Silica gel sio2

Optical rotations were measured with a JASCO P-1020 polarimeter (JASCO, Tokyo, Japan). UV spectra were taken on a Beckman DU640 spectrophotometer (Beckman Coulter Inc., Brea, CA, USA). IR spectra were recorded on a NICOLET NEXUS 470 spectrophotometer (International Equipment Trading Ltd., Vernon Hills, IL, USA) in KBr discs, with υ in cm⁻¹. ¹H-, ¹³C-NMR, DEPT, and 2D NMR spectra were recorded on a JEOL JNM-ECP 600 (JEOL Ltd., Tokoyo, Japan) and Varian 500 spectrophotometers (Varian, Palo Alto, CA, USA), with δ in ppm with solvent residual signals as internal standards (DMSO: δ_H 2.50 ppm, δ_C 39.5 ppm), and J in Hz. Semi-preparative HPLC was performed using an ODS column (YMC-Pack ODS-A, 10 × 250 mm, 5 µm) (YMC Co. Ltd., Kyoto, Japan).; The ratios of solvent were described as a mixture by v/v. HR-ESI-MS was measured on a Thermo Scientific LTQ Orbitrap XL mass spectrometer (Thermo Fisher Scientific Inc., Waltham, MA, USA) in m/z. A Sephadex LH-20 (GE Healthcare, Uppsala, Sweden) and silica gel (SiO₂; 100–200 mesh, 200–300 mesh, and 300–400 mesh; Qingdao Marine Chemical Inc., Qingdao, China) were used for column chromatography (CC), and TLC was carried out on silica gel GF₂₅₄ (10–40 mm; Qingdao Marine Chemical Inc., Qingdao, China) plates; spots were visualized under UV light and by spraying with 5% H₂SO₄ in C₂H₅OH (v/v) followed by heating.

All solvents used were of analytical grade and obtained from commercial sources. Solvents were filtered through a microporous membrane of 0.45 μm before used for HPLC analyses. TLC: precoated silica gel GF₂₅₄ plates (Qingdao Marine Chemical Co., Ltd., Qingdao, China); visualized by UV light and spraying with 10% H₂SO₄ in 95% EtOH followed by heating. Column chromatography (CC): silica gel (SiO₂; 200–300 mesh; Qingdao Marine Chemical Co., Ltd.), MCI CHP20P gel (75–150 μm; Mitsubishi Chemical Industries Ltd., Tokyo, Japan) and ODS C-18 gel (50 μm; YMC Co., Ltd., Kyoto, Japan). Optical rotations: Rudolph Research Autopol III automatic polarimeter. UV Spectra: Shimadzu-UV-2450 spectrometer; λ_max (log ε) in nm. IR Spectra: Thermo-Nicolet-6700 FT-IR microscope instrument (FT-IR microscope transmission). NMR spectra: Bruker AM-500 apparatus with chemical shifts given in ppm (δ) using TMS as an internal standard, J in Hz. ESI- and HR-ESI-MS: Agilent-6210-LC/TOF mass spectrometer; in m/z.