The SPF determination of Albanian mountain tea Sideritis raeseri subsp. raeseri and correlation with phenolic compounds

¹ University of Tirana, Faculty of Natural Sciences, Department of Physics, Tirana, Albania
² Polytechnic University of Tirana, Faculty of Mathematical and Physical Engineering, Department of Physics, Tirana, Albania

^* Author to whom all correspondence should be addressed: This email address is being protected from spambots. You need JavaScript enabled to view it. ; https://orcid.org/0000-0002-3098-3488

Published online: 15 April 2026

Abstract

This study used the Mansur et al. method to determine the Sun Protection Factor (SPF) for the Sideritis raeseri subsp. raeseri plant (wild-growing mountain tea) and its related compounds. To achieve this, 1 gram of the plant and 1 gram of its different aerial parts (leaves, flowers, and stem) were weighed on an analytical scale and divided into separate empty beakers. By pouring 50 ml of boiled distilled water in each beaker and mixing it for 5' with 1g of dried aerial parts, water-distilled tea aqueous extracts were prepared for each group, followed by filtering and centrifuging. The optical density (O.D.) values were measured for each 20%v/v solution of plant leaves, stem, and flower (5%v/v). The mean O.D. values of three measurements (performed with a UV-VIS spectrophotometer model 756s, using distilled water as a blank reference) at wavelengths between 290 and 320 nm (with 5 nm intervals) were used to calculate the SPF in vitro using the Mansur et al. formula. Results showed that the leaf extract had the highest SPF (43.17), followed by the flower extract (13.14) and the stem extract (4.92). The SPF of the entire plant was recorded as 13.14. These findings indicate that the plant, particularly its leaves, possesses significant sun protection potential and could be suitable for use in cosmetics. The SPF values of the aerial parts were directly proportional to their phenolic content, with a strong positive correlation confirmed by Pearson's correlation coefficient (r = 0.958, p < 0.01).