Optimizing the Extraction of the Polyphenolic Fraction from Defatted Strawberry Seeds for Tiliroside Isolation Using Accelerated Solvent Extraction Combined with a Box-Behnken Design.

Tiliroside is a natural polyphenolic compound with a wide range of biological activity, and defatted strawberry seeds are its rich source. The goal of this study was to optimize accelerated solvent extraction (ASE) conditions, including temperature, solvent composition, and the number of extraction cycles, using Box-Behnken design to maximize the yield of tiliroside. UPLC-DAD-MS was applied to investigate the polyphenolic composition of the extracts, and preparative liquid chromatography (pLC) was used for isolation. All obtained mathematical models generally showed an increase in the efficiency of isolating polyphenolic compounds with an increase in temperature, ethanol content, and the number of extraction cycles. The optimal established ASE conditions for tiliroside were as follows: a temperature of 65 °C, 63% ethanol in water, and four extraction cycles. This allowed for the obtainment of a tiliroside-rich fraction, and the recovery of isolated tiliroside from plant material reached 243.2 mg from 100 g. Our study showed that ASE ensures the isolation of a tiliroside-rich fraction with high effectiveness. Furthermore, defatted strawberry seeds proved to be a convenient source of tiliroside because the matrix of accompanying components is relatively poor, which facilitates separation.

Protective Effect of Urtica dioica Extract against Oxidative Stress in Human Skin Fibroblasts.

Urtica dioica is a species with well-established significance in folk medicine in many countries. It was utilized to support the treatment of arthritis, allergies, and urinary tract disorders; however, the substantial presence of antioxidants suggests that nettle extract could also have a positive impact on the skin. The objective of this study was to assess the impact of nettle extract on human skin fibroblasts subjected to oxidative stress. Various solvents were tested to prepare an extract rich in polyphenolic compounds with high antioxidant potential. The chemical composition was determined using ultra-high-performance liquid chromatography with mass spectrometry (UPLC-DAD-MS). H2O2 treatment was used to induce oxidative stress and cell viability, and the metabolism was evaluated through NR and MTT assays. Our study demonstrated that extraction with 80% ethanol, followed by the drying and re-dissolving of the extract in pure water, was more efficient than direct extraction with water. This yielded an extract rich in polyphenolic compounds, with chlorogenic acid and caffeoylmalic acid as the predominant compounds, averaging 64.9 and 114.4 µg/mL, respectively. The extract exhibited antioxidant properties in the DPPH and ABTS assays. Furthermore, it did not exhibit cytotoxicity and did not negatively affect cell metabolism. In addition, it effectively reduced ROS in the H2O2-stimulated cells, and at the highest concentration tested, the ROS levels returned to those of the untreated control. The extract also protected against H2O2-induced cytotoxicity. The cell viability was maintained at the level of the untreated control when the cells were pretreated with the extract before H2O2 exposure. These findings indicate that U. dioica extract is a valuable and safe additive in skincare products.