J. Cosmet. Sci., 65, 69–79 (March/April 2014) 69 Antioxidant, antimelanogenic, and skin-protective effect of sesamol MONTRA SRISAYAM, NATTHIDA WEERAPREEYAKUL, SAHAPAT BARUSRUX, and KWANJAI KANOKMEDHAKUL, Graduate School, Faculty of Pharmaceutical Sciences, Khon Kaen University, Khon Kaen, 40002, Thailand (M.S.), Center for Research and Development of Herbal Health Products, Khon Kaen University, Khon Kaen, 40002, Thailand (N.W.), Faculty of Pharmaceutical Sciences, Khon Kaen University, Khon Kaen, 40002, Thailand (N.W.), Centre for Research and Development of Medical Diagnostic Laboratories, Khon Kaen University, Khon Kaen, 40002, Thailand (S.B.), Faculty of Associate Medical Sciences, Khon Kaen University, Khon Kaen, 40002, Thailand (S.B.), Faculty of Sciences, Khon Kaen University, Khon Kaen, 40002, Thailand (K.K.) Accepted for publication February 18, 2014. Synopsis Sesame contains high nutritional value and important bioactive lignans which are good for health-promoting effects including sesamol. Sesamol is found in trace amounts in sesame. The biological action from the trace amounts of sesamol found might indicate its effi cacy. This paper presents a systematic study of the antimela- nogenic and skin-protective effects (antioxidant) of sesamol and positive compounds. The results showed that sesamol had the most scavenging 2,2-Diphenyl-1-picrylhydrazyl hydrate (DPPH·) radical with an IC50 value 14.48 μM. The antioxidant power (Ferric reducing antioxidant power value) of sesamol at a concentration of 0.1129 μM was 189.88 ± 17.56 μM FeSO4. Sesamol inhibited lipid peroxidation with an IC50 value of 6.15 ± 0.2 μM. Moreover, sesamol possessed a whitening effect by inhibition of mushroom tyrosinase at an IC50 value of 1.6 μM and an inhibition of cellular tyrosinase with 23.55 ± 8.25% inhibition at a concentra- tion of 217.2 μM. Sesamol exhibited high antioxidant and anti-tyrosinase activity compared to the positive control, kojic acid and β-arbutin. Sesamol from edible sesame seed could therefore have an alternative cosme- ceutical purpose. INTRODUCTION Sesame is rich in proteins, dietary fi ber, micronutrients, and bioactive phytochemicals. The seeds and their pressed oil contain important bioactive lignans sesamin, sesamolin, and sesamol. The presence of sesame lignans were reported to play a pivotal role in Address all correspondence to Natthida Weerapreeyakul at natthida@kku.ac.th.

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.