Eco-friendly extraction of polysaccharides from Moringa oleifera Lam. leaves using COSMO-RS screened natural deep eutectic solvents

This study aimed to develop a straightforward and efficient method for screening natural deep eutectic solvent (NADES) with high extraction yield of polysaccharides from Moringa oleifera Lam. ( M. oleifera ) leaves and to elucidate the solubilization mechanism of this eco-friendly extraction solvent. Traditional extraction methods are often limited by low efficiency, long processing times, and environmental hazards, which hinder the advancement of polysaccharide applications. In this study, the conductor-like screening model for realistic solvents (COSMO-RS) was adopted to prognosticate the solubility of biomolecules, and the M. oleifera polysaccharide (MOLP) solubility of 32 NADESs was appraised. Based on the solubility and activity coefficient results, we meticulously selected eight highly efficient NADESs combinations and conducted practical verification. The Bet-LA (Betaine- Lactic acid) combination demonstrated the highest extraction efficiency for MOLP, achieving an ultrasonic-assisted extraction rate 2.67-fold higher than that of the conventional ethanol solvent. The dissolution mechanism was further elucidated using frontier molecular orbital (FMO) and reduced density gradient (RDG) analyses. Antioxidant assays demonstrated that polysaccharides extracted by Bet-LA exhibited superior biological activity. These findings establish an efficient NADES screening protocol and provide mechanistic insights for optimizing M. oleifera leaves polysaccharide extraction.