2.2. Isolation and HPLC conditions for sophoricoside analysis from S. japonica
Sophoricoside was isolated from the mature seeds of S. japonicaby repeated column chromatography. To quantify sophoricoside, an Agilent 1260 Infinity II Quat Pump (CA, USA) was used. Quantitative analysis was performed using a reverse-phase system. Separation was conducted on an INNO C18 column (25 cm × 4.6 mm, 5 μm). Column temperature was maintained at 30°C, and the flow rate was set at 1 mL/min. The mobile phase was comprised of (A) water (0.5% acetic acid) and (B) acetonitrile, and the elution was conducted in a gradient system: 92% (A)-8% (B) for 2 min; reduced to 90% (A) for 25 min; reduced to 70% (A) for 23 min; reduced from 70% to 10% for 2 min; reduced from 10% to 0% for 8 min; and increased from 0% to 92% (A) for 5 min. The injection volume was 10 μL, and the UV absorbance was recorded at 270 nm.