Comparative evaluation of natural deep eutectic and conventional solvents for the extraction of bioactive compounds from saffron petals

Saffron petals, a major by‑product of Crocus sativus L., are rich in phenolic compounds, anthocyanins, and flavonoids but remain underutilized. This study systematically compared six conventional solvents (water, ethanol, water/ethanol 50:50, water/ethanol 20:80, water/methanol 50:50, and methanol) with five natural deep eutectic solvents (NADESs), ChCl: LA (1:1), ChCl: Gly (1:2), ChCl: Ox (1:1), Ox:S (1:2), and Ox: G (1:2), for their efficiency in extracting bioactive compounds from saffron petals. Extraction performance was evaluated using total monomeric anthocyanin content (TMAC), total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activity (DPPH assay). Among all systems, ChCl: LA exhibited the highest TMAC (11.63 mg/g), TPC (83.04 mg GAE/g), and antioxidant activity (90.29%), while ChCl: Gly showed comparable performance. Colorimetric analysis (CIE Lab*) and 2-month stability testing demonstrated superior pigment retention and physicochemical stability in NADES‑based extracts compared to conventional solvents. GC–MS profiling revealed distinct volatile compositions across solvent systems. Antimicrobial evaluation of all eleven extracts showed that NADES‑based systems, particularly ChCl: LA, exhibited stronger inhibitory effects against Escherichia coli and Staphylococcus aureus, whereas most conventional solvents displayed weak or negligible activity. Cytotoxicity assessment using 3T3‑L1 fibroblasts confirmed the biocompatibility of the ChCl: LA extract, with cell viability remaining above 80% across all tested concentrations. Overall, the findings highlight ChCl: LA as a food‑grade, biodegradable, and functionally robust solvent for efficient, stable, and biologically active extraction of saffron petal bioactives.