Development of Ultrasound-Assisted Synthesis of Natural Acidic Deep Eutectic Solvents (NADESs) for Extraction of Bioactive Compounds from Agrifood Wastes Valorization: Antioxidant and Antiradical Scavenging Elucidation

Natural acidic deep eutectic solvents (NADESs)-ultrasound-assisted technique was developed and used to valorize agrifood waste. The extraction capacity of the synthesized NADESs was comprehensively evaluated using the peels of African nutmeg. The antioxidant and antiradical scavenging properties of the extracts were investigated using various in vitro methods. The extraction process was studied using many factors at a time (MFAT) experimental design and further optimized through a rotatable central composite design response surface methodology (RCCDRSM). The effects of different operating conditions were evaluated comprehensively to determine the parameters necessary for antioxidant recovery in terms of TPC and TFC, and antiradical scavenging activity based on CUPRAC and FRAP methods. The conditions that gave the highest values of 908.17 µgGAE/g DW, 1431.51 µgQE/g DW, 11.5568 µMTE/g DW, and 14.7903 µMTE/g DW for TPC, TFC, CUPRAC, and FRAP were found in CaFr12, CaGc11, CaFr11, CaXy11 as solvents respectively. These results underscore the potential of using specific NADES formulations to tailor the extraction process for desired antioxidant and antiradical scavenging properties. The findings give insights into the capacity of NADESs as powerful solvents for extraction applications, and further optimized. Four independent factors of temperature, time, volume, and concentration, determined from the MFAT studies which significantly affected bioactive molecule extraction were optimized to elucidate the best conditions that produce the maximum TPC extracts, maximum TFC extracts, and maximum antiradical scavenging activity through CUPRAC, FRAP, and DPPH inhibition. The optimized conditions with maximum desirability for TPC, TFC, CUPRAC, FRAP, and DPPH were temperature, time, volume, and concentration of 45ºc, 5 min, 25 ml, & 90%; 30ºc, 5min, 25 ml, & 90%; 30ºc, 5 min, 25 ml, % 90%; 45ºc, 25 min, 25 ml, & 50%; and 50ºc, 15 min, 15 ml, & 70%, respectively. CaFr11 was observed to be the best-performing solvent among the NADESs studied as it outperforms others by extracting the highest TPC, and TFC as well as the highest CUPRAC antiradical scavenging activity at the optimized conditions. CaSu11 had the highest FRAP power, while CaXy12 gave the highest DPPH inhibition at optimized conditions. Besides, all the studied NADESs outperformed water, the greenest solvent, in TPC, and TFC extraction, as well as in DPPH inhibition. However, water extracts performed better than CaGC21, CaGl11, and CaGl21 in FRAP tests. The results are like findings obtained by other researchers who performed optimization of UAE-Choline chloride NADESs extraction using other plant materials. This study demonstrated the feasibility and effectiveness of using ultrasound-assisted synthesis of natural acidic deep eutectic solvents (NADESs) for the extraction of bioactive compounds from agrifood wastes. The combination of NADESs and UAE not only provided higher yields of antioxidants but also offered a sustainable, green alternative to conventional solvents. The antioxidant and antiradical scavenging assays confirmed the potential of these extracts for applications in the food, pharmaceutical, and cosmetic industries. The findings highlight the role of NADESs in enhancing extraction processes and valorizing agrifood wastes, paving the way for further research on the scalability and commercial viability of this approach.