Neutral alumina

α-Crocin (≥98%) and geniposide (≥98%) of analytical grade were purchased from Aladdin (Shanghai, China). HPLC grade acetonitrile was obtained from J&K Chemical Ltd. (Shanghai, China). Silica gel (100~200 mesh), Diatomite (filter aid, flux calcined, D50: 19.6 μm), neutral alumina (100 to 200 mesh), basic zinc carbonate (AR, 100 to 200 mesh), calcium carbonate (AR, 99%, 100 to 200 mesh) and activated carbon (AR, 200 mesh, brown) were obtained from Sinopharm Chemical Reagent Co. (Shanghai, China). Aluminum polychloride (PAC) (aluminum content ≥29%, basicity = 60% to 95%, pH = 3.5~5.0) was purchased from Tianjin Dingshengxin Chemical Reagent Co. (Tianjin, China). Deionized water was further purified using a Milli-Q water-purification system from Millipore (Bedford, MA, USA).

Optical rotations were recorded on a Rudolph Research Analytical Autopol III polarimeter. UV spectra were obtained using a Shmadzu UV-2700 UV–visible spectrophotometer, and IR spectra were obtained using a Nicolet iN10 MX spectrometer. NMR experiments were conducted on a Bruker AV-600 spectrometer in CDCl₃ with TMS as the internal standard at 25 °C. In the HMBC experiment, the ¹J_C-H was set to 120–170 Hz, and long-range J_C-H was set to 8 Hz. In the ROESY experiment, the mixing time was set to 200 ms. HRESIMS spectra were recorded on a Waters Xevo Q-Tof MS spectrometer. Preparative HPLC was conducted on a Waters LC Prep 150 System using various column, such as Waters XBridge Prep OBD C₁₈ column (30 × 150 mm, 10 μm), Waters XSelected CSH Prep C₁₈ column (19 × 250 mm, 5 μm), and YMC-Pack Ph column (10 × 250 mm, 5 μm). Neutral alumina (100–200 mesh, Sinopharm Chemical Reagent Co., Ltd., Shanghai, China) and ODS (50 μm, YMC, Kyoto, Japan) were used for column chromatography.