Extraction mechanism and bio-activities of capsaicinoids from lantern peppers placenta using deep eutectic solvents

This study proposed ultrasound-assisted deep eutectic solvent (DES) for the extraction of capsaicinoids (CAP) from the placenta of lantern peppers. The DES of choline chloride-citric acid (ChCl-CA), with the highest CAP yield (8.25 mg/g) was screened. ¹H nuclear magnetic resonance and Fourier transform infrared spectroscopy showed that the ChCl-CA formed hydrogen bonds through -COOH of CA and N⁺Cl^- of ChCl. Furthermore, the CAP preferred the diffusion of ChCl during the extraction of CAP, which indicated that ChCl played a better solvent role in the DES via molecular dynamics. High-performance liquid chromatography results showed capsaicin (65.02 %) as the major compound in the extracts. Notably, DES-extracted CAP had excellent antioxidant activity and provided enhanced inhibition of Escherichia coli and Staphylococcus aureus. Thus, this study will provide a reference for the future use of DES in the extraction of other alkaloids, either in the laboratory or the industry.