Pre coated silica gel gf254 plates

LiChroprep Rp-18 (40–63 μm, Merck, Darmstadt, Germany), silica gel (200–300 mesh, Qingdao Haiyang Chemical Co. Ltd., Qingdao, China) and Sephadex LH-20 (25–100 μm, GE Healthcare Bio-Science AB, Uppsala, Sweden) were used as a stationary phase for column chromatography (CC). Precoated silica gel GF254 plates, 0.2–0.25 mm thick (Qingdao Haiyang Chemical Co., Qingdao, China), were used for thin layer chromatography (TLC) analysis, spots were visualized under a UV radiation by spraying with a sulfuric acid: ethanol (1:9, v/v) solution followed by heating. 4-Nitrophenyl-α-D-glucopyranoside (pNPG), α-glucosidase, quercetin and acarbose were purchased from sigma chemical (Merck KGaA, Darmstadt, Germany).

Optical rotations were determined on a Perkin-Elmer 341 polarimeter. UV spectra were recorded on a Shimadzu UV-2550 spectrophotometer. IR spectra were acquired on a Perkin-Elmer 577 spectrometer. NMR spectra were measured on a Bruker AM-400 spectrometer with TMS as internal standard. ESIMS and HRESIMS were performed on a Bruker Daltonics Esquire 3000 plus and a Waters-Micromass Q-TQF Ultima Global mass spectrometer, respectively. Semi-preparative HPLC was performed on a Waters 1525 binary pump system with a Waters 2489 detector (210 nm) and equipped with a YMC-Pack ODS-A (250 × 10 mm, S-5 μm). Silica gel (200–300 mesh, Qingdao Haiyang Chemical Co., Ltd.), C₁₈ reversed-phase (RP-18) Silica gel (20–45 μm, Fuji Silysia Chemical Ltd.), CHP20P MCI gel (75–150 μm, Mitsubishi Chemical Corporation), and Sephadex LH-20 gel (Amersham Biosciences) were used for column chromatography (CC). Pre-coated Silica gel GF₂₅₄ plates (Qingdao Haiyang Chemical Co., Ltd.) were used for TLC detection. All solvents used for CC were of analytical grade (Shanghai Chemical Reagents Co., Ltd.), and solvents used for HPLC were of HPLC grade (J & K Scientific Ltd.).

Optical rotations were acquired in MeOH using a p-1010 polarimeter (Jasco, Easton, MD, USA). Infrared spectra were measured on an Avatar 370 FT-IR spectrometer (Nicolet, Carlsbad, CA, USA) with KBr disks. HRESIMS were acquired on a LCQ^DECA XP instrument (Finnigan, San Jose, CA, USA) and a Q-TOF 1290 LC/6224 MS system (Agilent, Santa Clara, CA, USA). NMR spectra were recorded on an AVANCE III 500 MHz spectrometer (Bruker, Zürich, Switzerland) with tetramethylsilane(TMS) as the internal standard. Silica gel (200–300 mesh, Qingdao Haiyang Chemical Co., Ltd., Qingdao, China), MCI gel (75–150 μm, Mitsubishi Chemical Industries Ltd., Tokyo, Japan), D-101 macroporous resin (Chemical Plant of Nankai University, Tianjin, People’s Republic of China), C₁₈ reverse-phased silica gel (40–75 μm, Fuji, Kasugai, Japan), and Sephadex LH-20 gel (Amersham Pharmacia Biotech., Piscataway, NJ, USA) were performed on column chromatography. Precoated silica gel GF254 plates (Qingdao Haiyang Chemical Co., Ltd., Qingdao, China) were used for TLC. D-Quinovose and L-arabinose were purchased from Nantong Feiyu Biological Technology Co., Ltd. (Nantong, Jiangsu, China). All solvents were of analytical grade (Tianjin Yongda Chemical Reagent Co., Ltd., Tianjin, China).