2.3 Solvent extraction of Qingjinju seeds
Qingjinju seeds were ground (model YC-04B, Shanghai Jinben Machinery Co., Ltd., Shanghai, China) for 30 s and mixed with hexane in a ratio 1:7 (w/v). The mixture was transferred to a closed glass reaction kettle and stirred for 2 h at 55 °C in a water bath (W-O, Shanghai Shengshun Biotechnology Co., Ltd., Shanghai, China). The solution was decanted and the extraction was repeated three times. The solutions were then evaporated under reduced pressure at 60 °C and stored at 3 °C in a refrigerator.