Detection of UV Induced Free Radicals in Hair and their Prevention by Hair Care Products

present study is aimed to quantify the protection factor of UV filters and antioxidant containing hair care products. Most of the techniques used to define oxidative damage to hair structures are focused on the macromolecular hair structure properties. Table 1 lists some of the most widely used endpoints to measure oxidative damage and UV protection in hair care. Color is perhaps the most obvious characteristic of human hair. The color of hair is due to the presence in the cortex of granules of a pigment called melanin. Biopolymers from the melanin family of molecules are known to be semiconducting and photoconductive. These materials are heteropolymers of indolequinones such as 5,6-dihydroxyindole (Fig. 1). Biologically, the melanins perform a variety of roles. Predominantly, they are photoprotectants and pigments, but it is thought that they also function as antioxidants, free radical scavengers, and charge transport mediators. S olar UV exposure is one of the most important factors that leads to photoageing and photodamage of the hair. The melanin pigment in the hair protects from UV-induced free radicals, since melanins are efficient radical scavengers. The amount of UV induced free radials can be quantified by measuring the melanin radicals. The new Radical Hair Protection Factor (RHF) presented in this paper allows to characterize the protection effect of hair care products containing UV filters and/or antioxidants. Abstract to three categories: (a) mechanical (i.e. brushing, friction); (b) chemical (i.e. perms, oxidative colouring, lipid-depleting surfactants); and (c) environmental (i.e. solar radiation, heat from hot blow drying, chlorine from swimming pools) (1,2). Solar exposure and oxidative coloring are the most common and important factors that can lead to color fading and loss in hair manageability, caused by alteration of the hair surface. The hair encounters more damage as it becomes more hydrophilic, the cuticles of the hair surface are lifted and the hair shows more split ends (3-5). In fact, ultraviolet (UV) radiation is cosidered to be the most damaging of all environmental factors. Hair has natural protection against the sun’s rays. UV rays cause major changes in the mechanical ultra-structural and sensorial properties of hair, such as change of texture, a dry appearance, increase in porosity, loss of suppleness, ecc. (6). UV rays also effect the color and brillance of hair. The UV induced damage involves deep changes in the structure of keratin caused by the photo-oxidation of amino acids, sterols and fatty acids, resulting in rupture of sulfur bridges, decomposition of lipids, decrease in melanin as well as numerous micro-molecular lesions (7,8). In conclusion, oxidative damage is the main reason for hair condition changes and the most important contributor to oxidation is UV radiation. Oxidative reactions in biological systems lead to the generation of free radicals. An efficent approach to alleviate the damage is the use of UV filters and antioxidants able to reduce the amount of free radicals. The Introduction