Simultaneous extraction and purification of alkaloids from Sophora flavescens Ait. by microwave-assisted aqueous two-phase extraction with ethanol/ammonia sulfate system
A rapid and effective method of integrating extraction and purification for alkaloids from Sophora flavescens
Ait. was developed by microwave-assisted aqueous two-phase extraction (MAATPE) based on the
high efficiency of microwave-assisted extraction (MAE) and the demixing effect of aqueous two-phase
extraction (ATPE). The aqueous two-phase system (ATPS), ethanol/ammonia sulfate was chosen from
seven combinations of ethanol/salt systems, and its extraction properties were investigated in detail.
Key factors, namely, the compositions of ATPS, solvent-to-materials ratio, and the extraction temperature
were selected for optimization of the experimental conditions using response surface methodology (RSM)
on the basis of the results of the single-factor experiment. The final optimized conditions were, the compositions
of ATPS: ethanol 28% (w/w) and (NH4)2SO4 18% (w/w), solvent-to-material ratio 60:1, temperature
90 C, extraction time 5 min, and microwave power 780 W. MAATPE was superior to MAE, the latter
using a single solvent, not only in extraction yield but also in impurity content. Moreover, compared with
the combination of MAE and ATPE in the two-step mode, MAATP demonstrated fewer impurities, a better
yield (63.78 ± 0.45 mg/g) and a higher recovery (92.09 ± 0.14%) in the extraction and purification of alkaloids.
A continuous multiphase-extraction model of MAATPE was proposed to explicate the extraction
mechanism. MAATPE revealed that the interaction between microwave and ATPS cannot only cause plant
cell rupture but also accelerate demixing, improving mass-transfer from solid–liquid extraction to liquid–
liquid purification. MAATPE simplified procedures also contributed to the lower loss occurrence, better
extraction efficiency, and reduced impurity to target constituents.The Science and Technology Project of Guangzhou (No. 2008Z1-E301) and Faculty Development fund Project of Guangdong Pharmaceutical University (No. 52104109
