JOURNAL OF COSMETIC SCIENCE 70 health-promoting effects. Sesamol is a phenolic compound that is metabolized from sesa- molin by heat/hydrolysis and is mainly found in roasted sesame or in processed sesame oil (1). Sesamol is—by comparison with other active compounds such as sesamin and sesamo- lin—only a trace component whether it is found in the seed, roasted sesame oil, roasted sesame meal, or sesame lignin extract (1,2). Intensive studies of sesamol indicate that sesamol not only possesses a phytochemical value but also medicinal effects. Sesamol acts as a metabolic regulator possesses chemopreventive, antioxidant, anti-lipid peroxidation, antimutagenic, antihepatotoxic (3), antibacterial, antifungal (4), anti-MMP-9 (5), anti- infl ammatory activities (6) and prevents neurodegenerative diseases associated with aging such as Alzheimer’s disease and stroke (3). In this study, we evaluated the potential of sesamol for an alternative use as a cosmeceutical. Ultraviolet ray (UVR) plays an important role in skin aging as it initiates the generation of reactive oxygen species (ROS) that induce oxidative stress. Different types of UV ra- diation have different mechanisms of cell toxicity. The oxidative stress of skin will lead to the depletion of endogenous antioxidants both intra- and intercellular, enhancement of intracellular lipid peroxidation, and the induction of specifi c signal transduction path- ways that modulate inflammatory, immunosuppressive, or apoptotic processes in the skin (7). Although skin possesses antioxidant systems, the free radicals were excessively gener- ated by UV radiation hence antioxidant defense is overwhelmed leading to skin damage at the cellular level. Oxidative stress causes destruction of the protein collagen, changes cellular renewal cycle, damages DNA, and promotes the release of proinfl ammatory me- diators (cytokines) that trigger infl ammatory skin disease. Moreover, the free radicals further undergo the pathogenesis of allergic reaction in the skin (8). The destruction at the dermis that contains collagen, fi brils, and elastin could affect the strength and fl exi- bility of the skin. When disarrangement of the skin occurs, problems such as wrinkling and aging arise. These factors lead to increasing deterioration in skin texture, complex- ion, and function. Therefore, there is an urgent need for an effective antioxidant to protect the skin from the UV-induced damage. In addition, the exogenous antioxidants that can scavenge ROS and improve the antioxidant/pro-oxidant balance may benefi t the skin. The ROS generated can further activate melanocyte to produce more melanin pigment leading to pigmentary disorders such as melasma (9). Melasma is a hyperpigmentation disorder, and although there is no pain, it has a signifi cant impact on the quality of life. Melasma is worsened by UV exposure and hormonal factors. A crucial part of prevention is photoprotection and avoidance of inducing factors (e.g., such as ROS, UV exposure, and hormonal factor) (10). Treatment of melasma is associated with the topical hypopig- menting agents like hydroquinone, tretinoin, and azelaic acid and its derivatives (11). Various studies attempted to fi nd practical antioxidant and antimelanogenic compounds for skin application. A number of tyrosinase inhibitors have been reported from both natural and synthetic sources, but only a few of them are used as skin-whitening agents, primarily due to safety concerns. Among the skin-whitening agents, hydroquinone is one of the most widely prescribed (12,13). Notwithstanding, hydroquinone is considered to be a potent melanocyte cytotoxic agent which can induce mutations (14,15) conse- quently, the discovery of safe herbal or pharmaceutical depigmentation alternatives is needed. To confi rm the multifunctional effect of sesamol, this study investigated its potential antimelanogenic and skin-protective effects vis-à-vis its antioxidant properties and tyrosi- nase inhibition in the human melanoma (SK-MEL2) cell line.

WHITENING AND ANTIAGING EFFECT OF SESAMOL 71 MATERIALS AND METHODS CHEMICALS Sesamol was purchased from Spectrum Chemical (Gardena, CA) α-Tocopherol from Fluka Biochemika (Buchs, Switzerland) butylated hydroxy anisole (BHA) and butylated hydroxy toluene (BHT) from Fluka AG (Buchs, Switzerland) 2,2-Diphenyl-1-picrylhydrazyl hydrate (DPPH•) from Fluka (Buchs, Switzerland) 2,4,6-Tri(2-pyridyl)-1,3,5-Triazine (TPTZ) was from Tokyo Kasei Kogyo Co., Ltd. (Tokyo, Japan) thiobarbituric acid from Sigma-Aldrich chemie GmbH (Buchs, Switzerland) linoleic acid from Sigma-Aldrich chemie GmbH (Steinheim, Germany) dimethyl sulfoxide (DMSO) from Sigma (St Quentin Fallavier, France) ferric chloride (FeCl3.6H2O) and ferrous sulfate (FeSO4.7H2O) from Asia Pacifi c Specialty Chemical Limited (Seven Hills, Australia) mushroom tyrosinase, β-arbutin, and neutral red (NR) from Sigma–Aldrich Chemical Co. (St. Louis, MO) kojic acid from TCI (Tokyo, Japan) L-3,4-dihydroxyphenylalanine (L-DOPA) from Acros Organic Geel (Geel, Belgium) and, DMEM medium, fetal bovine serum (FBS), and penicillin/streptomycin from GIBCO (Grand Island, NY). The UV spectra were recorded on UV–Vis spectrophotometry from Shimadzu, UV-1700 PharmaSpec (Kyoto, Japan), while the microplate reader was from Anthos 2010 (Anthos Labtec Instruments, GmbH, Salzburg, Austria). DETERMINATION OF DPPH· RADIC AL SCAVENGING ACTIVITY The effect of sesamol on radical scavenging by DPPH was determined in comparison to three standard compounds—viz., BHA, BHT, and α-tocopherol. Various concentrations of test compounds in methanol were added to a methanolic solution of the DPPH radical. The fi nal concentration of DPPH was 0.02 mM. The mixture was shaken thoroughly and kept in the dark at room temperature for 30 min. The absorbance of the resulting solu- tion was measured by UV–Vis spectrophotometry at 520 nm (16). DETERMINATION OF FERRIC REDUCING ANTIOXIDANT POWER (FRAP) The FRAP assay was assessed according to Benzie and Strain (17). The method was based on the reduction of the Fe3+-TPTZ complex to the ferrous form (Fe2+) at low pH. This reduction was monitored by measuring the change of absorbance at 600 nm, which was related to the combined or “total” reducing power of the existence of electron-donating antioxidants in the reaction mixture. Briefl y, 50 μl of working FRAP reagent prepared daily was mixed with 200 μl of diluted test compounds. The stock solutions of the test compounds were dissolved in the DMSO. The absorbance at 600 nm was recorded after 8 min incubation at 37°C. FRAP values were obtained from the difference of absorptions in the reaction mixture with those from increasing concentrations of Fe3+ and were expressed as μmol of Fe2+. The standard curve was linear between 15.625 and 250 μM FeSO4 with R2 = 0.9603. DETERMINATION OF INHIBITION OF LIPID PEROXIDATION (LPO) USING THE THIOBARBITURIC ACID REACTIVE SUBSTANCES (TBARS) ASSAY LPO was measured in terms of TBARS according to the reaction with malondialdehyde equivalents formed from the peroxidation of lipids as described by Bae and Lee (18).