Lichroprep rp c18 gel

Optical rotations were measured on a Rudolph Autopol IV automatic polarimeter (NJ, USA). ECD spectra were recorded on a JASCO J-810 CD spectrophotometer (JASCO, Japan). UV spectra were scanned using a Shimadzu UV-2450 spectrophotometer (Tokyo, Japan). IR spectra were obtained using a Thermo Nicolet Nexus 470 FT-IR spectrophotometer (MA, USA) with KBr pellets. The 1 H, 13 C, and 2D NMR spectra were obtained on a Bruker 400 MHz spectrometer (Bruker-Biospin, NEO, USA). The HRESIMS data were acquired from an LCMS-IT-TOF system equipped with a Prominence UFLC system and an ESI interface (Shimadzu, Kyoto, Japan). Silica gel (200-300 mesh, Qingdao Marine Chemical Inc., Qingdao, People's Republic of China), LiChroprep RP-C 18 gel (40-63 μm, Merck, Germany), and Sephadex LH-20 (Pharmacia, LA, USA) were employed for open column chromatography (CC). HPLC was carried out on a Shimadzu LC-20AT pump system (Shimadzu Corporation, Tokyo, Japan) equipped with an SPD-M20A photodiode array detector monitoring at 230 and 280 nm. A semi-preparative HPLC CAPCELL PAK C 18 column (250 × 10 mm, 5 μm), a CHIRALPAK IC column (4.6 × 150mm, 5 μm) and a CHIRALCEL OJ-H column (4.6 × 150mm, 5 μm) were employed for the isolation. TLCs were performed using pre-coated GF 254 plates. All purified compounds submitted for bioassay were at least 95% pure as judged by HPLC and supported by 1 H NMR analysis.