Spectroscopic Characterization of Natural Compounds

The circular birefringence was measured on a P-2000 Digital Polarimeters. HR-ESI-MS spectrum was measured on an X500 QTOF mass spectrometer (Sciex, USA). IR spectra were measured on an Agilent 6530 Accurate-Mass spectrometer. The 1D and 2D NMR including ¹H-(500 MHz), and ¹³C-(125 MHz) NMR spectra were employed using AVANCE III HD 500 FT-NMR spectrometer (Bruker, Corp., Germany). CD spectrum was achieved using Applied Photophysics Chirascan spectropolarimeter. Column chromatography (CC) was performed using silica gel (60F245, and RP-18 F254s. Merck, Germany), Sephadex LH-20 (Sigma-Aldrich, USA), and Thin Layer Chromatography (TLC) was performed on silica gel 60 F254 [23 (link)]. The identified compounds were monitored under a UV lamp at 254 or 365 nm and heated immediately after spraying with 10 % H₂SO₄.