Comparative Effect of Extraction Techniques on the Phenolic Content and Antioxidant and Antigenotoxic Activities of Rubus saxatilis L.

Rubus saxatilis L. (Rosaceae) is used in traditional medicine in Central Kazakhstan, yet the effect of the extraction method on its phenolic profile and biological activity has not been studied systematically. Three extracts were compared: two prepared by ultrasound-assisted extraction differing only in solvent—water (WE) and 50% ethanol (UAE)—and one by microwave-assisted extraction with 50% ethanol (MAE), allowing the effect of solvent (WE vs. UAE) and of extraction technique (UAE vs. MAE) to be assessed separately. Phenolic composition was determined by HPLC-UV-ESI-MS; antioxidant activity in vitro; cytotoxicity for Artemia salina; and antigenotoxic effects using Escherichia coli K12 MG1655 lux-biosensors (pKatG::lux, pSoxS::lux, pColD::lux) and Drosophila melanogaster models. Four phenolics were identified, with gallic acid dominant in the UAE and MAE extracts and hyperoside predominant in WE, while rutin was not detected in WE. MAE showed the strongest radical-scavenging activity (DPPH, IC50 = 7.44 µg/mL), whereas WE had the highest reducing power (FRAP, EC50 = 52.97 µg/mL). All extracts were non-toxic for A. salina and induced neither oxidative stress nor the SOS response; instead, they attenuated dioxidine-induced SOS signalling by up to 57%, suggesting an antigenotoxic (DNA-protective) effect at the bacterial level. In Drosophila, extracts produced moderate extract-dependent genotoxicity: the lowest damage was observed for MAE. The extraction method governs the phenolic profile and biological activity of R. saxatilis, with MAE being most favorable.