Extraction and identification of polyphenol from Camellia oleifera leaves using tailor-made deep eutectic solvents based on COSMO-RS design

Camellia oleifera leaf is a rich source of polyphenols. In this study, 50 polyphenolic compounds from C. oleifera leaves was identified by UHPLC-Q-TOF-MS/MS. Accordingly, COSMO-RS was used in the design of deep eutectic solvents (DESs) to extract those polyphenols. 17 types of choline chloride (ChCl)-based DESs molecules (ChCl-acid, ChCl-sugar, ChCl-alcohol, ChCl-amine and amide) were synthetized into virtual cluster molecules with Materials Studio software. They were used to determine the activity coefficients with the standard compounds. The results showed that the amine and amide-based DESs exhibited outstanding dissolution effects. Additionally, ChCl-acetamide was selected as the solvent in response surface methodology to optimize the ultrasound-assisted DES extraction process parameters, including ultrasonic power, ultrasonic time, and liquid–solid ratio, resulting in an improved total phenolic content of 131.63 ± 0.85 mg GAE/g. This study developed a system utilizing UHPLC-Q-TOF-MS/MS to acquire specific substances required for COSMO-RS calculations.