Zorbax 300sb c18 rp column

All the starting materials were purchased from Aladdin or Sangon Biotech. Commercial reagents were directly used, unless otherwise noted. All chemicals are in reagent grade or better. NTR was purchased from Sigma-Aldrich [1 U is defined as the enzyme activity that cleaves 1 μmol of the standard substrate per minute in the presence of menadione and NADH at 37°C]. A 300-MHz Bruker AV 300 spectrometer was used to obtain the ¹H nuclear magnetic resonance (NMR) and ¹³C NMR spectra. Electrospray ionization–MS spectra were obtained on an LCQ Advantage MAX ion trap mass spectrometer (Thermo Fisher Scientific). MALDI ionization–time-of-flight (TOF)/TOF mass spectra were obtained on a TOF Ultraflex II mass spectrometer (Bruker Daltonics). An Agilent 1200 HPLC system, which was equipped with a G1322A pump, an in-line diode array ultraviolet detector, and an Agilent Zorbax 300SB-C18 RP column, was used for HPLC analyses. TEM observations were conducted on a JEM-2100F electron microscope with a working acceleration voltage of 100 kV. Normal HeLa cells were cultured in Dulbecco’s modified Eagle’s medium (DMEM; HyClone) containing 10% fetal bovine serum at 37°C, 5% CO₂, and humid atmosphere. Hypoxic HeLa cells were cultured in DMEM (HyClone) with 10% fetal bovine serum at 37°C, 1% O₂, and 5% CO₂.