A proposal of a standardized protocol to evaluate waterproof effect of eyeliner and mascara.

Objective: Eye make-up products must have waterproofing properties to make sure that their colours do not smudge or wash away easily and remain intact despite water or perspiration. Until now, most research has focused on composition and components of make-up products and not on the level of waterproof. This study aimed to find methods to assess the waterproof degree of eyeliners and mascaras and determine the suitability of these methods.

Effects of resveratrol, oxyresveratrol, and their acetylated derivatives on cellular melanogenesis.

Resveratrol and oxyresveratrol are naturally occurring phenolic compounds with various bioactivities, but their uses in cosmetics have been partly limited by their chemical instabilities. This study was performed to examine the anti-melanogenic effects of the acetylated derivatives from resveratrol and oxyresveratrol. Resveratrol and oxyresveratrol were chemically modified to triacetyl resveratrol and tetraacetyl oxyresveratrol, respectively.

Isolation of resveratrol from vitis viniferae caulis and its potent inhibition of human tyrosinase.

Tyrosinase (TYR) catalyzes rate-limiting reactions of cellular melanin synthesis, and its inhibitors are of commercial interest as potential skin whitening agents. However, the limited availability of human TYR makes the screening of TYR inhibitors difficult. To overcome this hurdle, we transformed nonmelanocytic human embryonic kidney (HEK) 293 cells to express human TYR constitutively.

Screening of plant extracts for human tyrosinase inhibiting effects.

Screening for tyrosinase (TYR) inhibitors potentially useful for control of skin pigmentation has been hampered by the limited availability of human TYR. To overcome this hurdle, we have established human embryonic kidney (HEK293)-TYR cells that constitutively express human TYR. In the current study, we assayed human TYR inhibition activities of 50 plant extracts using the lysates of transformed HEK293-TYR cells.

Use of non-melanocytic HEK293 cells stably expressing human tyrosinase for the screening of anti-melanogenic agents.

Tyrosinase (TYR) from mushrooms has been inappropriately used in the screening assay for hypopigmenting agents even though its biochemical properties are different from those of human TYR. Cell-free extracts of human epidermal melanocyes (HEMs) could be another choice for the assay, but HEMs grow too slowly to get a sufficient amount of cell-free extracts. In the present study, human embryonic kidney (HEK) 293 cells were transfected with a human TYR construct to establish a cell line that grows rapidly and expresses human TYR constitutively.

Comparison of the antimelanogenic effects of p-coumaric acid and its methyl ester and their skin permeabilities.

Background: p-Coumaric acid (PCA) inhibits human tyrosinase (TYR) activity and melanin synthesis in human epidermal melanocytes.

Objective: The purpose of the current study was to examine the potential of PCA and its hydrophobic derivative, methyl p-coumarate (MPC), as hypopigmenting agents for topical use.

Methods: PCA and MPC were comparatively tested against in vitro human TYR enzyme activity and cellular melanin synthesis in human epidermal melanocytes.

Detection of low levels of nitric oxide using an electrochemical sensor.

Nitric oxide produced from nitric oxide synthases mediates various physiological and pathological events in biological systems. However, quantitative assessment of nitric oxide from biological sources remains a difficult task. Here we describe a procedure for the quantification of low levels of nitric oxide using a nitric oxide - selective electrochemical sensor.

p-coumaric acid not only inhibits human tyrosinase activity in vitro but also melanogenesis in cells exposed to UVB.

Tyrosinase (TYR) catalyzes rate-limiting steps of melanogenesis and thus its inhibitors are potentially useful as hypopigmenting agents. Recently, p-coumaric acid (p-CA) has been suggested to interfere with the pro-melanogenic actions of tyrosine due to its structural similarity with tyrosine (An SM et al., Br J Dermatol 2008.

Evidence for the association of peroxidases with the antioxidant effect of p-coumaric acid in endothelial cells exposed to high glucose plus arachidonic acid.

Although many plant-derived phenolic compounds display antioxidant effects in biological systems, their mechanism of action remains controversial. In this study, the mechanism by which p-coumaric acid (p-CA) performs its antioxidant action was investigated in bovine aortic endothelial cells under oxidative stress due to high levels of glucose (HG) and arachidonic acid (AA), a free fatty acid. p-CA prevented lipid peroxidation and cell death due to HG+AA without affecting the production of reactive oxygen species.

Differential gene expression in young and senescent endothelial cells under static and laminar shear stress conditions.

Laminar shear stress (LSS) caused by blood flow is known to regulate endothelial function and to contribute to vascular health. By way of contrast, endothelial cell senescence seems to increase the incidence of vascular disorders. In an attempt to identify genes associated with vascular health/disease states, this study assessed the differential gene expression of young and senescent human umbilical vein endothelial cells (HUVECs) under static and LSS conditions.

Inhibition of melanogenesis by tyrosinase siRNA in human melanocytes.

Tyrosinase (TYR) plays a critical role in cellular melanogenesis and, thus, has been the major target of pharmacological approaches for the control of skin pigmentation. This study examined an alternative molecular approach using TYR-small interfering RNA (siRNA) to control melanogenesis in the human melanocytes. Both the mRNA and protein levels of TYR were significantly lowered by TYR-siRNA treatment, whereas TYR-related protein 1 and TYR-related protein 2 displayed no such changes.

p-Coumaric acid, a constituent of Sasa quelpaertensis Nakai, inhibits cellular melanogenesis stimulated by alpha-melanocyte stimulating hormone.

Background: Recent study has demonstrated that Sasa quelpaertensis (Korean name, Jeju-Joritdae) extracts inhibit cellular melanogenesis implicating potential use in the control of skin pigmentation.

Objectives: The purpose of the present study was to elucidate the active constituents of this plant inhibiting melanogenesis and the associated mechanism.

Methods: The effect of the plant-derived materials on melanin production and/or tyrosinase expression was examined in murine melanoma B16/F10 cells and neonatal human melanocytes.