Comparative chemical and biological evaluation of Urtica dioica extracts obtained by methanol and hexane: antioxidant, cytotoxic, apoptotic, and antimicrobial potentials

BACKGROUND: Urtica dioica L. is a widely utilized medicinal plant with potential antioxidant, cytotoxic, and antimicrobial properties. METHODS: This study aimed to investigate its multi-target biological activities across four cell lines (A549, MDA-MB-231, HCT116, and BEAS-2B) while evaluating the impact of two extraction solvents (acidified methanol and hexane) on activity outcomes. RESULTS: The acidified methanolic extract exhibited higher total phenolic (61.25 ± 3.07 mg GAE/g) and flavonoid (51.20 ± 2.01 mg CE/g) content, correlating with superior antioxidant activity (DPPH: 84.36 ± 1.50 mg TE/g; CUPRAC: 174.04 ± 9.54 mg TE/g). In contrast, the hexane extract demonstrated stronger cytotoxicity across cancer cell lines (IC50: 3.10–4.12 µg/mL), along with significant induction of apoptosis and G0/G1 cell cycle arrest, despite lower antioxidant capacity. In addition, both extracts increased the protein levels of p21 and cleaved caspase-3, suggesting involvement of cell cycle inhibition and activation of intrinsic apoptotic signalling pathways. Moderate antimicrobial activity was also observed, with inhibition zones ranging from 7 to 10 mm across bacterial and fungal strains. CONCLUSIONS: These findings highlight the bioactive potential of U. dioica and the critical role of extraction solvent in modulating its total phenolic and flavonoid contents and biological effects. The observed upregulation of p21 and cleaved caspase-3 further supports the notion that U. dioica extracts may exert antiproliferative activity through p21-mediated cell cycle control and caspase-dependent apoptosis. Further in vivo studies and mechanistic investigations are needed to confirm these observations and clarify their potential therapeutic relevance.