Taeko Mizutani

Anti-photoaging capability of antioxidant extract from Camellia japonica leaf

It is well known that the Camellia japonica leaf exhibits antioxidant activity because of its high content of polyphenolic compounds. Thus, the extract prepared from mature leaves of C. japonica (CJML) has been widely used as an anti‐ageing material in foods and cosmetics. Concerning the process of growing C. japonica, it is expected that the extract from green leaves (CJGL) has superior effects compared with that from mature leaves. However, there are few reports that discuss the difference between green and mature leaves. In this study, both CJML and CJGL were extracted with 50% 1,3‐butylene glycol (1,3‐BG) and used for investigations. In a chemical examination, we compared both extracts in terms of scavenging activities against hydrogen peroxide (H2O2) and hydroxyl radicals. CJGL exhibited higher scavenging activities against both types of ROSs compared with CJML. In addition, CJGL reduced the carbonylation of tape‐stripped stratum corneum (SC) after UVB irradiation. In a biological study, the intra‐cellular ROS level of HaCaT keratinocytes precultured with CJGL for 24 h was significantly lower than that of the control cells. Furthermore, cell damage induced by H2O2 exposure was attenuated by 24 h precultivation with CJGL but not by 2 h precultivation. The results of examinations indicate that CJGL possess properties that reduce oxidative stress. In addition, the result of 2 h precultivation with CJGL suggests that CJGL might affect the status of intra‐cellular antioxidants.

Carbonylated proteins exposed to UVA and to blue light generate reactive oxygen species through a type I photosensitizing reaction

BACKGROUND Carbonylated proteins (CPs) are generated by the reaction of basic amino acid residues in proteins with aldehyde compounds produced during lipid peroxidation. CPs in the stratum corneum (SC) impact skin conditions such as skin moisture functions including water content and transepidermal water loss (TEWL). In addition, CPs can be frequently seen in the SC from sun-exposed sites compared with sun-protected sites. OBJECTIVE The aim of this study was to reveal whether CPs could be a generation source of reactive oxygen species (ROS) in the SC following exposure to ultraviolet (UV) radiation and to identify the type of ROS and its generation mechanism. METHODS ROS generation was detected using a methyl cypridina luciferin analog (MCLA) chemiluminescence system and an ESR spin-trapping method. CPs in porcine SC, in a keratin film and in bovine serum albumin (BSA) were prepared by reaction with acrolein. Levels of protein carbonylation were quantified by detecting aldehyde residues. RESULTS CP levels in the SC were increased in a UVA energy-dependent manner. That result suggested that a source of ROS generation existed in the SC initiated and produced the carbonylation of SC proteins. Carbonylated BSA and carbonylated porcine SC sheets exhibited fluorescence spectra at an excitation wavelength of 430nm and an emission wavelength of 520nm. Irradiation of the SC with UVA increased protein carbonylation and the amount of autofluorescence in the SC. ROS generation in the SC caused by UVA and by short-wavelength visible light (blue light, 400-470nm) was detected by the MCLA chemiluminescence system. Artificially carbonylated porcine SCs and keratin films had increases of chemiluminescence intensity after exposure to both light sources as well. The addition of superoxide dismutase to the MCLA system completely abolished the incremental chemiluminescence intensity after both UVA and blue light exposure of the SC. In addition, acrolein-treated BSA gave ESR signals like hydroxyl radicals (OH) converted from superoxide anion radicals (O2-) during irradiation with a xenon arc lamp containing UVA and visible light. From the sum of these results, we consider that CPs are produced from O2- initially generated from exposure to UVA and blue light. CONCLUSION CPs are excited by absorbing sunlight, particularly UVA and blue light, and result in the generation of O2- through a CPs progress new protein carbonylation in stratum corneum through ROS generation. photosensitizing reaction. Further, the results suggest that the O2- produces CPs in the SC through lipid peroxidation in the sebum, and finally affects skin conditions including color and moisture functions.

Topical treatment with sacran, a sulfated polysaccharide from Aphanothece sacrum, improves corneocyte‐derived parameters

Sacran, a polysaccharide isolated from Aphanothece sacrum (Suizenji‐nori) alga, has unique characteristics in terms of its physiological properties and effects on the skin, and has recently become a focus of attention as a novel biomaterial. In a previous study, we reported the unique physical characteristics of sacran, which forms a gel‐like film containing water in the presence of polyols. This film resists penetration by water and chemicals. We expected this unique physical characteristic to act as an artificial barrier upon the application of sacran to the skin. In the present study, we tested the efficacy of sacran application in healthy individuals who reported previous symptoms of dry or inflamed skin, to evaluate the potential benefits of sacran for skin care in patients with mild atopic dermatitis. Compared with placebo, sacran‐containing serum did not significantly alter either the water content of the skin surface or transepidermal water loss. However, subjects using the serum showed improvements in corneocyte parameters including size, percentage of thick abrasion, ratio of SH to SS groups, ratio of interleukin (IL)‐1 receptor antagonist to IL‐1α, and carbonylated protein level. These results indicate that the sulfated polysaccharide sacran is an effective agent for improving or maintaining the skin conditions.

A red pumpkin seed extract reduces melanosome transfer to keratinocytes by activation of Nrf2 signaling

The induction of skin pigmentation by ultraviolet (UV) radiation has been shown to result from factors secreted from UV‐exposed keratinocytes that enhance melanogenesis in melanosomes (MSs) and stimulates their transfer to keratinocytes. Among those factors, it has been reported that α‐melanocyte stimulating hormone, which is converted from the precursor proopiomelanocortin (POMC) following UV exposure, stimulates the transfer of MSs from melanocytes to surrounding keratinocytes.

Correlations between skin hydration parameters and corneocyte-derived parameters to characterize skin conditions

Skin hydration is generally assessed using the parameters of skin surface water content (SWC) and trans‐epidermal water loss (TEWL). To date, few studies have characterized skin conditions using correlations between skin hydration parameters and corneocyte parameters.

Defensive Effects of a Unique Polysaccharide, Sacran, to Protect Keratinocytes against Extracellular Stimuli and Its Possible Mechanism of Action

Sacran, a polysaccharide isolated from the alga Aphanothece sacrum (Suizenji-nori), has unique physical and physiological characteristics. In a previous study, we reported that sacran improves skin conditions in individuals who suffer from atopic dermatitis (AD), focusing on its trapping function against extrinsic stimuli compared with hyaluronic acid (HA). First, we examined the penetration of sacran through stratum corneum (SC) with an impaired barrier function using immature reconstructed human epidermal equivalents. Sacran penetrates the SC to living cell layers of the epidermis, which suggested that sacran would attenuate adverse influences in keratinocytes caused by extracellular factors such as irritants or proinflammatory cytokines such as interleukin 1α (IL-1α). Sacran markedly reduced the cell damage induced by a nonionic detergent, sodium lauryl sulfate (SLS). Moreover, sacran restored the elevation of intracellular reactive oxygen species (ROS) levels stimulated by SLS and by IL-1α. These effects of sacran were superior to those of HA. In order to investigate the restoration effects of sacran, the influence of sacran on the physical properties of lipid bilayers was evaluated by measuring the order parameter using the ESR spin-labeling method. Because sacran failed to cause changes in the order parameters of liposomes and HaCaT keratinocytes, these results indicate that sacran does not interact with lipid bilayers although it restored changes in the order parameter caused by SLS. The sum of these results demonstrates that sacran reduces the influence of extracellular stimuli by its trapping effects. We conclude that the improving action of sacran is based on its trapping effect.