Ultrasound-assisted extraction with natural deep eutectic solvent for phenolic compounds recovery from Rosa damascene Mill.: Experimental design optimization using central composite design

Combining natural deep eutectic solvents (NADES) and ultrasonic-assisted extraction (UAE) created a green extraction medium for important phenolic compounds recovery from Rosa damascene Mill. For this purpose, three different NADES based on lactic acid were designed and tested as green extraction solvents. Citric acid, glucose, mannitol, and glycerol were used as hydrogen bond donors (HBD), while lactic acid as a hydrogen bond acceptor (HBA). The best extraction efficiency was demonstrated by NADESLACAGLY, which contains lactic acid, citric acid, and glycerol (3:1:2) compare with two other NADES (NADESLAGLU and NADESLAMA) and conventional solvents (ethanol and methanol). These parameters included total phenolic compounds (TPC), total flavonoid compounds (TFC), and antioxidant activity (AA). Then the UAE procedure was optimized through response surface methodology (RSM) using central composite design (CCD). Quadratic models produced a satisfactory fitting of the experimental data with regard to total phenolic compounds (R2 = 0.9625, p < 0.0001 and p < 0.05), total flavonoid compounds (R2 = 0.9682, p < 0.0001 and p < 0.05), and antioxidant activity (R2 = 0.9940, p < 0.0001 and p<0.05). An extraction time of 60 min, a solvent volume of 35 mL, and an amount of water in NADES 30 % (v/v) were considered optimal conditions. The present study demonstrates the potential for creating eco-friendly solvents with enhanced extraction capabilities compared to organic solvents for the extraction of bioactive compounds from various natural sources that are used as natural food colorants and cosmetic dyes.