Prunus spinosa L. Branches as a New Source of Condensed Tannins: Phytochemical Profile and Antioxidant, Cytotoxic and Genotoxic In Vitro Evaluation

(1) Background: <i>Prunus spinosa</i> L. is known for its polyphenolic profile, including condensed tannins, compounds associated with various biological activities, including antiproliferative effects. Its woody biomass, such as branches, remains largely underexplored, as a few studies have investigated its potential bioactive content. This study aimed to characterize and evaluate the biological potential of crude extract (PS) obtained from <i>P. spinosa</i> branches. (2) Methods: The extract (PS) was prepared using microwave-assisted extraction (MAE) under optimized green conditions (70% ethanol, 1/10 solid-liquid ratio, 5 min, 600 W). Its chemical profile was analyzed by High-Performance Thin-Layer Chromatography (HPTLC). Antioxidant capacity was assessed through HPTLC-DPPH, DPPH and ABTS assays. In vitro cytotoxicity and genotoxicity were evaluated on HeLa (tumoral) and Vero (normal) cell lines using MTT and Comet assays. (3) Results: HPTLC analysis revealed the presence of condensed tannins. The extract demonstrated potent radical scavenging activity (IC₅₀ 1.02 ± 0.25 mg/mL), dose-dependent cytotoxicity, and higher sensitivity of HeLa cells. Genotoxic effects were significantly more pronounced in tumor cells than in normal ones. (4) Conclusions: These findings highlight the condensed tannins' phytochemical profile, antioxidant and selective antitumor properties of PS, supporting its valorization as a sustainable source of multifunctional bioactive compounds.