WILD PLUM IN COSMETIC FORMULATIONS 281 FLUORESCENCE OF SKIN Fluorescence is observed when light is absorbed at one wavelength and then emitted at a longer wavelength. The glow associated with healthy and young skin results from the fl uorescence of skin. Typical wavelengths that are associated with young skin are the blue- light wavelengths of 390 nm for elastin and desmosine and 378 nm for collagen (5,7,8). In vivo fl uorescence methods (5,14) of normal versus sun-exposed skin demonstrate a dramatic decrease in blue and green fl uorescence, believed to be caused by UV light from the sun that inhibits cellular repair (15) and results in injury to skin connective tissue, thus causing a reduction in collagen and elastin (Figure 1) (7,16). Older skin and photo- damaged skin that has been exposed to sunlight over time shows a dramatic decrease in fl uorescence emission in the blue and green region of the electromagnetic spectrum. This paper presents the application of a new optical brightening agent named Wild Plum that improves the luster and visual appearance of skin. Wild Plum compensates for the reduced blue fl uorescence of aged skin, thereby neutral- izing imperfections and leaving a natural, luminous appearance. We formulated Wild Plum with talcum powder in order to take advantage of the “soft focus effect” (17,18) that also improves skin appearance by exploiting the diffuse refl ectance of light. METHODS AND PROCEDURES FORMULATION OF FOUNDATION, POWDERS, BLUSHES, CREAMS, ETC. The formulation was designed to achieve a subtle luminescent glow of the product. Com- mercial foundation or loose powder was formulated with Wild Plum using a procedure developed at Novel Chemical Solutions (4,19). The formulated products were characterized Figure 1. Fluorescence emission of sun-exposed skin (forehead) and non-sun-exposed skin (buttocks) dem- onstrating the dramatic decrease of elastin, desmosine, and collagen fl uorescence after sun exposure (at λem = 278 nm, 390 nm, and shoulder at 429 nm). The fl uorescence of the skin was induced by a helium-cadmium laser and collected via a fi beroptic probe. (Reprinted with permission from the American Medical Associa- tion, Archives of Dermatology, 1988, 124, 1514–1518).
JOURNAL OF COSMETIC SCIENCE 282 by UV-Vis spectroscopy (Varian Cary 100 UV-visible spectrophotometer), fl uorescence spectroscopy (RF-5301PC Shimadzu spectrofl uorophotometer), and particle size analysis (Mastersizer X and Hitachi S3000 scanning electron microscope). CHARACTERIZATION OF WILD PLUM Particle size Analysis. The particle size was measured with a Hitachi S3000 scanning elec- tron microscope and a Mastersizer X from Malvern Instruments in order to determine if Wild Plum has appropriate granularity for cosmetic applications. UV-Vis. Visible spectroscopy was performed to determine the absorbance profi le of Wild Plum. A 4.78 × 10−8 M solution of Wild Plum in DMSO was prepared. The sample was placed in a quartz cuvette and measured using a Varian Cary 100 UV-visible spectro- photometer. Fluorescence. A 4.78 × 10−9 M solution of Wild Plum in DMSO was prepared for solution fl uorescence in order to determine if blue fl uorescence emission was achieved in medium- to-high intensity. For solid-state fl uorescence, Wild Plum was mixed with talcum pow- der and placed in a 1-mm quartz cuvette. The cuvette was placed into the sample holder at a 45° angle to the incident beam. The sample was measured using a Shimadzu RF- 5301PC spectrofl uorophotometer (λex = 364 nm). Quantum yield. The quantum yield of Wild Plum was measured by the protocol of Jobin Yvon (Horiba), using 9,10-diphenylanthracene and quinine sulfate as quantum yield standards (20). IN VIVO TESTING OF WILD PLUM The female model was photographed with a Panasonic DMC-TC1 digital camera under fl uorescent offi ce light without makeup, with makeup, and with makeup that was formu- lated with Wild Plum. L*, a*, and b* values were determined using Adobe Photoshop CS2. This procedure was performed 15 times for each photo, each time selecting color from a different place on the picture and then averaging. Sampling regions were matched between different images. EXPERIMENTAL RESULTS WILD PLUM FLUORESCENCE Absorption of light energy excites molecules in these colored materials to their excited states. Fluorescence has occurred when relaxation of these excited states takes place via radiative decay, resulting in emission of light at a longer wavelength than that of the absorbed light. Unlike many other optical brighteners that are active only to ultraviolet light, Wild Plum particles are optically active to visible light and alter the perceived appearance of the skin by emitting favorable light. As seen in Figure 2, this report dem- onstrates that Wild Plum has a photoluminescence of blue light, with the emission centered between 400 nm and 500 nm (λmax = 450 nm). Wild Plum has a fl uorescence quantum yield
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