Natural Deep Eutectic Solvents for Enhanced Polyphenol Extraction From Edible Medicinal Plants With an Emphasis on <i>Citrus limon</i> L.

ABSTRACT Holy basil, lemon, and betel are known for various ethnomedicinal properties due to multiple phytochemicals, especially phenolics. Natural deep eutectic solvents act as a greener alternative for extracting bioactives from plant materials. The objective of this study was to optimize the extraction of phenolics using NADES‐based systems. A total of 16 different molar combinations of sugar, organic acid, and choline chloride were used. For holy basil and lemon, the highest total phenolic content (TPC) was 13.50 ± 0.01 and 11.08 ± 0.10 µg gallic acid equivalent per mg dry biomass (GED) when extracted with malic acid:citric acid system (1:1), and while in betel, highest TPC was observed in 14.60 ± 0.01 GED in tartaric acid:choline chloride (1:2) based system. Liquid chromatography‐mass spectroscopy analysis revealed the presence of 19 flavonoids and phenolics in lemon leaf extracts. These extracts also showed antioxidant and antimicrobial activities (against Escherichia coli and Streptococcus ). Scanning electron microscopy studies of E. coli cells treated with NADES‐based lemon leaves revealed disruption of cellular membranes leading to the formation of multiple craters, thereby causing intracellular content leakage causing lysis. In conclusion, NADES systems can lead to higher extraction efficiency and bioactivity of target molecules, acting as a sustainable alternative to conventional organic solvents.