Optical rotations were recorded using a Rudolph Research Analytical automatic polarimeter (Rudolph Research Analytical, Hackettstown, NJ, USA). Circular dichroism (CD) was measured on a JASCO J-815 CD spectro polarimeters (JASCO Corporation, Tokyo, Japan). IR spectra were acquired by KBr disk method on a Shimadzu FTIR-8400S spectrometer (Shimadzu Co. Ltd., Tokyo, Japan). 1D and 2D nuclear magnetic resonance (NMR) spectra were recorded on a Bruker AV-500 spectrometer (Bruker Biospin Group, Karlsruhe, Germany) with TMS as an internal standard. Mass spectra were measured on Thermo Scientific Q Exactive Focus Orbitrap mass spectrometer (Waltham, MA, USA) for HRESIMS. GC-MS analysis was conducted by GCMS-TQ8050 (Shimadzu Co. Ltd., Tokyo, Japan) using the Rtx-5MS column (30 m × 0.25 mm × 0.25 μm).
Semi-preparative HPLC was conducted on an Agilent C18 column (250 × 10 mm I.D., 5 μm) equipped with a LC-6AD pump and a Shimadzu SPD-20A UV-Vis detector (Shimadzu Co. Ltd., Japan). Column chromatography (CC) was performed with silica gel (100–200 and 200–300 mesh, Qingdao Marine Chemical plant, Qing dao, China), ODS-C18 (50 μm, YMC Co. Ltd., Kyoto, Japan), and Sephadex LH-20 (18–110 μm, GE healthcare, Fairfield, CT, USA). Chromatographic or analytical grade solvents were used for isolation and separation procedures.
Semi-preparative HPLC was conducted on an Agilent C18 column (250 × 10 mm I.D., 5 μm) equipped with a LC-6AD pump and a Shimadzu SPD-20A UV-Vis detector (Shimadzu Co. Ltd., Japan). Column chromatography (CC) was performed with silica gel (100–200 and 200–300 mesh, Qingdao Marine Chemical plant, Qing dao, China), ODS-C18 (50 μm, YMC Co. Ltd., Kyoto, Japan), and Sephadex LH-20 (18–110 μm, GE healthcare, Fairfield, CT, USA). Chromatographic or analytical grade solvents were used for isolation and separation procedures.