Optimization of ultrasound-assisted extraction of bioactive alkaloids from Stephania cambodica using response surface methodology

An ultrasound-assisted extraction (UAE) was optimized for the extraction of three bioactive alkaloids, namely, palmatine, roemerine, and tetrahydropalmatine from the tuber of Stephania cambodica. The performance of UAE and microwave-assisted extraction (MAE) was compared with that of percolation. UAE and MAE are also more environmentally friendly and use less toxic chemicals. MAE was as efficient as UAE for the extraction of tetrahydropalmatine; however, UAE significantly enhanced extraction yields of palmatine and roemerine. The influence of effective variables viz. liquid–solid ratio, percentage of ethanol, and time on UAE was then investigated using response surface methodology. The optimal UAE conditions were found to be ethanol 52%, time 9 min, and liquid–solid ratio 26.6:1 mL/g. Structural change was conducted by scanning electron microscopy. These findings suggest that UAE is a practical extractive procedure for preparation of alkaloid-rich extract for pharmacological investigation and for analytical control of S. cambodica tuber.