Ods a c18 column

The chemical profiles of the flavonoid extracts from S. tonkinensis before and after purification were analyzed using a LC-20AD (Shimadzu, Tokyo, Japan) system equipped with a photodiode array detector (SPD-M20A). A YMC-Pack ODS-A C18 column (4.6 mm × 250 mm, 5 μm) was used for separation at 30 °C. The mobile phase consisted of methanol (A) and 0.05% TFA in water (B) with a gradient elution as follows: 0–40 min, 30–75% B; 40–60 min, 75–80% B. The total flow rate was 0.5 mL/min, and the detection wavelength was set at 284 nm.

The NMR spectroscopy spectra were obtained on the Bruker ASCEND 600 MHz NMR spectrometer equipped with CryoProbe (Bruker Biospin GmbH, Rheinstetten, Germany). Optical rotations were recorded on an Anton Paar MCP-100 polarimeter (Anton Paar GmbH, Austria), with MeOH as solvent. UV spectra were recorded on a UV-1800 spectrometer (Shimadzu Co., Kyoto, Japan). IR spectra were measured on the Nicolet 6700 spectrometer (Thermo, Madison, WI, USA). CD spectra were measured on a J-815 spectropolarimeter (Jasco Co., Japan). Crystallographic data was collected on an XtaLAB Pro: Kappa single four-circle diffractometer using Cu Kα radiation (Rigaku Co., Tokyo, Japan). HRESIMS spectra data were recorded on a MaXis quadrupole-time-of-flight mass spectrometer (Bruker Biospin GmbH, Rheinstetten, Germany). Normal and reverse phase column chromatography (C. C.) was performed using silica gel (200–300 mesh, Qingdao Haiyang Chemical, Qingdao, China) and ODS (YMC Co., Ltd., Kyoto, Japan), respectively. Normal and reverse phase thin-layer chromatography (TLC) was conducted using silica gel 60 F₂₅₄ and RP-18 F₂₅₄ (Merck Millipore Co., Darmstadt, Germany). HPLC was performed using Shimadzu LC-16P system (Shimadzu Co., Kyoto, Japan) with YMC-ODS-A C₁₈ Column (20 × 250 mm, 5 µm) for separation. Analytical and HPLC grade reagents (Macklin Co., Shanghai, China) were used for isolation procedures.

LC-MS was performed on an Agilent 1260 Infinity LC coupled to a 6230 TOF (HRESI) equipped with an YMC-ODS-A C18 column (250 × 4.6 mm, 5 µm) (YMC Co., Ltd., Kyoto, Japan) with a constant temperature of 35 °C. Analytic and semi-preparative HPLC was performed on a SHIMAZU LC-20 equipped with a DAD detector using a YMC-ODS-A C18 column (250 × 4.6 mm, 5 µm) and a YMC-ODS-A C18 column (250 × 10.0 mm, 7 µm), respectively. NMR spectra were recorded in CDCl₃ and CD₃OD on a JEOL JNM-ECZ600R/S1 spectrometer (600 MHz) (JEOL, Tokyo, Japan). HRESIMS spectra were measured on an Agilent 6230 TOF mass spectrometer (Agilent Technologies, Palo Alto, CA, USA).