L 2000 hplc system

Optical rotations were measured on a JASCO P-1020 digital polarimeter. UV spectra were recorded on a HITACHI UH 5300 UV spectrophotometer. ECD data were acquired on a J-815-150S Circular Dichroism spectrometer. IR spectra were recorded on a Nicolet-Nexus-470 spectrometer using KBr pellets. NMR spectra were acquired by a JEOL JEM-ECP NMR spectrometer (500 MHz for ¹H and 125 MHz for ¹³C), using TMS as an internal standard. HRESIMS were measured on Agilent 1290 Infinity II UHPLC/6530 Q-TOF MS for compounds 1 and 2, and Thermo MAT95XP high resolution mass spectrometer for compound 3. Samples were analyzed and prepared on a Hitachi L-2000 HPLC system coupled with a Hitachi L-2455 photodiode array detector and using a semi-prepared C₁₈ column (Kromasil 250 × 10 mm, 5 μm). Silica gel (Qing Dao Hai Yang Chemical Group Co.; 300–400 mesh) and Sephadex LH-20 (Amersham Biosciences) were used for column chromatography (CC). Precoated silica gel plates (Yan Tai Zi Fu Chemical Group Co.; G60, F-254) were used for thin-layer chromatography.

The Optical rotations were measured on a JASCO P-1020 digital polarimeter (Jasco Corp., Tokyo, Japan). UV spectra were recorded by a Milton Roy UV–VIS spectrophotometer (Hitachi, Tokyo, Japan). IR spectra were performed on a Nicolet-Nexus-470 spectrometer using KBr pellets (Thermo Electron, Waltham, MA, USA). NMR spectra were tested by a JEOL JEMECP NMR spectrometer (600 MHz for ¹H NMR, 150 MHz for ¹³C NMR and 500 MHz for NOE spectra, JEOL, Tokyo, Japan) using tetramethylsilane (TMS) as an internal standard. ESIMS spectra were measured on a Micromass Q-TOF spectrometer (Waters Corp., Manchester, UK). ECD spectra were obtained on a JASCO J-815 circular dichroism spectrometer (JASCO Electric Co., Ltd., Tokyo, Japan). In the biological assay, the optical densities (OD) were acquired by a multimode reader Spark 10M (Tecan, Männedorf, Switzerland). Semipreparative HPLC was performed on a Hitachi L-2000 HPLC system coupled with a Hitachi L-2455 photodiode array detector and a Kromasil C₁₈ semipreparative HPLC column (250 mm × 10 mm, 5 μm). Silica gel (Qingdao Haiyang Chemical Group Co., Qingdao, China) and Sephadex LH-20 (Amersham Biosciences Inc., Piscataway, NJ, USA) were used for column chromatography (CC). Precoated silica gel GF254 plates (Yantai Zifu Chemical Group Co., Yantai, China) were used for thin layer chromatography (TLC).