The adsorption behaviour and photoprotection effect of UV filter absorbed on the surface of human hair.

Abstract

Butyl methoxydibenzoylmethane (BMBM, an UVA absorber, the maximum absorptive wavelength is about 360 nm), octylmethoxycinnamate (OMC, an UVB filter, the maximum absorptive wavelength is about 310 nm), benzophenone-3 (an UVA and UVB filter, the maximum absorptive wavelength is about 288 and 323 nm) and octyl salicylate (an UVB filter, the maximum absorptive wavelength is about 307 nm) are four types of UV filters. This report presents the adsorption behaviours and effects of these filters on hair cuticles. Adsorption amounts of each UV filter on the hair surface were determined via the depletion method, and the photoprotective effects of these filters were identified by various methods, including protein degradation, tryptophan degradation and lipid peroxidation in hair exposed to irradiation. Results showed that adsorption of UV filters occurred fairly rapidly and reached equilibrium after approximately 1 h. The rate and amount of adsorption increased with increasing initial concentration. The adsorption amount of each UV filter was plotted against its equilibrium concentration. The adsorption capacity of 2% BMBM was higher than that of the other UV filters. Lipid peroxidation and protein degradation of hair were significantly reduced in samples treated with benzophenone-3, octyl salicylate and OMC. Tryptophan degradation was not significantly improved in any of the treatments. The adsorption kinetics of the filters is comparable with a pseudo-second-order kinetic model and that their adsorption isotherms match the Freundlich adsorption model. Adsorption followed an endothermic process. UV filters have effect on protecting hair from photodamage. The effect of UVB filters is better than UVA filters.