Agilent g3250aa

Optical rotations were measured on a Perkin-Elmer 341 automatic polarimeter (Perkin-Elmer). UV spectra were recorded in MeOH (1 mg/50 mL) on a UV 210A spectrophotometer (Shimadzu). NMR spectra were recorded on a Bruker DRX-500 and DRX-400 spectrometer (Bruker). The chemical shifts (δ) are reported in ppm using tetramethylsilane as an internal standard and the coupling constants (J) are given in Hertz (Hz). HRESI-MS spectra were recorded on Agilent G3250AA (Agilent) and AutoSpec Premier P776 spectrometers (Waters). Column chromatography (CC) was performed on self-packed open columns with silica gel from Qingdao Haiyang Chemical Co., Ltd (QHCC). Thin layer chromatography (TLC) analyses were conducted on glass sheets of silica gel GF₂₅₄ from QHCC and detected under a UV lamp at 254 or 365 nm and visualized by spraying 8 % phosphomolybdic acid-EtOH solution (w/v) or 5 % vanillin-H₂SO₄ (w/v) followed by heating, or visualized with iodine (I₂). Semi-preparative high performance liquid chromatography (HPLC) (Agilent 1200 Series) was performed on an YMC C₁₈ column (250 mm × 10 mm, 5 μm, YMC Karasuma-Gojo Bldg.). Fractions from all columns were collected by an auto-collecting apparatus and were combined according to TLC analyses. All other solvents and reagents were commercially purchased from Beijing Greenherbs Science and Technology Development Co., Ltd. and distilled prior to use.

Optical rotation was measured with a Jasco P-1020 digital polarimeter (JASCO, Tokyo, Japan). A Shimadzu UV–Vis 2550 spectrometer (Shimadzu, Kyoto, Japan) was used for collection of UV spectra. NMR spectra were acquired with a Bruker AM-400 spectrometer (Bruker, Karlsruhe, Germany) using TMS as the internal reference. A Nicolet Magna-IR 550 spectrometer (Thermo Nicolet, Madison, USA) was used for scanning IR spectroscopy with KBr pellets. Melting points were determined on a XRC-1 Melting Point Apparatus (Sichuan University Science Instrument, Chengdu, China) and were not corrected. ESI–MS analyses were recorded with an Agilent G3250AA (Agilent, Santa Clara, USA) and Auto Spec Premier P776 spectrometer (Waters, Milford, USA). Silica gel (200–300 mesh and 300–400 mesh; Qingdao Marine, Qingdao, China) and Sephadex LH-20 (GE Healthcare, Fairfield, USA) were used for column chromatography (CC). GF254 plates (Qingdao Marine, Qingdao, China) were used for thin layer chromatography, and spots were visualized by spraying with modified Dragendorff’s reagent or 10 % H₂SO₄ in ethanol followed by heating.

Silica gel (200–300 mesh), Lichroprep RP-18, and Sephadex LH-20 were applied to column chromatography. The TLC plate was purchased from Qingdao Marine Chemical Group Co. and used for chromatography analysis. One-dimensional and two-dimensional NMR data were acquired on a Bruker AVANCE-600 MHz NMR instrument (Bruker, Karlsruhe, Germany). Mass spectra were measured by spectrometers of Agilent G3250AA (Agilent, Santa Clara, CA, USA) and AutoSpec Premier P776 (Waters, Milford, MA, USA). Optical rotations and circular dichroism spectra were measured on a polarimeter (Jasco P-1020) and an Applied Photophysics Chirascan spectrometer (Applied Photophysics Ltd., Surrey, British). LC-MS analyses were performed on an instrument (LTQ ORBITRAP XL).