Spectrophotometric Evaluation of the Sun Protection Factor of Wild Sideritis raeseri Extracts under Different Solvent and Temperature Conditions

Plant-origin sunscreen products for skin protection from ultraviolet radiation are preferred over synthetic products as safer with regard to possible toxicity, allergies, and are eco-friendly. This study fills a gap in peer review research for endemic Albanian wild mountain tea (Sideritis raeseri Boiss & Heldr.) for its ultraviolet photoprotective properties under various solvent types, incubation days, and temperatures, by utilizing the Mansur method. S. raeseri aqueous extracts were centrifuged, filtered, and then mixed in two Erlenmeyer flasks: one with distilled water and the other with ethanol in a 1:4 v/v ratio. Absorbance measurements within the 290-320 nm range were taken at different temperatures over six consecutive days.  Neither water nor ethanol absorbs within this range. In extracts at room temperature (29-31 °C), Sun Protection Factor (SPF) value expressed as mean ± standard deviation dropped from 26.426 ± 0.2 on day one to 17.930 ± 0.19 on day six; for refrigerated extracts at 11 °C, SPF dropped from 26.426 ± 0.2 to 22.469 ± 0.19. In the water-ethanolic mixture at room temperature, SPF dropped from 23.281 ± 0.21 to 13.387 ± 0.036, and with refrigeration, from 23.281 ± 0.21 to 21.199 ± 0.21. At refrigerated conditions, the SPF of S. raeseri extract was photochemically more stable and showed a longer shelf-life, while SPF values at room temperature incubation were lower. Higher SPF values were found in water solutions than water-ethanol. The refrigerated water-ethanol mixture could be utilized in sunscreen products as a stability factor for SPF values of S. raeseri extracts.