Abstract: In this study,an aqueous two-phase system (ATPS) based on ethanol/(NH₄)₂SO₄ was evaluated for the extraction of lignans from Phyllanthus niruri. BoxBehnken design (BBD) was used to study the effects of salt concentration,ethanol concentration and ultrasonic extraction time on the partition behavior of main bioactive components lignans hypophyllanthin.The results showed 26.54% (w/w) (NH₄)₂SO₄, 21% (w/w) ethanol,20 min of ultrasonic extraction for hypophyllanthin were the optimal conditions with partition coefficient of 76.62.Furthermore,the cyclohexane was used for another step extraction on upper phase,under which 3.18 mg/g hypophyllanthin were obtained.The ATPS was firstly used to separate and purify hypophyllanthin from P.niruri and higher yields were obtained comparing with traditional column chromatography.The developed ATPS method was easier,greener and cheaper.It provided a new approach for the separation of hypophyllanthin.

Key words: aqueous two-phase extraction, Box-Behnken design, lignans, hypophyllanthin