Human skin provides a home to the skin commensal bacteria. They live symbiotically on the skin in a variety of roles. Therefore, the study of skin commensal bacteria has become a new target in the field of cosmetics. There are many publications about unbeneficial bacteria such as Cutibacterium acnes and Staphylococcus aureus. Recently several studies have been reported on microvesicles (MVs) derived from commensal bacteria. These reports strongly suggest that MVs are very important for understanding the functional nature of skin commensal bacteria. In this study, we focused on the coagulase-negative staphylococci (CoNS), which is thought to be beneficial to skin, including Staphylococcus epidermidis. We evaluated the effects of MVs derived from CoNS (CNS-MVs) on human epidermal keratinocytes. We found that the CNS-MVs were incorporated into keratinocytes and promoted gene expression of cornified envelope formation factors. These results suggest that CoNS improves the barrier function of epidermal keratinocytes via MVs. S. aureus-derived MVs (SA-MVs) induced gene expression of TNFα as an inflammatory mediator on keratinocytes, while CNS-MVs showed little effect. These data strongly suggest that MVs of CoNS can be considered as a potential active component of microbiome based topical skin care ingredients which support skin barrier improvement.

Tactile evaluation is one of the important factors for the evaluation of skin conditions and the design of cosmetic formulation. Elucidation of the relationship between the tactile sense and the physical properties leads to useful knowledge for the development of cosmetics. In this study, we propose an approach that performs subjective evaluation of the tactile feeling and objective evaluation of the physical vibration at the same time. In this approach, we employed a wearable skin vibration sensor that detects vibration signals via a finger, and applied this sensor to the evaluation of the squeakiness feeling of washed skin. Firstly, we measured the vibration of various washed skin instances of the subjects by using the sensor wrapped around a subject's finger, and, at the same time, the subjective score of squeakiness feeling was obtained. Then, the acquired vibration signals were characterized with a time series analysis using time-delay coordinates. Finally, the relationship between the characterized signal features and squeakiness feeling was examined. As a result, it was shown that (1) the signal features derived from the stick-slip phenomenon relates to the squeakiness feeling, (2) the occurrence rate of the stick-slip phenomenon during skin rubbing and the subjective score of squeakiness feeling were correlated, and (3) there was diversity in interpreting skin vibrations as the squeakiness feeling. These results were obtained due to the advantages of the proposed approach, which suggests that the approach is useful for the tactile evaluation in the field of cosmetics.

Skin aging is a dermatologic change that affects appearance. It can increase with age or be promoted by exposure to ultraviolet (UV) radiation. Age-related skin changes can be divided into two types: intrinsic or chronological aging, and extrinsic or premature photo-aging, depending on physiological and environmental factors, respectively. Changes due to skin aging lead to atrophy and reduced hydration of the dermis. Applying olive oil to the skin may prevent premature aging owing to its effects, including moisturizing, antioxidant, and after-sun treatment. Here, we developed an innovative olive oil for attenuating age-related skin changes; it contains a special reddish pigment, shikonin, from the Lithospermum erythrorhizon root (LER), which has several properties that could prove beneficial for skin care. The aim of this study was to evaluate the potential benefits of the LER extract in olive oil for skin care, as the LER extract is an efficient antioxidant that contributes to the stability of olive oil. Shikonin in the LER extract was seen to be stable in olive oil, which could function as a UV and blue light absorber. The LER extract strongly inhibited the activity of dermal enzymes, such as collagenase and elastase. Moreover, the LER extract could attenuate oxidation and glycation stress. These results showed that olive oil containing LER extract possesses anti-skin-aging and anti-photo-aging activities. Using olive oil containing LER extract may be useful for attenuating age-related skin changes such as spots, wrinkles, and flabbiness and will help significantly improve skin health.

Hair damage generally increases from root to tip, and exogenous metals easily accumulate on damaged hair from such sources as water. There is a problem that the dyeing property of permanent hair color (oxidative hair dye) has an influence on the hair damage level. 2D elemental distributions and line profiles of the ultrastructure in cuticle layers were observed with a scanning transmission electron microscope equipped with energy dispersive X-ray spectrometry. It was confirmed that copper accumulated in the outermost A-layer and each endocuticle. Not only the cortex but also cuticle layers were dyed with permanent hair color. Hydrogen peroxide is contained in the permanent hair color as an oxidant, and its catalytic effect becomes stronger in the cuticle layers of the damaged part of the hair. As a result, it was considered that the dyeing property was also intensified in the damaged hair part due to the change of the reactivity of the oxidative dyes. It was also confirmed that copper in the outermost A-layer was reduced with chelating treatment, which suggests over-dyeing was suppressed.

