Microwave-assisted extraction of bioactive compounds from Urtica dioica using solvent-based process optimization and characterization

The extraction of bioactive compounds using green technology is a crucial topic for both research and industrys. This present investigation examines the effect of different solvents, i.e., water, ethanol (80%), and NADES (ChCl: lactic acid), during microwave-assisted extraction of bioactive compounds from nettle leaves. The RSM-BBD approach was employed with power (300, 450, and 600 W), time (10, 15, and 20 min), and sample-to-solvent ratio (1:10,1:15, and 1:20) in relation to the water, ethanol, and NADES extract's TPC (mg GAE/g), TFC (mg GAE/g), and DPPH (%IA). The optimum extraction conditions obtained were 300 W, 10 min, and 1:10 sample-to-solvent ratio for water, 300 W, 17 min, and 1:10 sample-to-solvent ratio for ethanol (80%), and 300 W, 10 min, and 1:13 sample-to-solvent ratio for NADES. Additionally, TPC (mg GAE/g), TFC (mg GAE/g), DPPH (%IA), ABTS (%), and FRAP (µM AA equivalent) of optimized extracts were compared. The antimicrobial potential of water, ethanol, and NADES extracts was also investigated against pathogenic bacteria, i.e., Staphylococcus aureus, Streptococcus pyogenes, and E. coli. Furthermore, the optimized extracts were analysed using U-HPLC, GC-MS, and LC-MS. The results highlight the suitability of microwave-assisted extraction of nettle leaf extract using NADES (ChCl: lactic acid) to obtain an extract with high antioxidant activity and good antimicrobial potential.