Eco friendly deep eutectic solvent based extraction of Raphanus sativus leaf bioactives with mechanistic and antibacterial evaluation

Deep eutectic solvents (DESs) have emerged as sustainable alternatives to conventional organic solvents for bioactive recovery. In this study, five DESs-Pro-Gly, Bet-Gly, ChCl-OA, ChCl-Gly, and CC-Gly-were synthesized and screened for their ability to extract phenolics and flavonoids from Raphanus sativus (Radish) leaves. Among them, Pro-Gly exhibited the highest efficiency, yielding 14 mg GAE/g DW of phenolics. Extraction was further optimized using ultrasound-assisted extraction, where cavitation-driven cell wall disruption enhanced solvent penetration and mass transfer. Response Surface Methodology (RSM) with a Central Composite Design (CCD) identified water content in DES as the most influential factor, while the Extreme Gradient Boosting (XGBOOST) model provided accurate predictive capability with mean errors below 14%. Fourier-transform infrared (FTIR) analysis of the Pro-Gly extract confirmed hydroxyl, carbonyl, and aromatic functional groups, indicating successful recovery and stabilization of phenolics and flavonoids through solvent-solute interactions. The extract displayed strong antioxidant capacity and notable antibacterial activity, particularly against Gram-positive strains, with inhibition zones comparable to ampicillin. These findings demonstrate the dual role of DESs as green solvents and functional enhancers, highlighting their potential applications in food preservation, nutraceuticals, and pharmaceutical formulations.