RSM-based optimization of microwave- and ultrasound-assisted green extraction of iron-chelating and antioxidant natural products from Azadirachta indica leaves

Azadirachta indica is an abundantly available plant and known for its medicinal properties. Some studies showed its iron chelating activity (ICA) with possible implications for iron overload disorders. The present study aimed to discover efficient and green methods for obtaining ICA-rich extract from A. indica leaves. Microwave-assisted extraction (MAE) and ultrasound-assisted extraction (UAE) methods were optimized using response surface methodology (RSM). Four-factor Box-Behnken designs were used (with 29 runs) with five response factors for each technique. Aqueous choline chloride-glycerol (CCG) DES was employed as an extractant. ICA, total phenolic content (TPC), total flavonoid content (TFC), radical scavenging activity (RSA), and ferric-reducing antioxidant power (FRAP) were the responses. The optimal conditions discovered for MAE were 30 mL/g solvent-to-solid ratio (SSR), 38 % DES concentration, 330 W power and 15 s time with predicted ICA, TPC, TFC, FRAP, and RSA as 127.64 mg EDTAE/g d.w., 23.55 mg GAE/g d.w., 19.94 RE/g d.w., 26.77 mg AAE/g d.w. and 5.37 mg AAE/g d.w., respectively. For UAE, the optimal parameters were 30 mL/g SSR, 39 % DES concentration, 54.8 degrees C temperature and 17.48 min time with predicted ICA, TPC, TFC, FRAP, and RSA as 127.80 mg EDTAE/g d.w., 18.58 mg GAE/g d.w., 23.36 RE/g d.w., 23.33 mg AAE/g d.w., and 5.79 mg AAE/g d.w., respectively. The models were efficient and supported by statistical and validation studies. MAE, however, used far less time than UAE. The outcomes of the study have important implications for iron overload syndrome and oxidative stress. The developed methods can, thus, be proposed as strong candidates for industrial applications obtaining bioactive compounds from abundantly available leaves of A. indica.