus we focused on it in this study. By cluster analysis using data of sensory evaluation on Japanese female facial skin, we found that apparent “hari" was very close to apparent moistness, while it were classified under a different cluster from tactile “hari”. Apparent “hari” correlated with both water contents of the stratum corneum and transepidermal water loss. Because these results suggest that the improvement of the water conditions of the stratum corneum may lead to enhancing apparent “hari”, we applied moisturizing products for female facial skin to investigate whether the scores of apparent “hari” improved when the stratum corneum water conditions were improved. As a result, water contents of the stratum corneum and apparent “hari” were both significantly improved, while there was not a significant change in tactile “hari”. Our results suggest that apparent “hari” and tactile “hari” each have their own approaches suitable to improving their properties.

View full abstract

Skin color unevenness, such as age spots, freckles and acne, accounts for the majority of skin trouble in Japanese females, and has been becoming an important research subject in the field of both cosmetics and beauty healthcare. We analyzed the melanin unevenness in the faces of 201 Japanese females in their teens to 70s using independent component analysis, which can separate an original color image into a melanin component image and a hemoglobin component image. As a result, we discovered that thin and vague border melanin unevenness, which differs from age spots, spreads into the skins. We also found out that the age change of “vague border melanin unevenness” became more conspicuous in the cheeks, and spread over the facial skin from upper cheek to lower cheek with aging. Furthermore, we found a high correlation between “vague border melanin unevenness” and “skin dullness”, which is a skin trouble specific to middle-aged females. From the above findings, we conclude that “vague border melanin unevenness” is appropriate as the new evaluation index of “skin dullness”, and is useful for the effectiveness evaluation of whitening products.

View full abstract