A New Phloroglucinol Glucoside from the Whole Plants of Glochidion eriocarpum

Experimental

General Procedures. Optical rotations were performed on a P-1020 polarimeter (JASCO, Tokyo, Japan). IR spectra were measured on a Bruker Tensor 27 spectrometer with KBr pellets. UV spectra were obtained on a 210A double-beam spectrophotometer (Shimadzu, Kyoto, Japan). 1D- and 2D-NMR spectra were run on Bruker DRX-500 and AV-600 instruments operating at 500 and 600 MHz for 1H, and 125 and 150 MHz for 13C, respectively. The MS data were recorded on a VG Auto Spec-3000 spectrometer (VG, Manchester, U.K.). HREIMS were recorded on a Waters Autospec Premier P776. Column chromatography (CC) was performed with Diaion HP20SS (Mitsubishi Chemical Industry, Ltd.), silica gel (200-300 mesh, Qingdao Haiyang Chemical Co., Ltd., Qingdao, People’s Republic of China), and Sephadex LH-20 (25-100 μm, Pharmacia Fine Chemical Co. Ltd. Japan).Thin-layer chromatography (TLC) was carried out on silica gel H-precoated plates (Qingdao Haiyang Chemical Co., Ltd., Qingdao, People’s Republic of China) with CHCl3/MeOH/H2O (8.5:1.5:0.1, 8:2:0.2 or 7:3:0.5, v/v) as develop-ing solvents. Spots were detected by spraying with 10% H2SO4 in EtOH followed by heating. Semi-preparative HPLC separation was performed on an Agilent 1260 liquid chromatography with a 5 μm Waters Sunfire-C18 column (10 × 250 mm, Waters, Sunfire TM, USA).

Plant Material. The whole plants of G. eriocarpum were collected from Yunnan Province, People’s Republic of China, in May 2012. Voucher specimens (KUN_0186703) were deposited at the State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences.

Extraction and Isolation. The whole plants of G. eriocarpum (1.5 kg) were extracted with MeOH (3 times, each time 3h) under reflux at 60 °C. The resulting MeOH extract (64.5 g) was applied to Diaion HP20SS column chromatography (CC), eluting with MeOH/H2O (0:1–1:0), to give five fractions (Fr. 1–5). Fr. 2 (7.6 g) was subjected to CC over Sephadex LH-20 (MeOH/H2O, 0:100, 30:70, 60:90, 100:0) and silica gel (CHCl3/MeOH/H2O, 8:2:0.2–6:4:1) to give compounds 9 (6 mg), 13 (5 mg), and 15 (10 mg). Fr. 4 (15 g) was applied to CC over Sephadex LH-20 (MeOH/H2O, 0:100, 30:70, 60:90, 100:0) and silica gel (CHCl3/MeOH/H2O, 8:2:0.2–6:4:1), and then the semi-preparative HPLC with a isocratic flow of H2O/MeCN (flowing rate: 3 ml/min, 82:18) to afford compounds 4 (5 mg), 5 (13 mg), and 7 (13 mg). The residue was chromato-graphed over MCIgel CHP-20P (MeOH/H2O, 5% to 100% with a 10% increment), then purified by semi-preparative HPLC (flowing rate: 5 mL/min, 82:18) to afford 1 (2 mg), 6 (22 mg), 8 (5 mg), 3 (3 mg). Fr. 5 (8.2 g) was subjected to CC over Sephadex LH-20 (MeOH/H2O, 0:100, 30:70, 60:90, 100:0) and silica gel (CHCl3/MeOH/H2O, 8:2:0.2–6:4:1), and then purified through the semi-preparative HPLC to afford compounds 2 (2 mg), 10 (3 mg), 11 (3 mg), 12 (5 mg), 14 (6 mg), 16 and 17 (3 mg).

2-β-D-Glucopyranosyloxy-4-methoxy-6-hydroxyisovalerophenone (1). Amorphous white powder, −14.1 (c 0.10, MeOH); UV (MeOH) λmax (log ε) 204 (4.15), 224 (4.17), 284 (4.20); IR (KBr) 𝒱max 3450, 2925, 1627, 1597, 1427, 1384, 1276, 1220, 1167, 1083 cm-1; HREIMS m/z 386.1572 [M]+ (calcd for C18H26O9, 386.1577); 1H NMR (CD3OD, 500 MHz) and 13C NMR (CD3OD, 125 MHz) are given in Table 1.

Cannabiside D (2). Amorphous white powder, −42.0 (c 0.10, MeOH); positive ESIMS m/z 425 [M+Na]+, C19H30O9; 1H NMR (CD3OD, 500 MHz) and 13C NMR (CD3OD, 125 MHz) are given in Table 1.

Glochidionionoside E (3). Amorphous white powder, −44.1 (c 0.10, MeOH); negative ESIMS m/z 437 [M+Cl]-, C19H30O9; 1H NMR (CD3OD, 600 MHz) and 13C NMR (CD3OD, 150 MHz) are given in Table 1.