Agilent dd2 500 spectrometer

The lyophilized polysaccharides (20–30 mg) were co-evaporated with D₂O (99.96%) three times to remove the exchangeable protons and then finally dissolved in 500 μL D₂O. Deuterated acetone was used as an internal standard (2.08 ppm for ¹H-NMR and 29.34 ppm for ¹³C-NMR). ¹H-NMR, ¹³C-NMR, ¹H-¹H COSY, HSQC, HMBC, TOCSY and NOESY experiments were recorded at 298 K on an Agilent DD2-500 spectrometer (Agilent Technologies, Wilmington, DE, USA) [24 (link)].

The
reagents and solvents used in chemical synthesis were obtained from
commercial agents without further purification. All reactions were
monitored by using thin-layer chromatography (TLC). All final compounds
were purified by a column chromatography on silica gel (300–400
mesh). The NMR spectra were recorded on Agilent DD2 500 spectrometer
(Agilent Technologies Inc., USA) or Bruker AVANCE 600 spectrometer
(Bruker Company, Germany) in CDCl₃ or DMSO-d₆. The spectra of high-resolution mass (HRMS) were monitored
by Bruker MaXis 4G TOF mass spectrometer. The purities of all final
compounds were identified by HPLC analysis with the Agilent 1200 system
and were proved to be >95%. HPLC condition: Triart C18 reversed-phase
column, 5 μm, 4.6 mm × 250 mm, and flow rate 1.0 mL/min,
starting with a 15 min-gradient from 0.1% TFA in water and acetonitrile
1:9 mixture to 0.1% TFA in acetonitrile, then ending with 0.1% TFA
in acetonitrile for 5 min.