Variant unity inova 500 spectrometer

UV spectra was measured using a TECAN Infinite M200 pro, with MeOH. The IR spectra and mass spectra were recorded on a SHIMADZU IR Prestige-21 in KBr and Waters Xevo QTOF MS, respectively. Using an NMR JEOL ECZ-500 and Variant Unity INOVA-500 Spectrometer (Agilent Technologies, Santa Carla, CA, USA), the NMR data was recorded at 500 MHz for ¹H and 125 MHz for ¹³C, using TMS as internal standard. Column chromatography was conducted on the silica gel 60 (70–230 and 230–400 mesh, Merck, Kenilworth, NJ, USA), after which TLC analysis was carried out on 60 GF₂₅₄ (Merck, 0.25 mm) using various solvent systems, in order to detect spots by irradiating under ultraviolet-visible light (257 and 364 nm) and heating of silica gel plates, sprayed with H₂SO₄ in EtOH (10%).

The spectra of ¹H NMR were acquired with a Variant Unity INOVA-500 Spectrometer (Agilent Technologies, Santa Clara, United States) operating at 500 MHz. The ¹H presaturation mode was applied to suppress the signal of H₂O. For each ¹H NMR spectrum, 128 scans were collected into 64 K data points using a spectral width of 8012.8 Hz with an acquisition time of 2.720 s and a delay time of 2.0 s. The Free Induction Decay (FID) files of the ¹H NMR spectra were further processed with an ACD/Labs 12.0 software (ACD/Labs, Toronto, Canada). The baseline correction of each spectrum was performed. TSP (3-(trimethylsilyl)-2,2,3,3-tetradeuteropropionic acid sodium salt) signal was used for calibrating the chemical shift.

TLC aluminium sheets 20 × 20 cm silica gel 60 F254, silica gel 60 (Merck, Darmstadt, Germany), and pre-coated TLC glass plates SIL G-25 UV254, 0.25 mm silica gel (Sigma, St. Louis, MO, USA) were used for thin layer chromatography analysis, vacuum liquid column chromatography, and preparative TLC, respectively. Spots on TLC were visualized by using spraying reagent of Liebermann Burchard for terpenoid/steroid detection. Shimadzu QP-2010 Gas Chromatograph Mass Spectrometer Ultra (Shimadzu, Kyoto, Japan) was used for GC-MS analysis. Acquity UPLC I-Class System with the XEVO G2-XS QTof Mass Spectrometer (Waters, Milford, MA, USA) was used for LC-MS/MS analysis, and NMR JEOL ECZ-500 and Variant Unity INOVA-500 Spectrometer (Agilent Technologies, Santa Carla, CA, USA) were used to elucidate the structural compounds. The nuclear magnetic resonance (NMR) was recorded at 500 MHz for ¹H and 150 MHz for ¹³C. Chemical shifts are given in δ (ppm) relative to TMS as internal standard, and deuterated chloroform was used as the solvent. The SARS-CoV-2 3CLpro #78042 assay kit was purchased from BPS Bioscience Inc., (San Diego, CA, USA).