1260 infinity pump

Optical rotations were measured on a JASCO P-2000 polarimeter using a 1-cm cell. UV and electronic circular dichroism (ECD) spectra were recorded on a Chirascan CD spectrometer (Applied Photophysics, Surrey, UK). 1D and 2D NMR spectra were obtained with Bruker AVANCE III HD 850 spectrometers (Bruker, Billerica, MA, USA) at the National Center for Interuniversity Research Facilities at Seoul National University (NCIRF). UHPLC-Q/TOF-MS analyses were performed on a Waters Acquity UPLC system (Waters Co., Milford, MA, USA) coupled with a Waters Xevo G2 QTOF mass spectrometer (Waters MS Technologies, Manchester, UK) that was equipped with an electrospray interface (ESI). The absolute configurations of the amino acids in compounds 1 and 2 were determined using an Agilent 6120 quadruple MSD consisting of a 1260 Infinity pump, a 1260 Infinity autosampler, a 1260 Infinity DAD (Agilent Technologies, Santa Clara, CA, USA), and an Agilent Zorbax SB-C₃ column (150 × 4.6 mm, 5 μm) at 50 °C. Semi-preparative HPLC separations were performed with a system consisting of a Gilson 321 Pump and a UV/Vis-151 detector (Gilson Inc., Middleton, WI, USA). Extra-pure grade solvents for extraction, fractionation, and isolation were purchased from Dae Jung Pure Chemical Engineering Co. Ltd., Siheung, Korea. Deuterated DMSO for NMR analyses was purchased from Merck (Darmstadt, Germany).

HPLC analyses were primarily performed using an Agilent Technologies 1260 infinity pump and a 1260 infinity II ultraviolet (UV) detector (Palo Alto, CA, USA). The chromatography system consisted of a 1260 infinity quaternion liquid. A microplate spectrophotometer (Epoch 2, Biotek Instruments, Winooski, VT, USA) was used in the assay of the scavenging activity on the DPPH radical.
The separation was performed on a Diamonsil Plus C18 column (4.6 × 250 mm, 5 µm). The mobile phase was composed of 0.1% aqueous formic acid (A, pH 2.8) and acetonitrile (B), using a gradient elution of 10% B at 0–2 min, 10–30% B at 2–30 min, 30–70% B at 30–45 min, and 70–10% B at 55–60 min. The flow rate was set at 1.0 mL·min⁻¹, with the temperature maintained at 30 °C. The injection volume was 10 µL and the detection wavelength was set at 350 nm.