J. Cosmet. Sci., 61, 133–145 (March/April 2010) 133 Comparison of hydration, tyrosinase resistance, and antioxidant activation in three kinds of pearl powders DONG-ZI SHAO, CHENG-KUN WANG, HANN-JANG HWANG, CHING-HSIA HUNG, and YU-WEN CHEN, Department of Cosmetics Application and Management, Chung Hwa University of Medical Technology, 89 Wenhwa 1st St., Tainan, Taiwan 717 (D.-Z.S., H.-J.H.), E-Chyun Dermatology Clinic, No.70, Sec. 3, Jhonghua E. Rd., East District, Tainan City, Taiwan 701 (C.-K.W.), Department of Physical Therapy, National Cheng Kung University, Tainan, Taiwan (C.-H.H.), and Department of Physical Therapy, China Medical University, Taichung, Taiwan (Y.-W.C.). Accepted for publication August 24, 2009. Synopsis In recent years, people have bred freshwater pearls as a substitute for natural pearls that occur in seawater, and they have also developed water-soluble pearl powder (P-w) and ultra-micro (P-μ) and ultra-nano pearl pow- der (P-n) products. However, neither the scientifi c value of pearl powder, nor the differences in effi ciencies of different pearl powder products is still unknown. In this study, the effectiveness of three kinds of pearl pow- der products in various applications was compared. Tests for transepidermal water loss (TEWL) and evalua- tions of the skin surface hydration of test subjects showed that pearl powder has a satisfactory moisturizing effect on skin and that P-μ has a distinctly stronger moisturizing effect than P-w. The three pearl powder products can also signifi cantly reduce the activation of tyrosinase and free radicals. In tests for reducing power and 1,1-diphenyl-2-picrylhydrazyl (DPPH) for scavenging free radicals, P-n and P-μ showed better perfor- mance than P-w. These results provide a reliable scientifi c basis for the use of pearl powder in beauty treat- ment, resistance to aging, and clinical medical treatment. INTRODUCTION In accordance with volume 46 of the Compendium of Materia Medica by Li Shizhen of the Ming Dynasty (1578 AD), “applying the pearl to the face can make the skin moisturized and glossy…comfort the mind and eliminate the poxes and the toxicity.” In the Encyclo- pedic Dictionary of Chinese Medicine Xie Guan et al. wrote in 1921: “The pearl can pacify people and brighten the eyes if applied to the face, it can make the skin moisturized and glossy.” For more than 2000 years, pearls have been used in China, and their value in beauty treatment and medicine has been often recognized. Since ancient times, the pearl Address all correspondence to Dong-Zi Shao.
JOURNAL OF COSMETIC SCIENCE 134 has been the favorite choice of the “imperial family” for beauty treatment and health care, and still, people consider the pearl as a symbol of beauty, youth, and eternity, and have great esteem for it. Pearl powders ground from natural pearls are considered pure products and are used for beauty treatment and health care (internal or external). They are rich in nutrients and mainly contain the following ingredients: calcium carbonate (CaCO3), proteins stimulat- ing cell regeneration, nearly 20 kinds of amino acids, some trace elements (1,2), and conchiolin. Conchiolin is the general designation for organic substances contained in shells and pearls, and they endow pearls with their beauty and health-care effi cacy (3). In 1905, Mikimoto Kokichi, from Japan, called the “father of pearl breeding,” was the fi rst to successfully breed a pearl in seawater. In 1940, when “outer membrane nucleus insertion technology” was developed (4), freshwater pearl-breeding industries emerged at a tremendous pace. In 1968, nucleus insertion technology was promoted and improved, providing favorable conditions for the development of freshwater pearl-breeding indus- tries. Before its use, water-soluble pearl powder (P-w) receives biotechnical treatment. In gen- eral, acid (most frequently lactic acid) or enzyme is used to turn the CaCO3, which is insoluble, into soluble calcium lactate in pearl powders. Insoluble components are dis- carded, and the water-soluble products are obtained through recrystallization. As these products are soluble, they are conveniently absorbed both internally and externally by the human body. Compared with traditional pearl powders, nano pearl powder is ground to microscopic dimensions. These molecules are small, which enables high-effi ciency absorption. Evaporation of moisture from human skin mainly proceeds through noninductive evapo- rating excretion, sweating, and external factors. Noninductive evaporating excretion is mainly through epidermal water loss (i.e., transepidermal water loss [TEWL]). TEWL measures skin barrier function high loss of water from the skin implies lower stratum corneum water-holding capacity. Using moisturizing cosmetics, the water-holding ca- pacity of the stratum corneum can be improved, and loss of water from the skin itself can be reduced. The hydration state of the skin is used to evaluate the water content of the skin surface and the water-holding capacity of the skin. In the epidermis, pigmentation is due to an excess of melanin. Tyrosinase is a rate-limit- ing enzyme used for the ultimate formation of melanin. Therefore, it is possible for tyro- sinase depressors to reverse abnormal pigments and to be used as a skin whitener (5). Reactive oxygen species (ROS), such as superoxide anion, hydroxyl radicals, and hydro- gen peroxide, are chemically reactive molecules derived from oxygen. They are by-prod- ucts produced in living organisms through many metabolic pathways. Formation of excessive free radicals in the human body can damage proteins, lipids, cell membranes, nucleic acids, and cells. Damage produced by free radicals can accumulate in the human body, which may cause aging, cancers, cardiovascular disease, Alzheimer’s disease, and Parkinson’s disease. Natural antioxidants in the daily diet can bind to unstable free radi- cals in the human body and protect the body from the damage caused by active oxygen as well as by oxidation due to other free radicals (6,7). Consequently, antioxidants that can neutralize direct ROS attacks and terminate free radical-mediated oxidative reactions would have benefi ts in protecting the human body from such diseases (8).
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