1 Laboratorio de Fotoquímica, Centro de Química, Instituto Venezolano de Investigaciones Científicas - IVIC
The present study evaluated the photostability of Rubus niveus fruit using a solar simulator. Since degradation under solar irradiation is a key indicator of stability capacity, photostability assays are fundamental to evaluating the preponderance of R. niveus extract for biological applications involving light. Additionally, the quenching and scavenging capacity against different types of free radicals was assessed. Ethanolic extracts were prepared from frozen black raspberries. Quenching and scavenging activity were measured using a series of analytical procedures. These included UV-Vis spectroscopic analysis, photostability assessment using solar radiation spectrum (with solar simulator), chemiluminescence, and DPPH assays. Reactions with singlet oxygen (¹O₂) and galvinoxyl radical were also employed to evaluate scavenging capacity. The results revealed that R. niveus is a source of anthocyanins (128.68±0.85 mg/lt and 48.19±0.31 mg/100 g of fresh weight) and exhibits remarkable photostability under solar light, with minimal degradation at its absorption wavelength. Its photostability was comparable to that of common sunscreen filters (Neo Heliopan Type Ma and Neo Heliopan Type OS). Furthermore, a noteworthy antioxidant capacity was demonstrated, effectively reducing reactive oxygen species (ROS) and free radicals, with significant scavenging activity comparable to that of vitamin C in some assays. Particularly, the extract displayed superior scavenging activity against highly reactive hydroxyl radicals compared to vitamin C (86.82% vs. 55.13%). These results suggest that the ethanolic extract of R. niveus is photostable and has the capacity to scavenge and neutralize different types of dark- and light-induced reactive oxygen species. Further in vitro and in vivo research is recommended to validate the potential of R. niveus compounds as natural ingredients in cosmetic and nutraceutical products.