Cosmosil 75c18 opn

Melting points were determined on a Yanaco Micro MP apparatus. Optical rotations were measured on a JASCO P-2100 polarimeter (Hachioji, Tokyo, Japan). Infrared spectra were recorded on JASCO FT/IR-460 Plus spectrometer. 1D and 2D NMR were carried out using Bruker Avance 500 spectrometer (Bruker, Mass., Billerica, MA) with tetramethylsilane as an internal standard. ESI-MS data including high-resolution mass spectrum were measured on Shimadzu LCMS-IT-TOF spectrometer (Kyoto, Japan) HREIMS was recorded on a JEOL MStation JMS-700 spectrometer (JEOL Ltd., Tokyo, Japan). Column chromatography was performed using silica gel (Kanto, 40–50 μm, Tokyo, Japan), Cosmosil 75C18-OPN (Nacalai Tesque Inc., Kyoto, Japan) and Sephadex LH-20 (Dowex® 50WX2-100, Sigma-Aldrich, Tokyo, Japan). Analytical TLC was performed on pre-coated silica gel 60F₂₅₄ and RP-18 F₂₅₄ plates (0.25 or 0.50 mm thickness, Merck KGaA, Darmstadt, Germany). Cosmosil 5C18-AR-II (Nacalai Tesque Inc., Kyoto, Japan) was used for analytical and semi-preparative HPLC (250 × 4.6 mm for analytical HPLC, and 250 × 10.0 mm for semi-preparative HPLC).

Optical rotation values were determined using a JASCO P-1020 polarimeter. UV spectra were recorded using a Hitachi U-2900 spectrometer. ECD spectra were acquired with a JASCO J-820 spectropolarimeter and IR spectra were recorded using a Shimadzu FTIR-8400S spectrophotometer. NMR spectra were acquired with a JEOL JNM-ECZ 400S spectrometer with tetramethylsilane as an internal standard. ESI–MS data were obtained using an Agilent 6230 LC/TOF mass spectrometer. HPLC was performed on a Hitachi HPLC system equipped with an L-2130 pump, an L-2200 autosampler, an L-2300 column oven, and an L-2455 diode array detector. Silica gel AP-300 (Toyota Kako), Sephadex LH-20 (GE Healthcare), and Cosmosil 75C₁₈-OPN (Nacalai Tesque) were used for column chromatography (CC). Silica gel 60 F₂₅₄ and RP-18 F_254S (Merck) were used for TLC analysis.

G. rigescens was purchased from Huqingyutang Chinese Pharmacy Hangzhou, Zhejiang Province. The identity of this plant was confirmed by Associate Professor Liurong Chen (College of Pharmaceutical Sciences, Zhejiang University), and a voucher specimen (no. 20190620) was preserved in Zhejiang University, Institute of Materia Medica. Preparative high-performance liquid chromatography (HPLC) analysis was performed using a HPLC system equipped with Elite P-230 pumps (Dalian Elite Inc., China). An Agilent Technologies 6224A Accurate-Mass time-of-flight liquid chromatography–mass spectrometry (TOF LC/MS) system was used to measure the mass spectra (Agilent Technologies Inc., Beijing, China). A Bruker AV III-500 spectrometer was used to record the nuclear magnetic resonance (NMR) spectra (Bruker, Karlsruhe, Germany). NMR chemical shifts in δ (ppm) were referenced to solvent peaks of δ_C 49.0 for CD₃OD (Cambridge Isotope Laboratories, Inc., MA, USA). Octadecyl-silane (Cosmosil 75 C18-OPN, Nacalai Tesque, Japan) and RP-18 plates (0.25 mm) (Merck KGaA, Darmstadt, Germany) were used for column chromatography and thin-layer chromatography analysis, respectively [2 (link)]. Resveratrol (Res) was purchased from J&K Scientific Ltd. (Beijing, China) and was used as a positive control.