**3. Materials and Methods**

## *3.1. General Experimental Procedures*

HRESIMS data were obtained on a Waters Synapt G2 Q-TOF mass spectrometer (Waters Corporation, Milford, MA, USA). Optical rotations were measured on a Rudolph Research Analytical Autopol III polarimeter (Rudolph Research Analytical, Hackettstown, NJ, USA). 1D and 2D NMR spectra were acquired using a Bruker 600 MHz spectrometer (Bruker BioSpin GmbH, Rheinstetten, Germany). IR spectra were measured on a JASCO FT/IR-4100 spectrophotometer (JASCO Corporation, Tokyo, Japan). UV-visible spectra were measured by a Shimadzu UV-1650PC spectrophotometer. HPLC was carried out with a PrimeLine Binary pump (Analytical Scientific Instruments, Inc., El Sobrante, CA, USA) and a RI-101 detector (Shoko Scientific Co. Ltd., Yokohama, Japan). Semi-preparative HPLC was conducted using an ODS column (YMC-Pack-ODS-A, 250 × 10 mm i.d, 5 μM). Analytical HPLC was performed with an ODS column (YMC-Pack-ODS-A, 250 × 4.6 mm i.d, 5 μM). All the used reagents were purchased from Sigma-Aldrich (Merck KGaA, Darmstadt, Germany).
