Green solvent-based extraction of Annona muricata L. (soursop) leaves: Influence on physicochemical properties, phytochemical content, and antioxidant activity

Annona muricata L. (soursop) leaves are recognised as valuable sources of phenolic compounds with strong antioxidant potential, although conventional solvent extraction often provides limited selectivity and inadequate recovery of key bioactive constituents. Natural deep eutectic solvents (NADES) represent a greener extraction alternative, yet their performance in recovering phenolics, flavonoids, rutin, and antioxidant components from A. muricata leaf extract (AMLE) remains insufficiently explored. This study evaluated four NADES formulations, namely choline chloride–lactic acid (ChCl–LA), citric acid–L-proline (CA–LP), betaine–lactic acid (B–LA), and choline chloride–glycerol (ChCl–G), in comparison with water using ultrasound-assisted extraction. Physicochemical properties of the solvents, including pH and viscosity, were determined prior to extraction to elucidate their influence on solvent–solute interactions and extraction behaviour. Extraction efficiency was assessed through rutin content, total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activities measured by DPPH, ABTS, and FRAP assays. All NADES systems exhibited acidic pH (۱.۸۰–۴.۹۷) and substantially higher viscosity than water, with ChCl–LA combining strong acidity and comparatively low viscosity, favourable for mass transfer. ChCl–LA demonstrated the strongest extraction of targeted bioactive constituents, achieving ۱۶۴.۱۶ ± ۲.۳۴ mg GAE/g TPC, ۱۶.۵۵ ± ۰.۵۲ mg QE/g TFC, ۰.۷۹۶ ± ۰.۰۲۳ mg/g rutin, and consistently high antioxidant activities across all assays. Correlation analysis indicated that FRAP activity was strongly associated with TPC, while DPPH and ABTS activities showed stronger associations with rutin and TFC, highlighting the contribution of different phenolic subclasses to antioxidant responses. The results demonstrate that solvent physicochemical properties, particularly acidity and viscosity, play a critical role in governing bioactive selectivity and antioxidant performance. ChCl–LA was identified as the most effective green solvent for producing antioxidant-rich AMLE suitable for development of functional foods and nutraceutical products.

کلیدواژه ها:

Annona muricata ، NADES ، Ultrasound-assisted extraction ، Rutin ، Antioxidant