Dip 360

The purified compound 1 was subjected to spectroscopic analyses (UV, IR, ¹H-NMR, ¹³C-NMR, ESI, and MS/MS studies) for identification and characterization. The optical measurements were conducted by using a polarimeter (JASCO DIP360, Jasco Co., Tokyo, Japan). A Bruker ATR-Tensor 37 spectrophotometer (Bruker, Ettlingen, Germany) was used to record the IR spectra. To obtain the ESI mass spectra, a QSTAR mass spectrometer (Applied Biosystems, Foster, CA, USA) with capillary voltage of 5–5.5 kV was used. The NMR spectra (¹H and ¹³C) were obtained by using a Bruker NMR spectrometer (Burker, Fallanden, Switzerland) operated at 600 MHz and 150 MHz, respectively.

To assess the UV spectrum of compounds, (Shimadzu UV-240, Hitachi U-3200, Kyoto, Japan) UV-240 spectrophotometers were used. On IRA-I and JASCO-320-A spectrophotometers, respectively, IR spectra have been reported. On Bruker AM-400, AM-500, and AM-600 spectrometers (Thermo Fisher Scientific, Waltham, MA, USA) with 400, 500, and 600 aspect data systems, the ¹H-NMR and ¹³C-NMR spectra were observed at 400, 500, and 600 MHz z (instrument used Bruker Biospin, Karlsruhe, Germany). As an internal guide, TMS (tetramethylsilane) was used. The JMS-HX-110 data system spectrometer was used to measure the EI-MS spectra of compounds. The Jasco-DIP-360 digital polarimeter (JASCO, Tokyo, Japan) was used to determine the optical rotation of the compounds. TLC was performed with G-25-UV254 pre-coated silica gel plates, and detection was carried out at 254 nm and 10% H₂SO₄ by ceric sulphate. For column chromatography and flash chromatography, respectively, silica gel (E. Merck,70–230 mesh) and silica gel (E. Merck, 230–400 mesh) were used.

Optical rotations were measured using a JASCO DIP-360 (Tokyo, Japan automatic digital polarimeter). IR and UV spectra were recorded using the JASCOFT-IR 620 spectrophotometer and UV-2600 instrument, respectively. 1D and 2D NMR spectra were recorded on Bruker DRX-400 spectrometer (400 MHz for ¹H-NMR, Karlsruhe, Germany) with TMS used as internal standard. The mass spectra were obtained on Agilent Series1100 SL mass spectrometer (Agilent Technologies Inc., Santa Clara, CA, USA), and Bruker Daltonics mass spectrometer (Bruker Daltonics Inc. Billerica, MA, USA) with an electrospray ionization source. Circular Dichroism (CD) was obtained using the Chirascan, Applied Photophysics Ltd. (Surrey, UK). HPLC was performed using a system comprised of a CCPM pump (Tosoh, Tokyo, Japan), a CCP PX-8010 controller (Tosoh), an RI-8010 detector (Tosoh) or a Shodex OR-2 detector (Showa-Denko, Tokyo, Japan), and a Rheodyne injection port. A Capcell Pak C18 UG120 column (10 mm i.d. × 250 mm, 5 μm, Shiseido, Tokyo, Japan) was employed for preparative HPLC. Sephadex LH-20 (GE Healthcare Bio-Sciences AB, Uppsala, SE, USA) was used for column chromatography (CC), and a silica gel GF₂₅₄ (10–40 mm, Haiyang Co., Qingdao, China) was used for preparative TLC as precoated plates. TLC spots were visualized under UV light through dipping into 5% H₂SO₄ in alcohol. All chemicals used were analytical grade.