A UV Spectroscopic Study of the Photoprotective Properties of Troxerutin, Ferulic Acid, and Aqueous Extracts of Melissa officinalis and Mentha piperita

Both natural and manmade components are used as photoprotective means in cosmetics. In this work, the photoprotective properties of aqueous extracts of Melissa officinalis and Mentha piperita and of aqueous solutions of troxerutin and ferulic acid were studied by UV spectroscopy. The photoprotective performance of these substances was evaluated by such parameters as the sun protection factor SPFin vitro, critical wavelength λcrit, and ratio of the areas under the absorbance curve in the ranges 320–400 and 290–320 nm (UV-A/UV-B). The resistance of the substances to the UV radiation was also evaluated. The study revealed certain photoprotective properties of aqueous extracts of Melissa officinalis and Mentha piperita. The extract obtained from Melissa officinalis and treated to remove ballast substances showed the highest SPFin vitro value. However, the absorption properties of the vegetable extracts decrease in the course of prolonged UV irradiation simulating the solar irradiation. Troxerutin absorbs UV light mainly in the range 320–400 nm, is resistant to UV radiation and atmospheric oxygen in aqueous solutions, and can be used as a UV-A filter in cosmetic formulations. Ferulic acid absorbs UV radiation mainly in the wavelength range 280–320 nm, but under the action of UV radiation the absorption properties of a ferulic acid solution change significantly. The UV spectrum of ferulic acid also changes under the action of atmospheric oxygen.