Sustainable Extraction of the Tetrahydropalmatine Alkaloid from Stephania rotunda Lour. Tubers Using Eco-Friendly...

Tetrahydropalmatine (THP) is the major bioactive alkaloid in Stephania rotunda Lour. (Menispermaceae) with well-known pharmacological properties, such as antiaddiction, antitumor, and neuroprotective activities. In this study, a novel ultrasonic-assisted extraction method for the sustainable extraction of the tetrahydropalmatine alkaloid from S. rotunda Lour. tubers was developed and optimized. The study reports also the development and validation of an HPLC-PDA analytical method intended for the quantification of THP in S. rotunda medicinal plant accompanied by a rapid and straightforward sample preparation procedure. A set of environmentally friendly and human-safe solvents was systematically evaluated for their extraction yield of THP, and the response surface methodology (RSM) was used for the optimization of extraction. Among the solvents studied, lactic acid showed the highest extraction yield under the optimized conditions of extraction: 90% lactic acid concentration, solvent-to-material ratio of 40 mL/g, and ultrasonic-assisted extraction at 65 °C for 10 min. With the ultrasound-enhanced extraction, the yield of THP was 1.2-1.4 times higher than that obtained with conventional solvent extraction methods. Moreover, XAD-8 resin demonstrated superior recovery performance with a THP recovery rate of 92.02 ± 0.60%. This is the first study encompassing a "green" ultrasonic-assisted solvent extraction, a validated quantification method, and resin adsorption techniques for the sustainable and efficient extraction and recovery of THP from S. rotunda.