Carbonyl protein (CP), which is produced in the stratum corneum (SC), the outermost layer of the skin, deteriorates SC functions such as water-holding capacity. In the SC, CP is formed by various oxidative stimuli including ultraviolet (UV) radiation. Carbonyl groups can be introduced into proteins via reactions with aldehydes, which could be decomposed from lipid peroxides. We previously established a novel experimental system mimicking stratum corneum carbonyl protein (SCCP) generation via UV-induced lipid oxidation occurring at the skin surface, which involves the induction of SCCP by UV irradiation in the presence of squalene (SQ) as an unsaturated lipid component in sebum. However, to date, no studies have focused on the suppression of SCCP generation by UV absorbers. Therefore, we here evaluated the protective efficacy of various UV absorbers against UV-induced SCCP generation with SQ considering their absorption properties. We found that either a UVB or a UVA absorber could suppress the induction of SCCP by UV in the presence of SQ. In addition, either a UVB or a UVA absorber suppressed the increase of the peroxide value of SQ by UV irradiation. This strongly suggests that UV absorbers can suppress SCCP induction at least in part via the reduced generation of peroxide. Interestingly, a combination of UVB and UVA absorbers, as well as a broad-spectrum UV absorber, exhibited remarkable efficacy in suppressing the increase of peroxide value of SQ by UV irradiation. These results suggest that a wide range of UV protection from UVB to UVA is essential to suppress SCCP induction. We evaluated the protective efficacy of various UV absorbers against SCCP induction by UV irradiation in the presence of SQ and found that both UVB protection and UVA protection are essential to prevent the generation of SCCP and to maintain healthy skin.

Assessing the quality of new product candidates in the mascara category has been done by asking consumers to try them and rate their overall performance. In addition to this overall rating, consumers answer specific questions about which performance-related characteristics of the product drive their preference. Understanding the relationship of these ratings to overall preference helps product researchers set priorities regarding which attributes to focus on as they plan future research. Our research group collaborated across internal evaluation divisions and with a research agency to field a large online survey in four countries that measured consumers' preferences for popular mascara products. The survey questionnaire was finalized in June 2016 with fieldwork conducted from late June through the following month of July. The products included were a mix of popular mascara brands sold in normal retail channels as well as department stores. Results were analyzed using the lavaan package in R to build a structural equation model (SEM) that explains the relationship between mascara preference and performance. The modeling results ranked the performance-related attributes by their influence on overall preference within the mascara products surveyed. As a result, researchers have prioritized the most impactful product attributes for improvement.

The aim of this study was to investigate the psychological and biological effects, such as brain activity, of tokimeki when participants were looking at pictures of cosmetics. Tokimeki is a unique Japanese word that describes positive feelings and is used to express excitement and elation when moved by something. Pictures of attractive cosmetics significantly increased tokimeki scores, decreased ‘discontent’, and increased ‘happiness’ compared to those of control cosmetics. A significant difference between oxy-Hb changes when viewing attractive cosmetics was recognized in channel 15, which corresponds to the left orbitofrontal cortex. Electroencephalography in the occipital area revealed that the increase of β/α ratio when viewing attractive pictures of cosmetics was higher than for the control. Partial least squares regression analysis suggested that tokimeki induces activation in the left prefrontal cortex and increases β/α ratio in the occipital region. Therefore, this study revealed the effects on emotions and brain activity of tokimeki for women caused by looking at cosmetic pictures from multiple perspectives. Thus, tokimeki can be considered a pleasant stimulus to our mind and brain, a so-called ‘happiness spice’ in daily life. This study is the first step towards predicting the degree of tokimeki from brain activity. In the future, we are going to study in detail what factors enhance tokimeki and we hope that further studies give many people a tokimeki feeling, and improve their quality of life.

For animal protection, various studies on alternatives to safety tests in animals are being conducted. The short-time exposure (STE) method is described in the Organization for Economic Cooperation and Development Test Guideline 491 as an alternative to eye irritation animal testing. However, its accuracy and labor investment can be improved if the results can be predicted before the experiment. This study evaluated whether Hansen solubility parameter (HSP) values can be used to predict STE results. An HSP sphere was created based on the HSP values and STE results of 48 substances. Substances inside and outside the sphere were designated as dangerous and safe substances, respectively. The safety of each test substance was predicted by comparing the center point (R₀) of the sphere with the relative energy difference, i.e., the ratio of each test substance (R_a). The accuracy, false-negativity, and false-positivity of the “irritant” and “non-irritant” designations, as determined by the STE results and Hansen sphere, were 91.7% (44/48), 4.8% (1/21), and 11.1% (3/27), respectively. These results indicate that HSP values can be used to predict STE results with high reproducibility, thereby evaluating the safety of the substances.